Chevrolet - TRUCK - Workshop Manual - 1976 - 1976

I C H E V R O L E T 1976 CHEVROLET FOREWORD This manual has been prepared as a supplement to the 1974 Light Duty Truck Service and Overhaul Manuals. It covers, in separate sections, diagnosis, maintenance adjustments, service operations, and overhaul procedures for the 1976 10-30 Series truck models. Complete wiring diagrams for the vehicles covered in this manual will be found in the separate 1976 Truck Wiring Diagram booklet (ST-352-76). Any reference to brand names in this manual is intended merely as an example of the types of lubricants, tools, mate­ rials, etc., recommended for use. In all cases, an equivalent may be used. All information, illustrations and specifications contained in this literature are based on the latest product information avail­ able at the time of publication approval. The right is reserved to make changes at any time without notice. CHEVROLET M OTOR D IVISIO N General M otors Corporation DETROIT, MICHIGAN IMPORTANT SAFETY NOTICE P ro p e r serv ice a n d re p a ir is im p o r ta n t to th e safe, re lia b le o p e r a tio n o f all m o to r v eh ic le s. T h e service p ro c e d u re s re c o m m e n d e d a n d d e sc rib e d in th is service m a n u a l a re e ffe c tiv e m e th o d s , fo r p e rfo rm in g service o p e ra tio n s . S o m e o f th e s e serv ice o p e ra tio n s re q u ire th e u se o f to o ls sp e c ia lly d esig n e d f o r th e p u rp o s e . T h e sp ecial to o ls s h o u ld b e u se d w h e n a n d as re c o m m e n d e d . I t is im p o r ta n t t o n o te t h a t so m e w arn in g s a g a in st th e u se o f sp e cific service m e th o d s t h a t c a n d a m a g e th e v e h ic le o r re n d e r it u n sa fe a re s ta te d in th is service m a n u a l. I t is also im p o r ta n t to u n d e rs ta n d th e s e w arn in g s a re n o t e x h a u s tiv e . W e c o u ld n o t p o ssib ly k n o w , e v a lu a te a n d advise th e service tr a d e o f all c o n c e iv a b le w ay s in w h ic h service m ig h t b e d o n e o r o f th e p o ssib le h a z a rd o u s c o n s e q u e n c e s o f e a ch w ay . C o n s e q u e n tly , w e h av e n o t u n d e r ta k e n a n y s u c h b r o a d e v a lu a tio n . A c c o rd in g ly , a n y o n e w h o uses a service p ro c e d u r e o r to o l w h ic h is n o t re c o m m e n d e d b y th e m a n u fa c tu re r m u s t f irs t s a tis fy h im s e lf th o ro u g h ly t h a t n e ith e r h is s a fe ty n o r v e h icle s a fe ty w ill b e je o p a r d iz e d b y th e service m e th o d h e selec ts. SECTION INDEX NAME SECTION 1976 10-30 SERIES TRUCK CHASSIS SERVICE and OVERHAUL MANUAL SUPPLEMENT GENERAL INFORMATION AND LUBRICATION HEATER AND AIR CONDITIONING 1A 1B BODY FRAME FRONT SUSPENSION REAR SUSPENSION AND DRIVELINE BRAKES ENGINE FOREWORD This manual has been prepared as a supplement to the 1974 Light Duty Truck Service and Overhaul Manuals. It covers, in separate sections, diagnosis, maintenance adjustments, service operations, and overhaul procedures for the 1976 10-30 Series truck models. Complete wiring diagrams for the vehicles covered in this manual will be found in the separate 1976 Truck Wiring Diagram booklet (ST-352-76). Any reference to brand names in this manual is intended merely as an example of the types of lubricants, tools, mate­ rials, etc., recommended for use. In all cases, an equivalent may be used. All information, illustrations and specifications contained in this literature are based on the latest product information avail­ able at the time of publication approval. The right is reserved to make changes at any time without notice. 6K 6M 6T 6Y 7M 7A 8 ENGINE COOLING ENGINE FUEL EMISSION CONTROL SYSTEMS ENGINE ELECTRICAL CLUTCH AND MANUAL TRANSMISSION AUTOMATIC TRANSMISSION FUEL TANK AND EXHAUST SYSTEM STEERING SERVICE SECTION The Service Section of this manual includes new or revised procedures for maintenance and adjustments, minor service op­ erations and replacement of components. CHEVROLET M OTOR DIVISIO N General Motors Corporation DETROIT, MICHIGAN 10 11 12 13 14 15 WHEELS AND TIRES CHASSIS SHEET METAL ELECTRICAL— BODY AND CHASSIS RADIATOR — See Section 6K GRILLE — See Section 11 BUMPERS ACCESSORIES SPECIFICATIONS OF MANUAL © 1976 General M otors C orporation Printed in U.S.A. AT REAR S E C TIO N 0 GENERAL INFORMATION AND LUBRICATION C O N T E N T S OF T H IS S E C T IO N G eneral Inform ation........................................................................... L ubrication............................................................................................ 0-1 0-6 GENERAL INFORMATION IN D E X T ruck Model Identification.............................................. 0-1 Vehicle Identification Num ber and Rating P la te .......0-1 Engine N u m b er.................................................................. 0-1 Unit and Serial Number Locations................................0-1 Truck Model Identification All 10-30 series models are identified by this model system. Basically the designation consists of 7 characters, 2 letters followed by five numbers. The first letter indicates a Chevrolet model and the second identifies the chassis type. The first number designates the GVW range, the second and third identify the cab-to-axle dimension or model type and the last two identify the cab or body style. VEHICLE IDENTIFICATION NUMBER AND RATING PLATE A combination vehicle identification number and rating plate used on all models (fig. 1) is located on the left door pillar of CK models. On Forw ard Control models (except P30 M otor Home Chassis) it is attached to the dash and toe panel. The vehicle identification number stamped on the plate decodes into the information shown in Figure 2. Plate Information ENGINE NUMBER The engine num ber indicates manufacturing plant, month and day of manufacture, and transmission type. A typical engine number would be F1210TFA, which would breakdown thus: F - M anufacturing Plant (F-Flint, T-Tonawanda) 12 - M onth of M anufacture (December) 10 - Day of M anufacture (tenth) T - Truck Service Parts Identification Plate....................................0-3 Keys and L ocks................................................................. 0-3 Emergency S tartin g............................................................0-3 T ow ing.................................................................................. 0-4 FA - Transmission and engine type UNIT AND SERIAL NUMBER LOCATIONS For the convenience of service technicians and engineers when writing up certain business papers such as W arranty Reports, Product Inform ation Reports, or reporting product failures in any way, the location of the various unit numbers have been indicated. These unit numbers and their prefix or suffix are necessary on these papers for various reasons such as accounting, follow-up on production, etc. The prefixes on certain units identify the plant in which the unit was m anufactured and thereby permits proper follow-up of the plant involved to get corrections made when necessary. Always include the prefix in the number. Axles • Series 10, 20 and P30 Code is stamped on Front of Right Rear Axle Tube. • Series C, G30 (except dual wheel) code is stamped at the Forw ard Upper Surface of Carrier. • Dual Wheel P art Num ber and Production Code is stamped on Front of Right Axle Tube. Transmissions • 3-Speed Transmission U nit Number Located on Lower Left Side of Case Adjacent to Rear of Cover. • 4-Speed Transmission Unit Number Stamped on Rear of Case, Above Output. • Turbo Hydra-M atic 350 Transmission Unit Number Located on Right Rear Vertical Surface of Oil Pan. TRUC K SUPP - SER VIC E 0-2 GENERAL IN F O R M A T IO N A N D L U B R IC A T IO N TRUCK MODEL IDENTIFICATION c c 0703 + E63 + LF5 1. C = Chevrolet; T = GMC Truck 2. Chassis Type__________________ 3. GVW R ange__________________ 4. CA Dimension/Model Type 5. Cab or Body S ty le _______ 6 . Body Ordering C o de_____ 7. Engine Ordering Code___ © © CA Dimension/Model Type Chassis Type C— C o n ve n tio n a l 4 x 2 G— F orw ard C o n tro l 4 x 2 (B ody-F ram e In te g ra l) K— C o n v e n tio n a l 4 x 4 (Four W h e e l Drive) P— Forw ard C o n tro l 4 x 2 (C o n v e n tio n a l) © Series/GVW Range 1 — 4800 to 7300 2 — 6400 to 8400 3 — 6400 to 1 4,000 0 5 — B la z e r, Jimmy, S te p -V a n , V a lu e Van 07- 4 2 "/P ic k u p , C hassis-Cab 08- FC or M o to r Home Chassis, S te p -V a n , V a lu e Van 09- 5 6 'V S u b u rb a n , C hassis-C ab, Pickup lO — 60"/FC i Chassis, Chevy V a n , V a n d u ra , S p o rtva n , R ally W a g o n , C hassis-C ab, S te p -V a n , V a lu e Van 1 1— M o to r Home Chassis 1 3 — Chevy V a n , V a n d u ra , S p o rtva n , R a lly W a g o n , C u ta w a y V a n , H i-C u b e Van 14 — 84"/FC o r M o to r Home Chassis, C hassis-C ab, S te p -V a n , V a lu e Van 16— C u ta w a y V an, H i-C u b e Van 18— M o to r Home Chassis © Body Code © Cab or Body Style 0 3 — C o n v e n tio n a l C ab (C-K m odels) 0 4 — C u ta w a y V a n , H i-C u b e Van (G m odels) 0 5 — Chevy V a n , V a n d u ra 0 6 — S u b u rb a n /S p o rtv a n , R ally W a g o n w ith P anel Rear Doors 16— B la ze r, Jimmy 3 2 — M o to r Home Chassis 4 2 — F orw ard C o n tro l Chassis, S te p -V a n , V a lu e Van 4 3 — Bonus C ab 6 3 — C rew C ab Z W 9 — Base Body Z 5 8 — B la ze r, Jimmy w /W h ite Top Z 5 9 — B la ze r, Jimmy w /B la ck Top Z 6 4 — RV C u ta w a y Van E3 1 — H i-C u b e Van (1 O' Steel 9 6 " W id e ) E32— S te p -V a n , V a lu e Van (S teel) E33— S te p -V a n , V a lu e Van (A lum inum ) E 34— H i-C u b e Van (10' Steel 8 2 " W id e ) E 36— H i-C u b e Van (1 O' A lum inum ) E 38— H i-C u b e Van (12' Steel) E 39— H i-C u b e Van (1 2' A lum inum ) E 55— S u b u rb a n (w/End G a te ) E 62— S tepside (F enderside) Pickup E 63— Fleetside (W id e S ide) Pickup E94— B e a u v ille S portvan, R a lly STX Engine Code LD4— 250 Six L25 — 292 Six LF5 — 350-2 V8 LS9— 3 5 0 -4 V8 LF4 — 4 0 0 -4 V8 LF8 — 4 5 4 -4 V8 T R U C K SUP P - SER VIC E GENERAL IN F O R M A T I O N A N D L U B R IC A T IO N 0-3 Delcotrons n MFD. BY GENERAL MOTORS CORPORATION ^ GVWRI GAWR FRONT 1 1 I ^ Delcotron Unit Serial N um ber Located at Top of Rear Housing. ^ Batteries GAWR REAR V IN l Battery Code Num ber Located on Cell Cover Top of Battery. Starters I CAMPER LOADING DATA CWR]_____DIM A l 1 DIM B l 1 Starter Serial N um ber and Production Date Stamped on Outer Case, Toward Rear. INFLATION DATA FOR TIRES FURNISHED WITH VEHICLE FRONT I 1 PRESSURE □ REAR 1 1 PRESSURE j O Q WARRANTY VOIDED IF LOADED IN EXCESS OF RATINGS □ Q SEE OWNERS MANUAL FOR OTHER LOADING AND INFLATION DATA Fig. 1 ~ V e h ic le Id e n tific a tio n N u m b e r and R ating P late In fo rm a tio n ENGINE D ESIG NA TIO N D L T Q V Y U S D IV IS IO N = = = = = = = = L6-250-1 V 8-350-4 L6-292-1 V 8-305-2 V 8-350-2 V 8-3 50-4 V 8-4 00-4 V 8-4 54-4 V 8-454-4 IMPORTANT: RETAIN THIS PLATE AS A PERMANENT RECORD MODEL YEAR 6 = 1976 fo r a l Series. C = CHEVROLET T = GMT CHASSIS TYPE SEQUENTIAL NUMBER C = 2 WHEEL DRIVE G = LIG H T DUTY FORWARD CONTROL K = 4 WHEEL DRIVE L = LIGHT UTILITY P = FORW ARD CONTROL BO D Y STYLE 2-F orw a rd C ontrol chassis only 3-C ab-chassis (C utaw ay) 4 -C a b a n d p ic k u p box 5 -Van and Panel 6 -S u b u rb a n bo dy 7 -M o to r Home 8 -U tility (Blazer) ASSEMBLY A -L a k e w o o d B -B a ltim o re F-Flint J- J a n e s v ille PLANT V -G M T ru ck-P o n tia c S-St. Louis U -Lo rdsto w n Z -F re m o n t 1-O shav/a 3-G M A D D e tro it 4-S ca rboroug h Fig. 2 -V e h ic le Id e n tific a tio n N u m b e r • The Turbo Hydra-M atic Transmission 400 Serial N um ber is Located on the Light Blue Plate on the Right Side of the Transmission. Engines • 6-Cylinder Engine U nit N um ber Located on Pad at Fig. 3 -S e r v ic e P arts Id e n tific a tio n Plate SERVICE PARTS IDENTIFICATION PLATE The Service Parts Identification Plate (fig. 3) is provided on all Truck models. On most series it will be located on the inside of the glove box door, or, on Forw ard Control series, it will be located on an inner body panel. The plate lists the vehicle serial number, wheelbase, and all Production options or Special Equipment on the vehicle when it was shipped from the factory including paint information. A LW A YS REFER TO THIS IN FO R M A TIO N W HEN ORDERING PARTS. KEYS AND LOCKS Two keys are provided with each vehicle. Different lock cylinders operated by a separate key are available as an option for the sliding side load door and rear load doors. EMERGENCY STARTING • Engines in vehicles with autom atic transmissions cannot be started by pushing or towing the vehicle. • Never tow or push trucks equipped with light duty emission control systems to start engine. • A vehicle with a discharged battery may be started by transferring electrical power from a battery in another car - called "jump starting". Right H and Side of Cylinder Block at Rear of Jump Starting Distributor. Jump starting may be dangerous and should be attempted only, if the following three conditions are met. If they are not, we strongly recommend that you leave the starting to a competent mechanic. • 8-Cylinder Engine U nit N um ber Located on Pad at Front, Right H and Side of Cylinder Block. TR U C K SUPP - S E R VIC E 0-4 GENERAL IN F O R M A T IO N A N D L U B R IC A T IO N • The battery in the OTHER vehicle must be 12 volt and negatively grounded, like the one in THIS vehicle. (Check the other vehicle’s owner’s manual to see if it is.) • The battery in THIS vehicle must be equipped with flame arrestor vents (like the original equipment Delco "Freedom" battery) or flame arrestor type filler/vent caps. • If the battery is a Delco sealed-type battery without filler opening or caps, its charge indicator must be dark, with or without green dot showing. Do NOT attem pt jum p starting if the charge indicator has a light or bright center. CAUTION: Departures from these conditions or the procedure below could result in: (1) serious personal injury (particularly to eyes) or property damage from such causes as battery explosion, battery acid, or electrical burns; and/or (2) damage to electronic components o f either vehicle. Never expose battery to open flame or electric spark-batteries generate a gas which is flammable and explosive. Do not allow battery fluid to contact eyes, skin, fabrics, or painted surfaces-fluid is a corrosive acid. Flush any contacted area with water immediately and thoroughly. Be careful that metal tools, or jum per cables do not contact the positive battery terminal (or metal in contact with it) and any other metal on the vehicle, because a short circuit could occur. Batteries should always be kept out of the reach of children. Jump Start Procedure 1. W ear eye protection and remove rings, metal watch bands, and other metal jewelry. 2. Set parking brake firmly. Place automatic transmission in PARK in both vehicles (don’t let vehicles touch); and turn ignition key to LOCK in vehicle with discharged battery (N eutral and OFF in vehicles with manual transmission). Also turn off lights, heater, and all unnecessary electrical loads. 3. A ttach one end of a jum per cable to one battery’s positive terminal (identified by a red color " + ", or "P" on the battery case, post, or clamp), and the other end of the same cable to the positive terminal of the other battery. 4. A ttach the remaining jum per cable FIRST to the negative term inal (black color, or "N ") of the OTHER vehicle’s battery, (regardless of which vehicle has the discharged battery) and N to the negative term inal of the battery in THIS vehicle - thus taking advantage of the flame arrestor feature on the battery in THIS vehicle, should a spark occur. 5. Start engine in the vehicle that is providing the jum p start (if it was not running). Let run a few minutes, then start the engine in the vehicle that has the discharged battery. 6. Reverse the above sequence EXACTLY when removing the jum per cables; taking care to remove the cable from the negative terminal of the battery in THIS vehicle as the FIRST step. PUSH STARTING - TRUCKS W ITH HEAVY DUTY EMISSION CONTROL SYSTEMS CAUTION: Trucks equipped with light duty emission control systems must not be pushed or towed to start. If your truck is equipped with a manual 3-speed or 4-speed transmission, it can be started in an emergency by pushing. When being pushed to start the engine, turn off all unnecessary electrical loads, turn ignition to "O N", depress the clutch pedal and place the shift lever in high gear. Release the clutch pedal when speed reaches 10 to 15 miles per hour. Bumpers and other parts contacted by the pushing vehicle should be protected from damage during pushing. Never tow the truck to start. TOW ING All Except Four Wheel Drive Trucks Normally your vehicle may be towed with all four wheels on the ground for distances up to 50 miles at speeds of less than 35 M PH. The engine should be off and the transmission in neutral. However, the rear wheels must be raised off the ground or the drive shaft disconnected when the transmission is not operating properly or when a speed of 35 M PH or distance of 50 miles will be exceeded. CAUTION: I f a truck is towed on its front wheels only, the steering wheel must be secured with the wheels in a straight ahead position. Four Wheel Drive Trucks It is recommended that the truck be towed with the front wheels off the ground. The truck can be towed, however, with the rear wheels off the ground if there is damage in the rear wheel area. In this event, the transmission selector lever should be placed in the "N " (neutral) position and with conventional four wheel drive the front drive disengaged. With Full Time four wheel drive the transfer case should be in high. Towing speeds should not exceed 35 M PH for distances up to 50 miles. If truck is towed on its front wheels, the steering wheel should be secured to keep the front wheels in a straight-ahead position. When towing the vehicle at slow speeds (approx. 20 M PH), for a very short distance only, the transmission must be in N EU TR A L and with conventional four wheel drive the transfer case MUST be in "TW O W H EEL H IG H ". W ith Full Time four wheel drive the transfer case should be in high. When towing the vehicle at faster speeds for greater distances, the following steps M UST be taken: • If front wheels are on the road, disconnect the front drive shaft. T R U C K SUP P - SER VIC E GENERAL IN F O R M A T I O N A N D L U B R IC A T IO N • If rear wheels are on the road, disconnect the rear drive shaft. STEEL TUBING REPLACEMENT In the event that replacement of steel tubing is required on brake line, fuel line, evaporative emission, and transmission cooling lines, only the recommended steel replacement tubing should be used. Only special steel tubing should be used to replace brake line. T hat is, a double wrapped and brazed steel tubing meeting G.M . Specification 123 M. Further, any other steel tubing should be replaced only with the released steel tubing or its equivalent. U nder no condition should copper or aluminum tubing be used to replace steel tubing. Those m aterials do not have satisfactory fatigue durability to withstand normal vehicle vibrations. All steel tubing should be flared using the upset (double lap) flare m ethod which is detailed in Section 5 of this Manual. VEHICLE LOADING 0-5 LOADED— MAXIMUM GVWR: 6200-LBS. FRONT GAW R: 3250 LBS. ^Front C u rb 2261 lbs. *R e a r C u rb 1549 lbs. R ear C a rg o & Front C a rg o & Pass. Load REAR GAW R: 3582 LBS. 450 lbs. Pass. Load 1940 lb s . 3 4 8 9 lbs. 2711 lbs. TOTAL W EIG HT AT G R O U N D: 6200 lbs. Vehicle loading must be controlled so weights do not exceed the numbers shown on the Vehicle Identification Num ber and Rating Plate for the vehicle. * C u rb w e ig h t e q u a ls th e w e ig h t o f the v e h ic le w ith o u t d riv e r, A typical example of a truck in a loaded condition is shown in Figure 4. N ote that the axle or GVW capabilities are not exceeded. Fig. 4 - T y p ic a l V e h ic le L o ad ed C o n d itio n p a sse n g e r o r c a rg o , b u t in c lu d in g fu e l a n d c o o la n t. TR U C K SUPP - S ER VIC E 0-6 GENERAL IN F O R M A T IO N A N D LU B R IC A T IO N LUBRICATION IN D E X M aintenance Schedule.......................................................0-6 E ngine................................................................................... 0-6 Oil and Filter Recom m endations................................ 0-6 Drive B elts........................................................................0-7 Positive Crankcase Ventilation (P.C.V.)..................... 0-7 Air Injection R eactor System (A .I.R .)...................... 0-8 Controlled Combustion System (C.C.S.).................... 0-8 Evaporation C ontrol System (E.C.S.)..........................0-8 Early Fuel Evaporation (E.F.E.) System...................0-8 A ir Cleaner........................................................................0-8 Fuel F ilte r......................................................................... 0-8 G overnor............................................................................ 0-8 Accelerator L inkage........................................................ 0-8 Automatic Transmission Fluid Recommendations.... 0-8 M anual T ransm ission....................................................... 0-9 Transmission Shift L in k ag e.............................................0-9 C lu tc h ................................................................................... 0-9 Rear Axle S tandard............................................................................. 0-9 Propeller Shaft Slip Joints................................................ 0-9 Universal Jo in ts.................................................................. 0-9 Wheel Bearings F ro n t................................................................................... 0-9 R ear..................................................................................... 0-9 Brake M aster C ylinder.....................................................0-10 Brake and Clutch Pedal Springs....................................0-10 Parking Brake......................................................................0-10 Steering Manual Steering G e a r.....................................................0-10 Steering Linkage and Suspension................................ 0-10 Hood Latch and Hood H inge........................................ 0-10 Body Lubrication...............................................................0-10 Speedometer A d a p ter........................................................ 0-11 Complete M aintenance Schedule....................................0-12 Lubrication Diagrams Conventional M odels.......................................................0-19 1/2 Ton G Models.......................................................... 0-20 M A IN T E N A N C E SC HED U LE A separate maintenance folder has been provided with each vehicle which contains a complete schedule and brief explanation of the safety, emission control, lubrication and general maintenance it requires. The maintenance folder information is supplemented by this section of this manual, as well as the separate vehicle and emissions warranty booklet also furnished with each vehicle. Read all three publications for a full understanding of vehicle maintenance requirements. The time or mileage intervals for lubrication and maintenance services outlined in this section are intended as a general guide for establishing regular maintenance and lubrication periods for trucks with light duty emission control systems (see chart). Sustained heavy duty and high speed operation or operation under adverse conditions may require more frequent servicing. For maintenance and lubrication information on trucks designated with heavy duty emission control systems, continue to refer to Section 0 of the 1974 Light Duty Truck Shop Manual. LIGHT AND HEAVY DUTY EMISSION CLASS VEHICLES Light Duty Vehicle C l 0-Pickup (up to 6000 lbs. GVW) G-10 Van H e a v y D uty C l 0-Pickup (over 6000 lbs. GVW) C 10-Suburban C -10-Blazer, Jimmy C20-30 A ll models G-20, 30 Van A ll K models A ll P models ENGINE regardless of model year and previous engine oil quality recommendations. Oil and Filter Recommendations Oil Change Period The letter designation "SE" has been established to correspond with the requirements of GM 6136-M. "SE" engine oils will be better quality and perform better than those identified with "SA" through "SD" designations and are recommended for all light-duty gasoline trucks • Use only SE engine oil. • Change oil each 6 months or 7,500 miles. If more than 7,500 miles are driven in a 6 month period, change oil each 7,500 miles. T R U C K SUP P - S ER VICE GENERAL IN F O R M A T I O N A N D L U B R IC A T IO N • Change oil each 3 m onths or 3,000 miles, whichever occurs first, under the following conditions: -D riving in dusty conditions. -T railer pulling or cam per use. To help assure good cold and hot s ta rtin g , as w e ll as maximum e n g in e life , fu e l economy, and o il economy, select the p ro p e r viscosity from the te m p e ra tu re ra n g e a n tic ip a te d from the fo llo w in g chart: -F requent long runs at high speeds and high ambient temperatures. RECOMMENDED SAE VISCOSITY GRADES 1 1 -M o to r Home use. • Replace the oil filter at the first oil change, and every second oil change thereafter. AC oil filters (or equivalent) provide excellent engine protection. The above recommendations apply to the first change as well as subsequent oil changes. The oil change interval for the engine is based on the use of SE oils and quality oil filters. Oil change intervals longer than those listed above will seriously reduce engine life and may affect the m anufacturer’s obligation under the provisions of the New Vehicle W arranty. A high quality SE oil was installed in the engine at the factory. It is not necessary to change this factory-installed oil prior to the recommended norm al change period. However, check the oil level more frequently during the break-in period since higher oil consum ption is normal until the piston rings become seated. NOTE: Non-detergent and other low quality oils are specifically not recommended. Oil Filter Type and Capacity • Throwaway type, 1 quart U.S. measure, .75 quart Imperial measure. • 250 cu. in., 292 cu. in., AC Type PF-25. 350 cu. in. 454 cu. in., AC Type PF-35. Crankcase Capacity (Does Not Include Filter) • 292 L6 Engine; 5 quarts U.S. measure, 4.25 quarts Imperial measure. • All other engines; 4 quarts U.S. measure, 3.25 quarts Im perial measure. Recommended Viscosity Select the proper oil viscosity from the following chart: The proper oil viscosity helps assure good cold and hot starting. 1 1 1 1 J 1 10W JO, 1 0 W 40 2 0 W 4 0 W 11 2 0 W 50 V 10W, 5W-30, 10W-30, 10W 40 -Extensive idling. • Operation in dust storms may require an immediate oil change. 2 0 W 20 1 -S top and go type service such as delivery trucks, etc. -S hort-trip operation at freezing tem peratures (engine not thoroughly warmed-up). 0-7 11 h m i n u n M °F - 2 0 l„ » r C — 30 1 ii m m 1 1 0 20 ' -2 0 40 ...... T ..........T ' -1 0 60 16 80 i 0 ‘ t 30 10 20 TEMPERATURE RANGE ANTICIPATED BEFORE NEXT OIL CHANGE 40 NOTE: SAE 5W -30 oils are recommended for all seasons in vehicles normally operated in Canada. SAE 5W -20 oils are not recommended for sustained high-speed driving. SAE 30 oils may be used at temperatures above 40°F (4°C). "FULL" and "A D D O IL". If the oil is at or below the "ADD" m ark on the dipstick, oil should be added as necessary. The oil level should be maintained in the safety margin, neither going above the "FU LL" line nor below "A D D OIL" line. NOTE: The oil gauge rod is also marked "Use SE Engine Oil" as a rem inder to use only SE oils. Supplemental Engine Oil Additives The regular use of supplemental additives is specifically not recommended and will increase operating costs. However, supplemental additives are available that can effectively and economically solve certain specific problems without causing other difficulties. For example, if higher detergency is required to reduce varnish and sludge deposits resulting from some unusual operational difficulty, a thoroughly tested and approved additive - "G.M. Super Engine Oil Supplement" (or equivalent) - is available. Drive Belts Drive belts should be checked every 7,500 miles or 6 months for proper tension. A loose belt will affect water pump and generator operation. POSITIVE CRANKCASE VENTILATION (P.C.V.) Checking Oil Level VALVE The engine oil should be m aintained at proper level. The best time to check it is before operating the engine or as the last step in a fuel stop. This will allow the oil accumulation in the engine to drain back in the crankcase. To check the level, remove the oil gauge rod (dipstick), wipe it clean and reinsert it firmly for an accurate reading. The oil gauge rod is marked Every 30,000 miles or 24 months the valve should be replaced. Connecting hoses, fittings and flame arrestor should be cleaned. A t every oil change the system should be tested for proper function and serviced, if necessary. (Also see maintenance schedule at end of this section.) TRUC K S UPP - S E R VIC E 0-8 GENERAL IN F O R M A T IO N A N D L U B R IC A T IO N AIR INJECTION REACTOR SYSTEM A U TO M ATIC TRANSM ISSIO N (A.I.R.)--CONTROLLED COMBUSTION FLUID RECOM M ENDATION SYSTEM (C.C.S.) Use autom atic transmission fluids identified with the mark The Air Injection Reactor system should have the drive belt inspected for wear and tension every 24 m onths or 30,000 miles, whichever occurs first. In addition, complete effectiveness of either system, as well as full power and performance, depends upon idle speed, ignition timing, and idle fuel m ixture being set according to specification. A quality tune-up which includes these adjustments should be performed periodically to assure normal engine efficiency, operation and performance. EVAPORATION CONTROL SYSTEM (E.C.S.) Every 24 m onths or 30,000 miles (more often under dusty conditions) the filter in the base of the canister must be replaced and the canister inspected. EARLY FUEL EVAPORATION (E.F.E.) SYSTEM First 7,500 miles or 6 m onths check valve for freedom of operation. A binding condition must be corrected. Check hoses for cracking, abrasion or deterioration. Replace parts as necessary. AIR CLEANER CAUTION: Do not remove the engine air cleaner unless temporary removal is necessary during repair or maintenance o f the vehicle. When the air cleaner is removed backfiring can cause fire in the engine compartment. NOTE: U nder prolonged dusty driving conditions, it is recommended that these operations be performed more often. Replace the engine air cleaner element under normal operating conditions every 30,000 miles. Crankcase Ventilation Filter (Located W ithin Air Cleaner) If so equipped, inspect every oil change and replace if necessary. Replace at least every 30,000 miles; more often under dusty driving conditions. FUEL FILTER DEXRO N® II. Check the fluid level at each engine oil change period. Automatic transmissions are frequently overfilled because the fluid level is checked when the fluid is cold and the dipstick indicates fluid should be added. However, the low reading is normal since the level will rise as the fluid tem perature increases. A level change of over 3 /4 inch w ill occur as fluid temperature rises from 60°F to 180°F. Overfilling can cause foaming and loss of fluid through the vent. Slippage and transmission failure can result. Fluid level too low can cause slipping, particularly, when the transmission is cold or the car is on a hill. Check the transmission fluid level w ith engine running, the shift lever in PARK and the car level. NOTE: If the vehicle has recently been operated for an extended period at high speed or in city traffic in hot weather or the vehicle is being used to pull a trailer, an accurate fluid level cannot be determined until the fluid has cooled down - usually about 30 minutes after the vehicle has been parked. Remove the dipstick and touch the transmission end of the dipstick cautiously to find out if the fluid is cool, warm or hot. Wipe it clean and re-insert until cap seats. Remove dipstick and note readings. • If the fluid feels cool, about room tem perature 65°F to 85°F the level should be 1/8 to 3/8 inch below the ADD mark. The dipstick has two dimples below the "ADD" mark to show this range. • If it feels warm the level should be close to the ADD mark (either above or below). • If it feels hot (cannot be held comfortably) the level should be between the ADD and FULL marks. Replace filter element located in carburetor inlet every 12 months or 15,000 miles whichever occurs first, or, if an in-line filter is also used, every 30,000 miles. Replace in-line filter every 30,000 miles. GOVERNOR (6 5 ° -8 5 °F .) (1 8 ° -2 9 ° C .) The attaching bolts should be kept tight, the optionally available governor should be kept clean externally and the filter element should be replaced every 15,000 miles. COOL HOT ACCELERATOR LINKAGE Lubricate with engine oil every 30,000 miles as follows: 1. On V8 engine, lubricate the ball stud at the carburetor lever. W ARM NOTE: DO NOT OVERFILL. It takes only one pint to raise level from ADD to FULL with a hot transmission. 2. On L6 engine, lubricate the two ball studs at the carburetor lever and lubricate the lever mounting stud. Do not lubricate the accelerator cable. T R U C K S UPP ■ SER VIC E GENERAL IN F O R M A T I O N A N D L U B R IC A T IO N water resistant EP chassis lubricant which meets General M otors Specification GM 6031-M. AUTO M ATIC TRAN SM ISSIO N DRAIN INTERVALS The transmission operating tem perature resulting from the type of driving conditions under which your vehicle is used is the main consideration in establishing the proper frequency of transmission fluid changes. Change the transmission fluid and filter every 15,000 miles if the vehicle is usually driven under one or more of the following conditions which are considered severe transmission service: • Where the outside tem perature regularly reaches 90°F. • In very hilly or m ountainous areas. • Frequent trailer pulling. • Commercial uses, such as taxi, police car or delivery service. If you do not use your vehicle under any of these conditions, change the fluid and filter every 60,000 miles. Change Turbo Hydra-Matic 400 and Turbo Hydra-Matic 3 5 0 fluid, remove fluid from the transmission sump, add approximately 7.5 pints U.S. measure (6.25 pints Im perial measure) for the T urbo H ydra-M atic 400 and 2 1/2 qts. U.S. measure (2 qts. Imperial measure) for the Turbo H ydra-M atic 350 of fresh fluid, to return level to proper m ark on the dipstick. -th e Turbo H ydra-M atic transmission sump filter should be replaced. Every 6 0,0 00 REAR AXLES Standard Every 6 m onths or 7,500 miles, whichever occurs first, check lubricant level and add lubricant, if necessary, to fill to level of filler plug hole. Use SAE 80W or SAE 80W-90 GL-5 G ear Lubricant. For those vehicles normally operated in Canada, use SAE 80W GL-5 G ear Lubricant. Positive Locking or Positraction • In heavy city traffic. To 0-9 Miles 400 Every 6 m onths or 7,500 miles, whichever occurs first, check lubricant level and add lubricant, if necessary, to fill to level of filler plug hole. Drain and refill at first 15,000 miles then maintain same as standard axle but, use only the special positraction differential lubricant. PROPELLER SHAFT SLIP JOINTS Propeller shaft slip joints should be lubricated every 7,500 miles or 6 m onths with water resistant EP chassis lubricant which meets General M otors Specification GM 6031-M. UNIVERSAL JOINTS All universal joints are the needle bearing type. Lubricate those universal joints (depending on truck model) equipped with lube fittings every 7,500 miles or 6 months with water resistant EP chassis lubricant which meets General M otors Specification GM 6031-M. M ore frequent lubes may be required on heavy duty or "Off the Road" operations. 3-AND 4-SPEED M AN UAL TRANM ISSIO N WHEEL BEARINGS LUBRICANT Front Every 6 m onths or 7,500 miles, whichever occurs first, check lubricant level and add lubricant, if necessary, to fill to level of filler plug hole with SAE 80W.or SAE 80W-90 GL-5 G ear Lubricant. If tem peratures below +32°F are expected, use SAE 80W GL-5 G ear Lubricant only. For those vehicles normally operated in Canada, use SAE 80W GL-5 G ear Lubricant only. TRANSM ISSIO N SHIFT LINKAGE (M ANUAL AND AUTOM ATIC) Every 7,500 miles or 6 m onths-lubricate shift linkage and, on M anual transmission floor control, lever contacting faces with water resistant EP chassis lubricant which meets General M otors Specification GM6031-M. NOTE: Use wheel bearing lubricant GM P art No. 1051344 or equivalent. This is a premium high melting point lubricant which meets all requirements of General M otors Specification GM 6031-M. Due to the weight of the tire and wheel assembly it is recommended that they be removed from hub before lubricating bearings to prevent damage to oil seal. Then remove the front wheel hub to lubricate the bearings. The bearings should be thoroughly cleaned before repacking with lubricant. Front wheels are equipped with tapered roller bearings on all trucks. Wheel bearings should be lubricated every 30,000 miles (12,000 miles in four wheel drive trucks). Do not mix wheel bearing lubricants. Clutch CAUTION: "Long fibre" type greases should not be The clutch pedal free travel should be checked at regular intervals. used on roller bearing front wheels. Rear Lubricate the clutch cross-shaft at fitting (on Series 10 Forw ard Control models also lubricate the clutch linkage idler lever at fitting) every 7,500 miles or 6 months with The rear wheel bearings receive their lubrication from the rear axle. W hen installing bearings which have been cleaned, prelube with wheel bearing grease. T R U C K SUP P - S E R VIC E 0 -1 0 GENERAL IN F O R M A T IO N A N D L U B R IC A T IO N BRAKE MASTER CYLINDER Check master cylinder fluid level in both reservoirs every 7,500 miles or 6 months. If the fluid is low in the reservoir, it should be filled to a point about 1/4" from the top rear of each reservoir with Delco Supreme No. 11 Hydraulic Brake Fluid or equivalent. BRAKE AND CLUTCH PEDAL SPRINGS Lubricate brake and clutch pedal springs every 7,500 miles or 6 months with engine oil for all models. PARKING BRAKE Every 7,500 miles or 6 months clean and lubricate all parking brake pivot points with water resistant EP chassis lubricant which meets General M otors Specification GM 6031-M. STEERING Manual Steering Gear The steering gear is factory-filled with steering gear lubricant. Seasonal change of this lubricant should not be performed and the housing should not be drained-no lubrication is required for the life of the steering gear. Every 30,000 miles, the gear should be inspected for seal leakage (actual solid grease-not just oily film). If a seal is replaced or the gear is overhauled, the gear housing should be refilled with No. 1051052 (13 oz. container) Steering Gear Lubricant which meets G M Specification GM4673-M or its equivalent. NOTE: Do not use EP Chassis Lube, which meets GM Specification GM 6031-M, to lubricate the gear. DO N OT O V ER -FILL the gear housing. Power Steering System Check the fluid level in the pump reservoir at each oil change period. A dd GM Power Steering Fluid (or D E X R O N ® II autom atic Transmission Fluid) or equivalent as necessary to bring level into proper range on filler cap indicator depending upon fluid temperature. If at operating tem perature (approximately 150°F-hot to the touch), fluid should be between "HOT" and "COLD" marks. If at room tem perature (approximately 70°F), fluid should be between "A D D " and "CO LD " marks. Fluid does not require periodic changing. STEERING LINKAGE AND SUSPENSION M aintain correct front end alignment to provide easy steering, longer tire life, and driving stability. Check control arm bushings and ball joints for wear. Lubricate tie rods, upper and lower control arms, and ball joints at fittings with water resistant EP chassis lubricant which meets General M otors Specification GM 6031-M every 7,500 miles or 6 months. Lubricate every 3,000 miles or 3 m onths whichever occurs first under the following conditions: • Driving in dusty or muddy conditions. • Extensive off-road use. NOTE: Ball joints must be at + 10°F. or more before lubricating. Keep spring to axle U bolts and shackle bolts properly tightened (see Specifications Section for torque recommendations). Check U bolt nuts after the first 1,000 miles of operation if the U bolt or U bolt nuts are changed in service. HOOD LATCH AND HOOD HINGE Every 7,500 miles or 6 months, whichever occurs first, lubricate hood latch assembly and hood hinge assembly as follows: 1. Wipe off any accumulation of dirt or contaimination on latch parts. 2. Apply lubriplate or equivalent to latch pilot bolt and latch locking plate. 3. Apply light engine oil to all pivot points in release mechanism, as well as prim ary and secondary latch mechanisms. 4. Lubricate hood hinges. 5. Make hood hinge and latch m echanism functional check to assure the assembly is working correctly. BODY LUBRICATION Norm al use of a truck causes metal-to-metal movement at certain points in the cab or body. Noise, wear and improper operation at these points will result when a protective film of lubricant is not provided. For exposed surfaces, such as door checks, door lock bolts, lock striker plates, dovetail bum per wedges, etc. apply a thin film of light engine oil. Where oil holes are provided in body parts a dripless oil can be safely used, but any lubricant should be used sparingly, and after application all excess should be carefully wiped off. T R U C K SUP P - SER VICE GENERAL IN F O R M A T I O N A N D L U B R IC A T IO N The seat adjusters and seat track, ordinarily overlooked, should be lubricated with water resistant EP chassis lubricant which meets General M otors Specification GM 6031-M. There are other points on bodies which may occasionally require lubrication and which are difficult to service, window regulators and controls are confined in the space between the upholstery and the outside door panel. Easy access to the working parts may be made by removing the trim. D oor weatherstrips and rubber hood bumpers should be lightly coated with a rubber lubricant. 0-11 brake or pan, exhaust system, brackets, parking brake cables. These corrosive effects, however, can be reduced by periodic flushing of the underbody with plain water. In geographic areas having a heavy concentration of such corrosive materials, it is recommended that the complete underbody be inspected and flushed at least once a year, preferably after a w inter’s exposure. Particular attention should be given to cleaning out underbody members where dirt and other foreign materials may have collected. UNDERBODY M AINTENANCE SPEEDOMETER ADAPTER The effects of salt and other corrosive m aterials used for ice and snow removal and dust control can result in accelerated rusting and deterioration of underbody components such as On vehicles so equipped, lubricate adapter at fitting with water resistant EP chassis grease which meets General M otors Specification GM 6031-M every 7,500 miles. T R U C K S UPP • S ER VIC E 0-12 GENERAL IN F O R M A T IO N A N D LUB R IC A T IO N COMPLETE VEHICLE MAINTENANCE SCHEDULE W hen To Perform Services (Months or Miles, Whichever Occurs First) Item No. Every 6 Months or 7,500 Miles 1 2 3 4 5 6 7 8 At 1st Oil Chg. - Then Every 2nd See Explanation Every 12 Months Every 12 M onths or 15,000 Miles Every 30,000 Miles Every 6 Months or 7,500 Miles Every 12 Months or 15,000 Miles At First 6 Months or 7,500 Miles - Then at 18 Month/ 22,500 M ile Intervals Every 12 Months or 15,000 Miles Every 18 Months or 22,500 Miles Every 22,500 Miles Every 24 M onths or 30,000 Miles Every 30,000 Miles 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 Services (For Details, See Numbered Paragraphs) ‘ Chassis Lubrication •*F luid Levels Check ‘ Engine Oil Change *Oil Filter Change Tire Rotation (Steel Belted Radial) Rear Axle Lube Change A ir Conditioning Check *Cooling System Check — Coolant Change & Hose Replacement Wheel Bearing Repack *Auto. Trans. Fluid & Filter Change Manual Steering Gear Check Clutch Cross Shaft Lubrication Owner Safety Checks Tire and Wheel Inspection *Exhaust System Check *Drive Belt Check *— Belt Replacement Suspension and Steering Check Brake and Power Steering Check Drum Brake and Parking Brake Check Throttle Linkage Check Underbody Flush & Check Bumper Check Thermo. Controlled A ir Cleaner Check Carburetor Choke Check Engine Idle Speed Adjustm ent EFE Valve Check Carburetor M ounting Torque Fuel Filter Replacement Vacuum Advance System & Hoses Check PCV System Check — PCV Valve & Filter Replacement Idle Stop Solenoid Check Spark Plug Wires Check Spark Plug Replacement Engine Tim ing A djustm ent & Dist. Check ECS System Check & Filter Replacement Fuel Cap, Tank and Lines Check A ir Cleaner Element Replacement • Also A Safety Service * Also An Emission Control Service TRUC K S U P P - SER VIC E GENERAL IN F O R M A T IO N A N D L U B R IC A T IO N E X P L A N A T IO N OF C O M P LE T E V E H IC LE M A IN T E N A N C E SC H ED U LE FOR SERIES 10, L-6 A N D V -8 EN G IN ES A N D L IG H T D U T Y E M IS S IO N S Y S T E M Presented below is a brief explanation of each of the Vehicle M aintenance services. N ORM AL VEHICLE USE -T h e maintenance instructions contained in this maintenance schedule are based on the assumption that vehicle will be used as designed: • To carry passengers and cargo within the limitations indicated on the vehicle tire placard affixed to either the edge of driver’s door or the inside of the glove box door. • On reasonable road surfaces within legal operating limits. • On a daily basis, as a general rule, for at least several miles. • On unleaded fuel. Unusual operating conditions will require more frequent vehicle maintenance as specified in the respective sections included below. Refer to the appropriate section of this manual for additional details on specific services. A listing of recommended lubricants and fluids is included at the end of this listing. S E C T IO N A LUBE A N D G E N E R A L M A IN T E N A N C E CHASSIS -L u b ricate all grease fittings in front suspension steering linkage and constant velocity universal joint. Also lubricate transmission shift linkage, hood latch, hood hinges, and parking brake cable guides and linkage, clutch linkage, propellor shaft slip joint, universal joints and brake and clutch pedal springs. Lubricate suspension and steering linkage every 3 m onths or 3,000 miles when operating under dusty or m uddy conditions and in extensive off-road use. A-1 0-1 3 A-3 ENGINE OIL **-C hange each 6 m onths or 7,500 miles, whichever occurs first under normal driving conditions, or each 3 m onths or 3,000 miles when the vehicle is operated under the following conditions: (a) driving in dusty conditions, (b) trailer pulling, (c) extensive idling or (d) short-trip operation at freezing tem peratures (with engine not thoroughly warmed-up). See elsewhere in this Section for additional details on engine oil. -R eplace at the first oil change and every other oil change thereafter. A-5 TIRES - T o equalize wear, rotate tires as illustrated in Section 10 of this M anual and adjust tire pressures. A-6 REAR AXLE -C h an g e lubricant at first 15,000 miles on Positraction axles. Change lubricant every 7,500 miles on all type rear axles or final drives when using vehicle to pull a trailer. A-7 AIR C O N D ITIO N IN G -C h e ck condition of air conditioning system hoses and refrigerant charge at sight glass (if so equipped). Replace hoses a n d /o r refrigerant if need is indicated. A-8 COOLING SYSTEM •*- A t 12 m onth or 15,000 mile intervals, wash radiator cap and filler neck with clean water, pressure test system and radiator cap for proper pressure holding capacity, tighten hose clamps and inspect condition of all cooling and heater hoses. Replace hoses if checked, swollen or otherwise deteriorated. Also each 12 m onths or 15,000 miles, clean exterior of radiator core and air conditioning condenser. Every 24 m onths or 30,000 miles, drain, flush, and refill the cooling system with a new coolant solution. A-9 WHEEL BEARINGS -C lean and repack front wheel bearings with a lubricant as specified in the "Recommended Fluids & Lubricants" chart at the end of this section. A-10 M A N U A L STEERING GEAR -C h eck for seal leakage around the pitman shaft and housing. If leakage is evident (solid grease oozing out-not just oily film), it should be corrected immediately. A -1 1 CLUTCH CROSS SHAFT -L u bricate clutch cross A-2 FLUID LEVELS -C h e c k level of fluid in brake master shaft lever. cylinder*, power steering pump*, battery, engine**, axle, transmission ** and windshield washer*. Engine coolant should be checked for proper level and freeze protection to at least -20°c (-29°F) or to the lowest tem perature expected during the period of vehicle operation.* Proper engine coolant also provides corrosion protection. A -12 A U TO M A TIC TR AN SM ISSIO N FLUID * *-U nder normal driving conditions, change the transmission fluid and service the sump filter (if so equipped) every 60,000 miles. Any significant fluid loss in any of these systems or units could mean that a malfunction is developing and corrective action should be taken immediately. On some models, a low fluid level in the brake m aster cylinder front reservoir could also be an indicator that the disc brake pads need replacing. U nder unusual conditions such as constant driving in heavy city traffic, trailer pulling, and commercial applications, services should be performed at 15,000 mile intervals. See elsewhere in this m anual for further details on transmission care. * Also a Safety Service ** Also an Emission Control Service TRUC K SUP P - S E R V IC E 0 -1 4 GENERAL IN F O R M A T IO N A N D L U B R IC A T IO N S E C TIO N B -S A F E T Y M A IN T E N A N C E NOTE: Items B-l (a) thru (w) can be checked by the owner, while Items B-2 thru B-10 should only be checked by a qualified mechanic. It is particularly im portant that any safety systems which may have been adversely affected in an accident be checked and repaired as necessary before the vehicle is returned to use. B-1 SAFETY CHECKS TO BE PERFORMED BY OWNER -T h e following checks should be made regularly during operation at no greater interval than 6 m onths or 7,500 miles, whichever occurs first, and more often when the need is indicated. Any deficiencies should be brought to the attention of your dealer or another service outlet, as soon as possible, so the advice of a qualified mechanic is available regarding the need for repairs or replacements. a. STEERING COLUMN LOCK -Check for proper operation by attem pting to turn key to LOCK position in the various transmission gear range when the vehicle is stationary. Key should turn to LOCK position only when transmission control is in PARK on automatic transmission models or in reverse on manual transmission models. Key should be removable only in LOCK position. b. P A R K IN G B R A K E -C h eck parking brake holding ability by parking on a fairly steep hill and restraining the vehicle with the parking brake only. C A U T IO N : Before making checks (c) or (d) below, be sure to have a clear distance ahead and behind the vehicle, set the parking brake and firmly apply the foot brake. Do not depress accelerator pedal. Be prepared to turn off ignition switch immediately if engine should start. c. STA RTER SA FETY SW ITCH (AUTOM ATIC TR A N SM ISSIO N VEHICLES) -C h eck starter safety switch by attem pting to start the engine with the transmission in each of the driving gears. The starter should operate only in the Park ("P ") or N eutral ("N ") positions. d. STARTER, SA FETY SW ITCH (M A N UAL TRA N SM ISSIO N V EHICLES) - T o check, place the shift lever in neutral, depress the clutch halfway, and attem pt to start. The starter should operate only when clutch is fully depressed. e. TR A N SM ISSIO N SH IFT IN D IC A T O R -C h eck to be sure autom atic transmission shift indicator accurately indicates the shift position selected. f. STEER IN G -B e alert to any changes in steering action. The need for inspection or servicing may be indicated by increased effort to turn the steering wheel, excessive free play or unusual sounds when turning or parking. g. W H EEL A L IG N M E N T A N D BALANCE - I n addition to uneven or abnormal tire wear, the need for wheel alignment service may be indicated by a pull to the right or left when driving on a straight and level road. The need for wheel balancing is usually indicated by a vibration of the steering wheel or seat while driving at normal highway speeds. h. BRAKES -B e alert to illumination of the brake warning light or changes in braking action, such as repeated pulling to one side, unusual sounds either when braking or between brake applications, or increased brake pedal travel. Any of these could indicate the need for brake system inspection a n d /o r service. i. EX H A U ST SYSTEM -B e alert to any change in the sound of the exhaust system or a smell of fumes which may indicate a leak requiring inspection an d /o r service. (See also Engine Exhaust Gas Caution in Item B-3 of this section.) j. W IN D SH IE L D W IPE R A N D W ASHER -C heck operation of wipers, as well as condition and alignment of wiper blades. Check amount and direction of fluid sprayed by washers during use. k. D EFR O STER -C h eck performance by moving controls to "D EF" and noting am ount of air directed against the windshield. 1. R EA R V IEW M IRRO RS A N D SUN VISORS -C h eck that friction joints are properly adjusted so m irrors and sun visors stay in the selected position. m. H O R N -B low the horn occasionally to be sure that it works. Check all button locations. n. LAP A N D SH O U LD ER BELTS -C h e ck belts, buckles, latch plates, retractors, rem inder systems and anchors for proper operation or damage. Check to make certain that anchor m ounting bolts are tight. o. H EA D R ESTRA IN TS —Check that head restraints, if present, adjust properly in the up detent positions, and that no components are missing, damaged or loose. p. SEAT AD JUSTERS -C h e ck that seat adjusters securely engage by pushing forward and backward whenever a manual seat is adjusted. q. SEAT BACK LATCHES -C h e ck to see that seat back latches are holding by pulling forward on the top of each folding seat back. r. LIG H TS A N D BUZZERS -C h e ck all instrum ent panel illuminating and warning lights, seat belt reminder light and buzzer, interior lights, license plate lights, side m arker lights, headlamps, parking lamps, tail lamps, brake lights, turn signals, backup lamps, and hazard warning flashers. Have headlamp aim checked every 12 m onths or 15,000 miles, or more often if light beams seem to be aimed improperly. s. GLASS -C h eck for broken, scratched, dirty or damaged glass on vehicle that could obscure vision or become an injury hazard. TR U C K S UPP - S ER VICE GENERAL IN F O R M A T IO N A N D L U B R IC A T IO N t. D O O R LATCHES --Check for positive closing, latching and locking. u. H O O D LA TCH ES -C h eck to make sure hood closes firmly by lifting on the hood after each closing. Check also for broken, damaged or missing parts which might prevent secure latching. v. F L U ID LEAKS -C h eck for fuel, water, oil or other fluid leaks by observing the ground beneath the vehicle after it has been parked for a while. (W ater dripping from air conditioning system after use is normal.) If gasoline fumes or fluid are noticed at any time , the cause should be determined and corrected without delay because of the possibility of fire. w. SPA RE A N D JA C K -C h e c k that spare tire assembly and jack equipment are securely stowed at all times. B-2 TIRES AND WHEELS - T o equalize wear, rotate tires as illustrated in Section 10. Adjust the tire pressures as recommended on tire placard on rear face of driver’s door. Check disc brake pads and condition of rotors while wheels are removed. Check tires for excessive wear or damage. Make certain wheels are not bent or cracked and wheel nuts are tight. Check tire inflation pressure at least monthly, or more often if daily visual inspection indicates the need. B-3 EXHAUST SYSTEM **~Check complete exhaust system and nearby body areas for broken, damaged, missing or mispositioned parts, open seams, holes, loose connections or other deterioration which could perm it exhaust fumes to seep into the passenger com partm ent. Any defects should be corrected immediately. To help continue integrity, exhaust system pipes and resonators rearw ard of the muffler must be replaced whenever a new muffler is installed. B-4 SUSPENSION AND STEERING -C h eck for damaged, loose or missing parts, excessive wear or lack suspension and steering should be replaced by a or parts showing visible signs of of lubrication in front and rear system. Questionable parts noted qualified mechanic without delay. B-5 BRAKES AND POWER STEERING -C heck lines and hoses for proper attachm ent, leaks, cracks, chafing, deterioration, etc. Any questionable parts noted should be replaced or repaired immediately. W hen abrasion or wear is evident on lines or hoses, the cause must be corrected. B-6 ENGINE DRIVE BELTS **~Check belts driving fan, A IR pump, generator, power steering pump and air conditioning compressor for cracks, fraying, wear and tension. Adjust or replace as necessary. B-7 DRUM BRAKES AND PARKING BRAKE -C heck drum brake linings and other internal brake components at each wheel (drums, wheel cylinders, etc.). Parking brake adjustm ent also should be checked whenever drum brake linings are checked. 0-15 B-8 THROTTLE LINKAGE -C h e ck for damaged or missing parts, interference or binding. Any deficiencies should be corrected without delay by a qualified mechanic. B-9 UNDERBODY - I n geographic areas using a heavy concentration of road salt or other corrosive materials for snow removal or road dust control, flush and inspect the complete underside of the vehicle at least once each year, preferably after a w inter’s exposure. Particular attention should be given to cleaning out underbody members where dirt and other foreign materials may have collected. B-10 BUMPERS -C h eck the front and rear bumper systems at 12-m onth/15,000 mile intervals to be sure that impact protection and clearance originally designed into these systems remain in a state of full readiness. They also should be checked whenever there is obvious bumper misalignment, or whenever the vehicle has been involved in a significant collision in which the bumpers were struck, even when slight or no damage to the bum per systems can be seen. S E C T IO N C E M IS S IO N C O N T R O L M A IN T E N A N C E NOTE: Additional recommended maintenance instructions relating to vehicle use, evidence of maintenance and service replacement parts are included in the New Truck W arranty Inform ation folder. C-1 THERM O STATICALLY CONTROLLED AIR CLEANER -In sp e ct installation to make certain that all hoses and ducts are connected and correctly installed. Also check valve for proper operation. C-2 CARBURETOR CHOKE AND HOSES -C h ec k choke mechanism for proper operation. Any binding condition which may have developed due to petroleum gum formation on the choke shaft or from damage should be corrected. Check carburetor choke hoses for proper connection, cracking, abrasion or deterioration and correct or replace as necessary. C-3 ENGINE IDLE SPEED -A d ju st engine idle speed accurately (following the specifications shown on the label under the hood). Adjustments must be made with test equipment known to be accurate. C-4 EARLY FUEL EVAPORATION (EFE) SYSTEM -C h eck valve for proper operation. A binding condition must be corrected. Check switch for proper operation. Check hoses for cracking, abrasion or deterioration. Replace parts as necessary. NOTE: More frequent brake checks should be made if driving conditions and habits result in frequent brake application. TRUC K SUPP • S ER VIC E 0 -1 6 GENERAL IN F O R M A T IO N A N D L U B R IC A T IO N C-5 CARBURETOR M OUNTING - A t 7,500, 22,500, and 45,000 miles for V8 engines and 7,500, 30,000 for L-6 engines torque carburetor attaching bolts a n d /o r nuts to compensate for compression of the gasket. C-6 VA C U UM ADVANCE SYSTEM AND HOSES -C h eck system for proper operation and hoses for proper connection, cracking, abrasion or deterioration. Replace parts as necessary. C-7 FUEL FILTER .-R e p la c e filter in carburetor at designated intervals or more frequently if clogged. C-8 POSITIVE CRANKCASE VENTILATION SYSTEM (PCV) -C h eck the PCV system for satisfactory operation at 12 m o n th /15,000 mile intervals, and clean filter. Replace the PCV valve at 24 m onth/30,000 mile intervals and blow out PCV valve hose with compressed air. Replace deteriorated hoses. The PCV filter (located in the air cleaner) should be replaced whenever the air cleaner element is replaced. C-9 IDLE STOP SOLENOID -C h eck for proper operation. An inoperative solenoid must be replaced. C-10 SPARK PLUG W IRES -C lean exterior of wires; remove any evidence of corrosion on end terminals. Inspect spark plug wires for evidence of checking, burning, or cracking of exterior insulation and tight fit at distributor cap and spark plugs or other deterioration. If corrosion cannot be removed or other conditions above are noted, replace wire. C-12 T IM IN G AND DISTRIBUTOR CAP -A d ju st ignition timing following the specifications shown on label under the hood. Also, carefully inspect the interior and exterior of the distributor cap and rotor for cracks, carbon tracking and terminal corrosion. Clean or replace as necessary. C-13 EVAPORATION CONTROL SYSTEM (ECS) -Check all fuel and vapor lines and hoses for proper connections and correct routing as well as condition. Remove canister and check for cracks or damage. Replace damaged or deteriorated parts as necessary. Replace filter in lower section of canister. C-14 FUEL CAP, FUEL LINES AND FUEL TANK -In sp ect the fuel tank, cap and lines for damage which could cause leakage. Inspect fuel cap for correct sealing ability and indications of physical damage. Replace any damaged or malfunctioning parts. C-15 AIR CLEANER ELEMENT -R eplace the engine air cleaner element under norm al operating conditions every 30,000 miles. The PCV filter should be replaced at the same interval. Operation of vehicle in dusty areas will necessitate more frequent replacements. CAUTION: Do not operate the engine without the air cleaner unless temporary removal is necessary during repair or maintenance of the vehicle. When the air cleaner is removed, backfiring can cause fire in the engine compartment. C-11 SPARK PLUGS -R ep lace plugs at 22,500 mile intervals for V8 engines and 30,000 miles for L-6 engines with type specified in Section 6 of this manual. TRUC K S U P P - SER VIC E GENERAL IN F O R M A T I O N A N D L U B R IC A T IO N 0-1 7 RECOMMENDED FLUIDS & LUBRICANTS USAGE F L U ID /L U B R IC A N T P o w e r s te e rin g s y s te m a n d p u m p re s e rv o ir G M p o w e r s te e rin g f l u id P a rt N o . 1 0 5 0 0 1 7 — if n o t a v a ila b le use D E X R O N ® - ll a u to m a tic tr a n s m is s io n f l u id o r e q u iv a le n t D if f e r e n t ia l—s ta n d a rd S A E -8 0 W o r S A E -8 0 W -9 0 G L -5 gear lu b r ic a n t (S A E -8 0 W in C an a d a) D if fe r e n t ia l — P o s itr a c tio n L u b r ic a n t G M P a rt N o . 1 0 5 0 0 81 M a n u a l S te e rin g G e a r L u b r ic a n t G M P a rt N o . 1 0 5 1 0 5 2 M a n u a l tra n s m is s io n S A E -8 0 W o r S A E -8 0 W -9 0 G L -5 gear lu b r ic a n t (S A E -8 0 W in C an a d a) B ra k e s y s te m a n d m a s te r c y lin d e r D e lc o S u p re m e N o . 11 o r D O T -3 f lu id s C lu tc h lin k a g e (M a n . tra n s . o n ly ) a. P iv o t p o in ts b. Push ro d to c lu t c h f o r k j o in t , a n d cro ss s h a ft p re ssu re f i t t in g E n g in e o il Chassis grease m e e tin g r e q u ire m e n ts o f o f G M 6 0 3 1 -M M a n u a l tra n s m is s io n s h if t lin k a g e , c o lu m n s h if t E n g in e o il S h if t lin k a g e , f l o o r s h if t E n g in e o il H o o d L a tc h a s s e m b ly a. P iv o ts a n d s p rin g a n c h o r b . Release p a w l E n g in e o il Chassis grease H o o d h in g e s E n g in e o il A u to m a tic tra n s m is s io n s h if t lin k a g e E n g in e o il Chassis lu b r ic a t io n C hassis grease m e e tin g r e q u ire m e n ts o f G M 6 03 1 -M C o n s ta n t V e lo c ity U n iv e rs a l J o in t G M L u b r ic a n t P a rt N o . 1 0 5 0 6 7 0 o r grease m e e tin g re q u ir e m e n ts o f G M -6 0 4 0 -M A u to m a tic tra n s m is s io n D E X R O N ® - ll a u to m a tic tr a n s m is s io n f lu id P a rk in g b ra k e cables C hassis grease F r o n t w h e e l b e a rin g s W h e el b e a rin g lu b r ic a n t G M P a rt N o . 1 0 5 1 3 4 4 o r e q u iv a le n t B o d y d o o r h in g e p in s , fu e l d o o r h in g e , ta ilg a te h in g e s E n g in e o il W in d s h ie ld w a s h e r s o lv e n t G M O p tik le e n w a s h e r s o lv e n t P a rt N o . 1 0 5 1 5 1 5 o r e q u iv a le n t B a tte ry C o lo rle s s , o d o rle s s , d r in k in g w a te r E n g in e c o o la n t M ix tu r e o f w a te r a n d a h ig h q u a lit y E th y le n e G ly c o l base ty p e a n ti-fre e z e c o n f o r m in g to G M S p e c. 1 8 9 9 -M TRUC K SUPP - S E R VIC E 0 -1 8 GENERAL IN F O R M A T IO N A N D L U B R IC A T IO N DRIVE ON HOIST HH BUMPER JACK LIFTING jjj FLOOR JACK OR HOIST LIFT Fig. 6--G M o d e l Liftin g Points TR U C K SUP P - SER VIC E GENERAL IN F O R M A T I O N A N D L U B R IC A T IO N L u b ric a tio n Period N o. L u b rica tio n Points 1 5 6 7 L o w er C o n tro l A rm s U p p er C o n tro l A rm s U p p er and Lo w er C o n tro l A rm Ball Joints In te rm e d ia te Steering S h a ft (P A 1 0 ) T ie R od Ends W heel Bearinqs Steering Gear 7 ,5 0 0 M iles 3 0 ,0 0 0 M iles 3 0 ,0 0 0 M iles 8 A ir C leaner — E lem en t 3 0 ,0 0 0 Miles 2 3 4 Chassis L u b ric a n t Chassis L u b ric a n t Chassis L u b ric a n t 4 places as requ ired 4 places as requ ired 4 places as requ ired 7 ,5 0 0 M iles Chassis L u b ric a n t 2 places as requ ired Chassis L u b ric a n t W hl. Brq. L u b ric a n t 4 places as requ ired 2 places as required M aster C y lin d e r 7 ,5 0 0 M iles 12 Transm ission — M anual - A u to m a tic T h ro ttle Bell C rank — L-6 C a rb u re to r Linkage — V -8 Brake and C lutch Pedal Sprinqs Universal Joints P ro peller S h a ft S lip J o in t Rear A x le 7 .5 0 0 7 .5 0 0 7 ,5 0 0 7 ,5 0 0 7 ,5 0 0 16 17 18 Q u a n tity 7 ,5 0 0 Miles 7 ,5 0 0 M iles 7 ,5 0 0 M iles 11 13 14 15 Type of L u b ric a tio n M iles M iles M iles M iles Miles 7 .5 0 0 M iles 7 ,5 0 0 M iles 7 ,5 0 0 M iles Delco S uprem e N o . 11 or D O T -3 flu id s G L -5 D e x ro n ® H or equivalent Enqine O il Enqine O il Engine O il As required Chassis L u b ric a n t Chassis L u b ric a n t G L -5 As required As required As required As As As As As required required required required required 0 -1 9 Rem arks C heck fo r Grease L e a k — D o n o t Lu b rica te R ep lace—See V eh icle M ain te n an ce S chedule C heck — add flu id w hen necessary Keep even w /fille r plug. See L u b ric a tio n S ection N o t shown Check See L u b ric a tio n section Fig. 7 --L u b ric a tio n - C o n v e n tio n a l M o d e ls - L ig h t D uty E m ission S ystem s TR U C K SUPP - S E R VIC E 0-20 N o. 1 2 3 4 b 6 8 GENERAL IN F O R M A TIO N A ND LUBRICATIO N Lu b rica tio n Points C on trol A rm Bushings and Ball Joints T ie Rod Ends Wheel Bearings Steering Gear C lutch Cross-Shaft Trans. C o n tro l S h aft A ir C leaner—E lem ent L u b ricatio n Period 7 ,5 0 0 7 ,5 0 0 3 0 ,0 0 0 3 0 ,0 0 0 7 ,5 0 0 7 ,5 0 0 3 0 ,0 0 0 M iles M iles Miles Miles Miles Miles M iles 9 10 T ransmission—Manual —A u to m a tic Rear A x le O il F ilte r 11 Brake M aster C ylin d e r 7 .5 0 0 Miles 7 .5 0 0 M iles 7 ,5 0 0 Miles Every Second O il Chanqe 7 ,5 0 0 Miles 12 Parking Brake Linkage 7 ,5 0 0 M iles Type of L u brication Q u a n tity Chassis L u bricant Chassis Lu b rica n t W hl. Brg. L u b rica n t 12 places as required 4 places as required 2 places as required Chassis L u b rica n t Chassis L u bricant As required As required G L -5 D exron ® -II or Equivalent G L -5 As required As required As required D elco Suprem e N o . 11 or D O T -3 fluids Chassis L u bricant As required Rem arks 2 fittin q s each side See V eh icle M aintenan ce Schedule See L u b rica tio n Section See L u b rica tio n S ection See L u b rica tio n S ection C h e ck—A d d flu id w hen necessary L u b rica te Linkage and Cables Fig. 8 -L u b ric a tio n - 1 /2 Ton G M o d e ls T R U C K SUP P - S ER VICE S E C TIO N 1A HEATER AND AIR CONDITIONING C O N T E N T S OF T H IS S E C TIO N General Inform ation........................................................................... A ir C onditioning................................................................................. 1A-1 1A-1 GENERAL INFORMATION Refer to the 1974 Light Duty Truck Service M anual for servicing the standard heater and auxiliary heater except as follows: AUXILIARY HEATER - W IRING DIAGRAM Refer to section 12 of this manual for auxiliary heater wiring diagram. AIR CONDITIONING Refer to the 1974 Light Duty Truck Service M anual for servicing an air conditioning system with a V8 engine or six cylinder engine except as follows: M A IN U N IT S OF THE S Y S T E M AXIAL SIX CYLINDER COMPRESSOR (Fig. 1) Teflon Piston Ring Type Pistons Axial six cylinder compressors used on 1975 and 1976 vehicles are equipped with a Teflon ring type piston (Fig. 2), instead of the former Carbon ring type. The basic compressor mechanism remains unchanged. The Teflon ring type piston is dimensionally the same as the carbon ring type except for the ring groove detail. The replacement procedure for the Teflon ring type piston differs from that of the carbon ring type. Refer to the Overhaul section of this manual for the proper method of replacing the Teflon ring type pistons or Teflon piston rings. RADIAL FOUR CYLINDER COMPRESSOR A radial four cylinder compressor (Fig. 3) is used on a vehicle with a six cylinder engine. The compressor brackets (Fig. 4) electromagnetic energized by the is mounted to the engine by mounting and is belt driven by the engine when the clutch assembly on the compressor is air conditioning controls. The purpose of the compressor is to pump low pressure, low tem perature refrigerant vapor produced by the evaporator and compress it into a high pressure, high tem perature vapor which can then be readily condensed back to a liquid state by the condenser. The compressor has a displacement of 10.0 cu. in. The compressor has variations in the pulley rim diameter specified for the respective vehicle applications. The basic compressor mechanism is a modified scotch yoke with four cylinders located radially in the same plane. Opposed pistons are pressed into a yoke which rides upon a slider block located on the shaft eccentric. Rotation of the shaft provides reciprocating piston motion with no "connecting rods". The mechanism is completely balanced with counterweights. Needle bearings are used for the shaft journals and the shaft eccentric. Pistons and yokes, along with the main cylinder housing and front cover, are made from aluminum to provide light weight. Teflon piston rings are used to provide both a gas compression seal and a piston-to-bore bearing surface. The outer shell is a simple steel band which encloses a large annular discharge muffler space. Two O-rings provide a seal between the compressor shell and the compressor cylinder. A rubber seal ring seals the front head to the cylinder assembly and the shaft seal assembly provides a front head to shaft seal. Refrigerant flows into the crankcase from the connector block at the rear, is drawn through the reeds attached to the piston top during the suction stroke, and is discharged outward through the discharge valve plate which is held in place at the top of the cylinder by a snap ring. Discharge gas flows out of the compressor muffler cavity through the connector block at the rear. TRUC K SUP P - S E R VIC E 1A-2 HEATER O -R ing Front H ead Shaft Seal Assembly AND Seal Seat S w itch Retainer Ring O -R ings Seal Seat Retainer Ring A bsorbent Sleeve Seal Retainer Clutch Coil Retainer Ring / O -R ing 0 “ Ring , Compressor Shell Clutch Coil and Housing Assembly Suction Screen Fig. 1 -A x ia l Six Cylinder Com pressor Exploded Pulley Inner Oil Pump Gear Bearing O il Pick-up Tube I S w itch O -R ing AIR CONDITIONING Pressure Relief V alve \ Bearing Retainer O - Ring Pulley Retainer Ring Lock Nut Rear Head O uter O il Pump G e a r Clutch Plate and Hub Assembly j Retainer Ring ^ Rear Discharge V alve Plate Assembly Lock Nut Rear Suction Reed Bushing Needle Bearing O - Ring Rear Cylinder H alf Teflon Piston Ring Ball V ie w Shoe Disc T e flo n R ing T ype Piston T e flo n Piston Ring Shaft Discharge Crossover Tube Thrust Races Front Suction Reed Front Discharge V alve Plate Assembly HEATER A N D A IR C O N D IT IO N IN G 1A-3 contains all necessary replacement parts for field service. Front Head The front head contains the front main shaft bearing pressed in place and a drilled oil hole for lubrication to the shaft seal cavity. The front head is mounted to the cylinder assembly by four screw and washer assemblies. Thrust Washers Fig. 2 - T e f lo n Ring T y p e Piston Clutch Coil The clutch coil is molded into the steel coil housing and must be replaced as a complete assembly. Three protrusions on the rear of the housing fit into alignment holes in the compressor front head. The coil is secured to the front head by a pressed fit between the coil housing and neck portion of the front head. The coil has 3.65 ohms resistance at 80°F. ambient and will require no more than 3.2 amperes at 12 volts D.C. The clutch coil has two term inals for the power and ground leads. Clutch-Pulley The movable part of the clutch drive plate is in front of and adjacent to the rotor and bearing assembly. The arm ature plate, the movable member, is attached to the drive hub through driver springs riveted to both members. The hub of the drive plate is pressed on the compressor shaft and keyed to the shaft by a square drive key. A self-locking nut threads on the end of the shaft and is tightened against the shaft. The rotor and hub is a welded assembly and contains six threaded holes for mounting the pulley rim. The pulley rim is secured to the rear portion of the rotor by six screws and six special lock washers. A two-row ball bearing is pressed into the rotor hub and held in place by three punch stakes, 120° apart, into the rotor hub near the hub bore. The entire clutch coil, pulley rim, rotor and bearing assembly is pressed on the front head of the compressor and secured by a retainer ring. W hen power is supplied to the clutch coil the arm ature plate of the drive plate and hub assembly electromagnetically engages the slotted portion of the rotor face which then drives the crankshaft through the drive plate leaf springs and hub. Shaft Seal The main shaft seal, located in the neck of the compressor front head, consists of the seal assembly with its ceramic seal face in a spring loaded cage. An "O" ring seal, located within the ceramic seal, provides a seal to the shaft surface. The contact surface of the shaft seal seat is finished to a high polish and m ust be protected against nicks, scratches and even fingerprints. Any surface damage will cause a poor seal. An "O" ring, located in an internal groove in the neck of the front head provides a seal with the outer diameter of the seal seat. A retainer ring, tapered side away from the seat, secures the seat in place. The hub and arm ature plate must be removed to gain access to the seal. A shaft seal kit One thrust washer is used on the rear end of the crankshaft between the rear eccentric and the rear of the cylinder. A belleville washer, sandwiched between two thrust washers at the front of the shaft between the front eccentric and the front head controls the lateral thrust tolerance of the shaft and cylinder assembly. The two thrust washers have tangs and are assembled with the tangs facing inward to engage and cause the thrust and belleville washer assembly to rotate as a unit and not separately. OIL CHARGE Refer to the oil charge chart in Figure 5 for A-6 and R-4 compressor oil charge. SYSTEM CONTROLS General 1976 CK Series Truck (Fig. 6) Heating and Air Conditioning mode selection has been simplified by the addition of a new “Maximum Mode position” to the previous six mode control. With the Temperature lever set to the extreme cold position and the mode selector lever positioned in MAX, maximum cooling is attained, and High blower speed is automatically selected. The new “MAX” mode setting as well as the other cooling settings (NORM and BI-LEVEL) have been grouped under an A/C heading. The VENT and HEATER settings have been grouped under an ECONOMY heading. Selector Lever The system selector lever (air control lever) determines the mode of operation: W hen the system selector lever is placed in A /C (M AX, N O R M or BI-LEVEL) or D E F positions, electrical circuit connection is made to the compressor clutch through the control panel switch and the compressor discharge pressure switch. If the compressor discharge pressure switch is closed (ambient tem perature above approximately 42°F, the compressor will run. In the O FF, or ECON OM Y (VENT or H EA TE R ) positions the compressor clutch is not energized. The system selector lever also determines the direction of outlet air flow. Moving the lever from mode to mode varies the position of a vacuum valve on the control. The position of the vacuum valve will supply vacuum to, or vent, vacuum diaphragms which position the upper and lower mode and defroster air doors in the selector duct assembly. The position of these air doors determines if output air flow is from the heater purge outlet at O FF, the heater outlet with slight air flow from defroster nozzles at H EA TER, heater and A /C outlets at VENT, A /C outlets only at M AX and NORM , heater A /C and defroster outlets at BI-LEVEL, or the defroster outlets with slight airflow from the heater outlet at DEF. TRUC K SUPP - S ER VIC E 1 A-4 HEATER A N D AIR C O N D IT IO N IN G 1. Screw 13. S upe rhea t Switch 24. B e lle v ille W ashe r 2. Locking W ashe r 14. O -R ing 25. O -R ing 3. P ulley Rim 15. Pressure R elief V alve 26. S hell Assy. 4. C o il an d H ousing Assy. 16. O -R ing 17. Screw 18. S h ip p in g P late 19. O -R ing 27. Ring Seal 28. M a in B e a rin g 29. Front H e a d Assy. 5. Rotor B e a rin g 6. Rotor a n d B e a rin g Assy. 7. R e ta in in g Ring 8. C lutch Drive Assy. 9. C lutch H ub Key 10. S h a ft N u t 11. C ap 12. R e ta in in g Ring 20. R eta in ing Ring 21. V alve P late Assy. 22. C y lin d e r and S h a ft Assy. 23. Thrust W ashe r 30. Screw a n d W a sh e r 31. O -R ing 32. S h a ft Seal 33. Seal Seat 34. R e ta in in g Ring Fig. 3 --R a d ia l Fo ur C y lin d e r C o m p ress o r-E xp lo d e d V ie w W hen the system is in M AX A /C mode and the tem perature lever is at full COLD the air inlet door is positioned to reduce the supply of outside air from approximately 100 percent to approximately 20 percent. The rem ainder of the air input (80 percent) to the A /C system is then taken from the interior of the passenger compartm ent. This recirculation of interior air (recirc operation) provides a source of fast cool down of interior temperatures. A switch connected to the selector lever overrides the blower (FA N ) switch, (in M AX A /C ) and automatically provides high blower speed. Temperature Control Lever The tem perature lever determines the tem perature of outlet airflow by positioning the tem perature door in the selector duct assembly, through the motion of a bowden cable linking the control panel lever to the tem perature door. NOTE: A n engine therm al switch prevents LO blower operation until the tem perature at the switch reaches 95°F. This blower delay can be by-passed by placing TRUC K S U P P - S ER VIC E HEATER A N D AIR C O N D IT IO N IN G 1A-5 control of blower speed. To provide constant ventilation, the blower m otor electrical circuitry prevents the blower m otor from being shut off when the ignition switch is on. Therefore, the blower speeds available are H I, LO and two medium speeds. The control panel also has a "recirc. override" switch (part of the master switch) which overrides the blower speed switch and autom atically provides H I blower speed when the system selector lever is in M AX and the tem perature lever is set to full COLD. System Operation - CK Truck System operation is as illustrated in Fig. 7. Vacuum Schematic - CK Truck The CK Truck air conditioning vacuum schematic is illustrated in Figure 8. Rear A/C Blower Motor - C69 G Van the fan switch in any of the other three positions. Fari Switch The blower FA N switch provides a means of selecting the am ount of airflow from the system by regulating the speed of the blower motor. There are, however, limitations to the When air circulation only is desired, the rear A /C blower m otor may be operated independent of the front A /C blower m otor and without the cooling function. The rear blower m otor resistor has been relocated to a position on the blower shroud at the rear of the vehicle. See Section 12 of this manual for A /C blower m otor and heater blower m otor (A /C equipped vehicles only) wiring diagram revisions for 1976. T R U C K SUPP - S E R V IC E 1 A-6 HEATER A N D AIR C O N D IT IO N IN G UNIT ADD OIL CONDENSOR .................................. EVAPORATOR .............................. EE -V IR .......................................... COMPRESSOR CONDITION ...............................................1 OUNCE AMOUNT OF OIL DRAINED FROM COMPRESSOR REPLACING COMPRESSOR WITH A NEW COMPRESSOR. MORE THAN - 4 OZ. IN A-6 - 1/2 OZ. IN R 4 LESS THAN - - REPLACING COMPRESSOR WITH A SERVICE REBUILT COMPRESSOR. 4 OZ. IN A-6 1/2 OZ. IN R-4 MORE THAN - 4 OZ. IN A-6 - 1/2 OZ. IN R-4 LESS THAN - 4 OZ. IN A-6 - 1/2 OZ. IN R-4 UNABLE TO RUN COMPRESSOR BEING REPLACED, PRIOR TO REMOVAL FROM CAR. - 1-1/2 OZ. IN A-6 - 1/2 OZ. IN A-6 AND SYSTEM APPEARS TO HAVE LOST LITTLE OR NO OIL LESS THAN - 1-1/2 OZ. IN A-6 - 1/2 OZ. IN R-4 OR SYSTEM APPEARS TO HAVE LOST MAJOR AMOUNT OF OIL. CONTAMINATED OIL DRAINED FROM SYSTEM. ANY AMOUNT MORE THAN AMOUNT OF OIL TO INSTALL *DRAIN NEW COMPRESSOR, REFILL WITH NEW OIL (SAME AMOUNT AS DRAINED FROM OLD COMPRESSOR). **DRAIN NEW COMPRESSOR. INSTALL NEW OIL IN NEW COMPRESSOR - 6 0Z. IN A-6 - 3 OZ. IN R-4 *SAME AS ABOVE PLUS AN ADDITIONAL OUNCE (MORE OIL IS RETAINED IN A DRAINED COMPRESSOR THAN ONE THAT HAS BEEN REBUILT). **SAME AS ABOVE PLUS AN ADDITIONAL OUNCE. *SAME AS ABOVE. **SAME AS ABOVE. DRAIN AS MUCH OIL AS POSSIBLE FROM SYSTEM. FLUSH SYSTEM WITH REFRIGERANT-11. REPLACE DRIER DESSICANT AND INSTALL NEW 525 VISCOSITY OIL IN NEW COMPRESSOR: A-6 COMP. 10-1/2 OZS. R-4 COMP. 6 OZS. Fig. 5--C o m p resso r Oil C h a rg e fo r A -6 and R-4 U n it R e p la c e m e n t TRUC K SUP P - SER VIC E HEATER A N D A IR C O N D IT IO N IN G 1A-7 Fig. 6 --H e a te r A ir C o n d itio n in g C o n tro l A s s e m b ly - CK T ru c k SYSTEM OPERATION - CK TRUCK S ELE C TO R LE V E R P O S ITIO N COMPRESSOR BLOW ER SPEEDS A V A IL A IR SOURCE A IR EN TER S V E H IC L E H E A T E R A /C DOOROPEN TO: HEATER D E FR O S TE R D O O R -O P E N TO: HEATER O FF O FF LOW O U T S ID E FLO O R O U T L E T S HEATER M A X A /C ON HI INSI DE% D ASH O U T L E T S A /C HEATER N O R M A /C ON A LL O U T S ID E DASH O U T L E T S A /C HEATER B I-L E V E L ON ALL O U T S ID E FLO O R A N D DASH O U T L E T S A /C & HEATER HEATER VENT O FF A LL O U T S ID E D ASH O U T L E T S A /C HEATER H TR O FF A LL O U T S ID E FLO O R O U T L E T S HEATER HEATER HEATER D E FR O S T D E FR O S T O U T L E T S O U T S ID E ALL ON D EF NO TE % 100% Inside air is n o t available, some bleed throug h o f outside air is allow ed. Fig. 7--S ystem O p e ra tio n - CK T ru c k Fig. 8--A ir C o n d itio n in g V a c u u m S c h e m a tic - CK T ru c k TRUC K SUP P - SER VIC E 1A-8 HEATER A N D AIR C O N D IT IO N IN G SERVICE OPERATIONS CONDENSER - CK MODEL THERMOSTATIC SW ITCH - CK TRUCK The location of the therm ostatic switch has been changed to provide more accurate sensing of refrigerant tem perature and as a result improved system response and control. The sensing element is attached by means of a clamp to the inlet tube of the evaporator. The switch body is mounted on the bracket which supports the inlet tube in position at the evaporator case. Replacement 1. Disconnect the battery ground cable. 2. Disconnect connector. the electrical harness at the switch 3. Remove the screw attaching the sensing element clamp and remove the clamp. Insulating material around sensing element may be removed at this point. 4. Remove the two screws attaching the switch body to the evaporator inlet line bracket and remove the switch and sensing element. 5. To replace reverse steps 1 to 3. Fig. 9 --C o n d e n s e r In s ta lla tio n (C-K M o d e ls ) Replacement (Fig. 9) NOTE: Insulating m aterial removed from sensing element must be replaced with a suitable insulating compound. When replacing sensing element clamp tighten screw securely enough to provide intimate contact between sensing element and inlet tube. Do NOT over tighten. 1. Disconnect battery ground cable. HEATER AIR DISTRIBUTOR 2. Purge the system of refrigerant. AND EXTENSION DUCT - G MODEL 3. Remove the grille assembly. Replacement 4. Remove the radiator grille center support. 5. Remove the left grille support to upper fender support (2) screws. 6. Disconnect the condenser inlet and outlet lines and the outlet tube line at the right end of the condenser. Cap or plug all open connections at once. 1. Disconnect battery ground cable. 2. Remove engine cover. 3. Remove evaporator-blower shield. 4. Remove shield bracket. 5. Remove left floor outlet deflector and bracket. 7. Remove the condenser to radiator support screws. 6. Loosen steering column to instrum ent panel reinforcement screws. Remove one screw. Torque both screws on installation. 8. Bend the left grille support outboard to gain clearance for condenser removal. 7. Disconnect speedometer cable at meter. 9. Remove the condenser assembly by pulling it forward and then lowering it from the vehicle. 10. To install a new condenser, reverse Steps 1-9 above. Add one fluid ounce of clean refrigeration oil to a new condenser. NOTE: Use new "O" rings, coated with clean refrigeration oil, when connecting all refrigerant lines. 11. Evacuate, charge and check the system. 8. Remove instrum ent panel to lower reinforcement attaching screws. 9. Move instrum ent panel assembly rearward. Disconnect radio antenna and electrical connector. Support instrum ent panel at right visor. Disconnect electrical connector at brake switch. 10. Remove blower-evaporator support bracket to door pillar and forward engine housing attaching screws. Move rearward to gain access. T R U C K S UPP - SER VIC E HEATER A N D AIR C O N D IT IO N IN G 1A-9 11. Disconnect vacuum lines and electrical connectors. Remove heater distributor duct assembly. 12. Transfer duct and relays. 13. To reassemble, Reverse Seps 1-12. HEATER CORE CASE AND CORE - G MODEL Replacement Follow Steps 1-10 of "H eater A ir D istributor and Extension D uct Replacement" procedure. 11. Remove battery. 12. Disconnect heater hoses at heater core (drain pan below hoses) refill radiator upon completion. 1 13. Remove air inlet valve assembly. A 14. Remove tem perature door control cable at heater case. il 15. Remove heater assembly. t ► 16. Remove heater core. Reseal heater case. 4 AIR INLET VALVE - G MODEL Replacement * 1 Follow Steps 1-10 of "H eater A ir D istributor and Extension D uct Extension D uct Replacement" procedure. 11. Remove duct assembly. Disconnect vacuum hose. Fig. 10--E xp a n sio n T u b e - CK M o d e l 12. Remove vacuum valve. 13. To reassemble, Reverse Steps 1-12. TEMPERATURE DOOR CABLE - G MODEL Replacement Follow Steps 1-10 of "H eater A ir D istributor and Extension D uct Replacement" procedure. 11. Disconnect tem perature door control cable at heater case. 12. Disconnect tem perature door control cable at control. 13. Make up new cable. 14. To reassemble, Reverse Steps 1-13. EXPANSION TUBE - CK MODEL (FIG. 10) A new type expansion tube is incorporated into the air conditioning systems of 1976 CK series trucks. Removal (Fig. 11) 1. Purge the system of refrigerant. 2. Disconnect the condenser to evaporator line at the evaporator inlet. 3. Using needle nose pliers, and gripping the plastic tip of the expansion tube, remove the expansion tube and "O" ring from the core inlet line. Installation 1. Insert the new expansion tube into insertion tool J-26549 as illustrated in figure 12. 2. Coat a new expansion tube "O" ring with clean 525 viscosity refrigeration oil. 3. While slightly compressing the fingers of the tool around the body of the expansion tube (to facilitate entry into the inlet line) insert the expansion tube into the core inlet line and push until the tube reaches a firm stop. This will indicate proper seating of the "O" ring in the inlet line. TRUC K SUPP - SER VICE SECTION 1B TRUCK BODY NOTE: Except for the items listed below, all information found in section IB of the 1974 Light D uty Truck Service Manual is applicable to 1976 Light D uty Trucks. IN D E X C-K M o d els.......................................................................................... G M odels.............................................................................................. IB-1 1B-3 C-K MODELS Fig. 1 -C o w l V e n t V a lv e s COWL VENT VALVES Two styles are shown in figure 1. Removing the attaching screws allows removal of the valve from the side panels. Refer to page IB-6 o f the 1974 manual. Together, this allows proper alignment of the glass to the rear glass run channel for full up and down travel. Refer to pages IB-14 and IB-15 of the 1974 manual. REAR DOOR CHECK STRAP Model 06 REAR SIDE DOOR (MODELS 06 AND 03) Glass Run Channel Adjustment Figure 2 illustrates the front run channel. A t the lower end, a slotted bracket provides for in-and-out adjustment. The screw and locknut at that bracket allow fore-and-aft adjustment. Figure 3 shows the cloth check strap used for rear doors. The door may be completely opened by removing the strap pin from the bracket. The bracket attaches to the pillar with three screws; the strap is fastened to the door panel with two screws and an attaching bar. Refer to page IB-18 of the 1974 manual. TR U C K SUPP - SER VIC E 1B-2 BODY Fig. 4 - W e d g e and S trik e r A d ju s tm e n ts REAR DOOR-STRIKER AND WEDGE ADJUSTM ENTS Figure 4 illustrates the rear door latch strikers and door wedges. Be sure that adjustm ents are as shown to insure proper latching of the rear doors. Refer to page IB-18, figure 48 o f the 1974 manual. ENDGATE DISASSEMBLY Step 10 defines the proper method of removing the regulator on an electric-powered window. The following CA U TIO N emphasizes the need for following step 10 carefully: CAUTION: Step 10 must be performed i f the window is removed or disengaged from the regulator lift arms. The lift arms are under tension from the counter-balance spring, and can cause injury if the motor is removed without locking the sector gears in position. Model 0 6 Refer to page IB-20 of the 1974 Light Duty Truck Service Manual. T R U C K SUPP • S ER VICE BODY 1B-3 G MODELS Fig. 5 --R em o te C o n tro l and Latch es REAR DOOR ITEMS Latches, Strikers and Wedges Figures 5 and 6 illustrate the new latches, strikers, wedges and adjustm ent dimensions for G-M odel rear doors. Refer to pages IB-44 and IB-45 o f the 1974 Light Duty Truck Service Manual for replacement instructions. Note the new dimensions for striker adjustments. QUICK RELEASE BENCH SEAT - G VAN (Fig. 7) All models equipped with 2nd, 3rd and 4th bench seat assemblies feature a quick release mechanism which facilitates removal of the seats for added cargo space. Instead of the conventional clamp and bolt method of seat retention, cam type latch assemblies and hooked retainers, which fit onto anchor pins in floor anchor plates are used. When the latch assemblies are depressed, their cams and the hooks of the retainers are drawn tightly onto the anchor pins for secure seat attachm ent. Removal is accomplished using the following procedure: 1. Pull up on quick release latches located at lower front of seat legs (right and left hand sides). 2. Tilt up front of seat and push seat rearward to clear anchor pins located beneath floor at front and rear of seat legs. 3. Lift seat up and remove from van. 4. To replace, reverse steps 1 to 3. C A U T I O N : When replacing sea ts make sure tha t sea t retainer hooks are fully engaged with anchor pins and latching assembly is fully depressed into place. TRUC K SUP P - S E R VIC E S E C T IO N 2 FRAME Truck frames are essentially carryover, with some models undergoing configuration and alignment reference dimension changes. redesigned. This design change has necessitated moving the kick-up back approximately three inches. On C107 and 109 models, due to shifting the position of the catalytic converter, the left hand converter rail has been The 10-30 series frames and related dimensions are shown in figures 1 through 3. Model A CA107 13-3/8 15-1/4 16 19-7/8 12 CA109 13-3/8 15-1/4 16 19-7/8 12 CA209 13-3/8 15-1/4 17 CA210 310 13-3/4 15-1/4 16 B C D E F G H 1 J K 13 10 14-7/8 13 10 14-7/8 17-3/4 17-3/4 17-3/4 17-3/4 19-7/8 12 13 10 14-7/8 17-3/4 18-1/2 10 13 10 14-1/4 17-3/4 L M N P 19-7/8 16-3/4 15-5/8 17-3/4 69-5/8 19-7/8 16-3/4 15-5/8 17-3/4 69-5/8 17-3/4 19-7/8 16-3/4 15-5/8 17 3/4 17-3/4 19-7/8 15-5/8 17-3/4 S R T U V 76-1/2 110 16-7/8 16-7/8 14 86-1/2 120 16-7/8 16-7/8 14 69-5/8 86-1/2 120 16-7/8 16-7/8 14 69-7/8 105 131 16-7/8 16-7/8 14 155-1/2 CA314 13-3/8 14-7/8 16 18-1/2 10 13 10 14-1/4 17-3/4 17-3/4 19-7/8 15-5/8 17-3/4 69-7/8 129 16-7/8 16 7/8 14 KA107 13-3/8 15-1/4 17 19-7/8 12-1/2 13 10 14-7/8 17-3/4 17-3/4 19-7/8 16-3/4 15-5/8 17-3/4 69-5/8 76-1/2 110 16-7/8 16-7/8 14 KA109 209 13-3/8 15-1/4 17 19-7/8 12-1/2 13 10 14-7/8 17-3/4 17-3/4 19-7/8 16-3/4 15-5/8 17-3/4 69-5/8 86-1/2 120 16-7/8 16-7/8 14 PA 100 7-5/8 9-3/8 11 14-5/8 9-1/2 13 10 PA208 308 7-5/8 9-3/8 11-5/8 14-5/8 9-1/2 13 10 9-1/2 PA210 310 7-5/8 9-3/8 11-5/8 14-5/8 9-1/2 13 10 9-1/2 9-1/2 13 10-7/8 13 71-7/8 36 89 16-7/8 16-7/8 14 13 9-1/2 13 10-7/8 13 72-1/4 59 131 16-7/8 16-7/8 14 9-1/2 13 9-1/2 13 10-7/8 10-7/8 13 71-7/8 67 153 16-7/8 16-7/8 14 9-1/2 13 9-1/2 14 PA314 7-5/8 9-3/8 11-5/8 14-5/8 13 10 13 10-7/8 10-7/8 13 71-7/8 91 177 16-7/8 16-7/8 CA105 13-3/8 15-1/4 17 19-7/8 12 13 10 14-1/4 20 17-3/4 15-5/8 17-3/4 69-5/8 46 88 16-7/8 16-7/8 14 KA105 PE 31132 (137) PE 31432 (157) 13-3/8 15-1/4 17 19-7/8 12-1/2 13 10 14-1/4 20 17 3/4 15-5/8 17-3/4 69-5/8 46 88 16-7/8 16-7/8 14 9-1/8 11-1/2 10-7/8 9-1/2 13 10 9-1/2 13 9-1/2 13 10-7/8 10-7/8 13 68-1/2 71 157 16-7/8 16-7/8 14 9-1/8 11-1/2 10-7/8 9-1/2 13 10 9-1/2 13 9-1/2 13 9-7/8 10-7/8 13 68-1/2 92-1/2 178-1/2 16-7/8 16-7/8 14 9-1/8 11-1/2 10-7/8 9-1/2 13 10 9-1/2 13 9 1/2 13 10-7/8 10-7/8 13 68-1/2 112 240-3/16 16-7/8 16-7/8 14 PE 31832 Fig. 1 -C -K -P T ru c k R efe re n ce D im en s io n s T R U C K SUPP - S ER VIC E 2-2 FRAME T R U C K SUP P - S ER VIC E FRAME 2-3 Fig. 3 --G -V an T ru c k Fram e R efe re n ce D im en s io n s TRUC K SUPP ■ S ER VIC E S E C T IO N 3 FRONT SUSPENSION GENERAL INFORMATION Front suspension design and geometry are basically similar to 1974. Except for the items listed on these pages, all information in Section 3 of the 1974 Light Truck Service Manual is applicable to 1976 Light Trucks. Refer to the Specifications section of this m anual for complete torque values, capacities, tolerances, alignment data, etc. MAINTENANCE AND ADJUSTMENTS ALIG NM ENT NOTE - ALL SERIES K-SERIES TRUCK FRONT WHEEL F ront end alignment directions are given beginning on page BEARINGS AND SPINDLE BEARINGS 3-13 of the 1974 Light Truck Service Manual. It is good Whenever front wheel bearings are lubricated, the spindle needle bearings should also be lubricated, with the same chassis grease. U nder normal conditions, the lubrication interval should be 12,000 miles; off-road use such as in mud or water will require shorter intervals. practice to set front-end values to specifications while the vehicle is in its normally loaded condition. Trucks which are consistently operated under heavy load conditions should have toe-in adjusted w ith the truck under heavy load . This procedure should result in longer tire life. Figure 1 shows the bearings. The spindle bearings are accessible after removing the spindle, shown in figure 2. Refer to page 3-44 of the 1974 Light Truck Service M anual for details. CAMBER AND CASTER A D JU S TM E N TREMOVAL OF SHIM PACKS G 10-30, C10-30 The following procedures should assist in alignment. G 10-20 Models, C 10 Models w ith 3 /4 " Nut: W ith vehicle on front end rack, jack at frame and raise the wheel off the ground. This will allow the upper control arm to drop down far enough to use a socket on the nuts and permit shim removal. G30 Models, C 20 and 30 Models w ith 7 /8 " Nut: Remove the upper control arm rubber bumper; then follow same procedure as above. Reinstall bum per when alignment procedure is completed. Fig. 1--H ub C ro ss-S e ctio n TR U C K SUPP - S E R V IC E 3-2 FRO NT SUSPENSION Fig. 2--R em o vin g S p in d le FRONT A XLE- BALL JOINT ADJUSTM ENT The ball joint adjustment procedure found on page 3-39 of the 1974 Light Truck Service M anual should be modified in step 3 to read: 3. Apply a fish-scale to the tie rod m ounting hole of the steering knuckle arm. W ith the knuckle assembly in the straight-ahead position, determine the right angle pull required to keep the knuckle assembly turning after initial break-away. This pull should not exceed 33 lbs. for each knuckle assembly, in either direction. TRUC K SUPP - SER VIC E S E C TIO N 4 REAR SUSPENSION, PROPSHAFT AND AXLE GENERAL INFORMATION R ear suspension design is basically similar to 1974. The axle chart, figure 1, shows the application of specific axles to the various truck models. Except for the items on the following pages, all information in Section 4 o f the 1974 Light Truck Service Manual is applicable to 1976 Light Trucks. M AINTENANCE ITEM K-MODEL CV JO INT LUBRICATION RING GEAR SIZE SOURCE TYPE /C A PA C ITY C10 C hevrolet S a lis b u ry /3 7 5 0 # 8 - 7 /8 " K10 C hevrolet S a lis b u r y /3 7 5 0 # 8 - 7 /8 " K10 C hevrolet S a lis b u r y /4 0 0 0 # 8 - 7 /8 " P10 C h evrolet S a lis b u r y /3 5 0 0 # 8 - 7 /8 " G10 C hevrolet S a lis b u r y /3 1 0 0 # 8 - 7 /8 " G10 C hevrolet S a lis b u ry /3 1 0 0 # 8 - 1 /2 " MODEL C20 (Except Crew Cab) C hevrolet S a lis b u r y /5 7 0 0 # 1 0 -1 /2 " C20 (Crew Cab) C hevrolet S a lis b u r y /7 5 0 0 # 1 0 -1 /2 " K20 C h evrolet S a lis b u ry /5 7 0 0 # 1 0 -1 /2 ” P20 C hevrolet S a lis b u r y /5 7 0 0 # 1 0 -1 /2 " G20 C hevrolet S a lis b u ry /3 5 0 0 # 8 - 7 /8 " C30 (Except Dual Wheel Camper) C hevrolet S a lis b u r y /7 5 0 0 # 1 0 -1 /2 " C30 (Dual Wheel Camper) Dana S a lis b u r y /7 5 0 0 # 1 0 -1 /2 " C h evrolet S a lis b u r y /7 9 0 0 # 1 0 -1 /2 " C hevrolet B a n jo /1 1 ,0 0 0 # 1 2 -1 /4 " C hevrolet S a lis b u ry /'5 7 0 0 # 1 0 -1 /2 " Dana S a lis b u r y /6 2 0 0 # 9 - 3 /4 " Dana S a lis b u r y /7 5 0 0 # 1 0 -1 /2 " P30 P30 (With H 22/H 23) G30 _ ,n G30 r _n G30 (Dual Wheel) (Dual Wheel) Fig. 1--Axle C h a rt Propshaft CV joints can be lubricated while "on-the-vehicle", with the use of J-25512-1 and adaptor J-25512-2. Access to the joint is limited and can best be accomplished by the following procedure. Figure 2 shows how the joint conceals the lube fitting (A) when it is in the downward position; and how it opens (B) when the fitting is in the upward position. Access to the lube fitting can only be gained from above the opened joint. This require a flex-hose that can bend between the propshaft and the underbody. Install the rigid needle tip, J-25512-2, on the end of the flexhose. Use the tip to depress the ball into the lube fitting, then pump grease into the fitting as shown in figure 3. CLOSED POSITION OPEN POSITION Fig. 2--C lo s ed and O p en P osition s TR U C K SUPP - S E R VIC E 4-2 REAR SUSPENSION, PROPSHAFT A ND A XLE PROPSHAFT Universal Joint-Repair Two methods of retaining trunnions to universal joint yokes may be used. Each requires a different repair procedure. The snap ring method is described on pages 4-9 through 4-10 of the 1974 Light Duty Truck Service Manual. An injection-molded plastic retainer ring is used on other universal joints. For this type joint, the following repair procedure should be used. Disassembly NOTE: Never clamp propshaft tube in a vise as the tube may be dented. Always clamp on one of the yokes, and support the shaft horizontally. Avoid damaging the slip yoke sealing surface. Nicks may damage the bushing or cut the seal lip. REAR SPRING U-BOLT Rear spring U-bolt and anchor plate installation must be as shown in figure 4. BUSHING REPLACEMENT- Rear Spring, Front Eye Heavy duty leaf springs on C20 and C30 trucks use a staked-in-place front eye bushing. Before this bushing is pressed out of the spring, the staked locations must be straightened with a chisel or drift. A fter a new bushing is installed, it must be staked in three equally spaced locations. Refer to page 4-6 in the 1974 Light Duty Truck Service Manual. 1. Support the propshaft in a horizontal position in line with the base plate of a press. Place the universal joint so that the lower ear of the shaft yoke is supported on a 1-1/8" socket. Place the cross press, J-9522-3, on the open horizontal bearing cups, and press the lower bearing cup out of the yoke ear as shown in figure 5. This will shear the plastic retaining the lower bearing cup. 2. If the bearing cup is not completely removed, lift the cross and insert Spacer J-9522-5 between the seal and bearing cup being removed, as shown in figure 6. Complete the removal of the bearing cup, by pressing it out of the yoke. 3. R otate the propshaft, shear the opposite plastic retainer, and press the opposite bearing cup out of the yoke as before, using Spacer J-9522. NOTE: " U " BOLTS MUST BE LOCATED ARO UND THE A X LE TUBE SO TH A T THE LEGS PASS THE SPRING SEAT _______ W ITHIN .060._______________________ Fig. 4 - U - B o lt In s ta lla tio n Fig. 5--P ressin g O u t B earin g C up T R U C K SUPP - SER VICE REAR SUSPENSION, PROPSHAFT A ND A X L E 4-3 TRUNNION 'SPACER J-9522-5 .BEARING CUP Fig. 6--U sin g S p a c e r to R em ove B e a rin g C up Fig. 8 --In s ta llin g T ru n n io n in to Y o ke 4. Disengage cross from yoke and remove. NOTE: Production universal joints cannot be reassembled. There are no bearing retainer grooves in production bearing cups. Discard all universal joint parts removed. 5. Remove the remains of the sheared plastic bearing retainer from the ears of the yoke. This will aid in reassembly of the service joint bearing cups. It usually is easier to remove plastic if a small pin or punch is first driven through the injection holes. 6. If the front universal joint is being serviced, remove the pair of bearing cups from the slip yoke in the same manner. Reassem bly A universal joint service kit is used when reassembling this joint. See figure 7. This kit includes one pregreased cross assembly, four service bearing cup assemblies with seals, needle rollers, washers, grease and four bearing retainers. M ake sure that the seals are in place on the service bearing cups to hold the needle rollers in place for handling. 1. Remove all of the remains of the sheared plastic bearing retainers from the grooves in the yokes. The sheared plastic may prevent the bearing cups from being pressed into place, and this could prevent the bearing retainers from being properly seated. 2. Install one bearing cup part way into one side of the yoke, and turn this yoke ear to the bottom. 3. Insert cross into yoke so that the trunnion seats freely into bearing cup as shown in figure 8. 4. Install opposite bearing cup part way. Make sure that both trunnions are started straight and true into both bearing cups. 5. Press against opposite bearing cups, working the cross all of the time to check for free movement of the trunnions in the bearings. If there seems to be a hang-up, stop pressing and recheck needle rollers, to determine if one or more of them has been tipped under the end of the trunnion. 6. As soon as one bearing retainer groove clears the inside of the yoke, stop pressing and snap the bearing retainer into place as shown in figure 9. ROLLER BEARINGS BEARING RETAINER BEARING CUP FLAT PLASTIC WASHER ROUND PLASTIC WASHER Fig. 7 --R e p a ir K it Fig. 9 —In s ta llin g S n a p Ring to R etain T ru n n io n TRUC K S UPP - S E R V IC E 4-4 REAR SUSPENSION, PROPSHAFT A ND A XLE ALIGNMENT STRIKE TUBE YOKE EAR IN THIS AREA Fig. 1 1 -A lig n m e n t Key PROPSHAFT INSTALLATIO NCORRECT PHASING Fig. 1 0 --S e a tin g S n a p Rings 7. Continue to press until the opposite bearing retainer can be snapped into place. If difficulty is encountered, strike the yoke firmly with a ham m er to aid in seating bearing retainers. This springs the yoke ears slightly. See figure 10. 8. Assemble the other half of the universal joint in the same manner. 9. Check the freedom of the rotation of both sets of trunnions of the cross. If too tight, again rap the yoke ears as described above. This will loosen the bearings and help seat the bearing retainers. © When reinstalling propshafts, it is necessary to place the shafts into particular positions to assure proper operation. This is called phasing. Refer to procedures and illustrations on page 4-12 o f the 1974 Light Duty Truck Service Manual. For 1976 trucks, three m ethods of phasing are used. All models w ith 32 splines use an alignment key, as shown in figure 11, to obtain proper phasing. The shafts can mate only in the correct position. C and G models w ith 16 splines must be phased as shown in figure 12. The rear shaft m ust be rotated four splines-90°toward the left side of the vehicle after aligning the trunnions vertically, as shown. K models w ith 16 splines must align the trunnions vertically before installing. Do not rotate the shafts. PLACE FRONT YOKE OF REAR PROP SHAFT IN VER TIC A L POSITION © 1 ) PLACE TRANSMISSION SLEEVE YOKE IN VE R TIC A L POSITION REAR PROP SHAFT ROTATE REAR SHAFT 4 SPLINES (90°) TOWARD L.H. SIDE INSTALL REAR SHAFT TO FRONT SHAFT Fig. 1 2 -A lig n m e n t fo r P hasing - C and G M o d e ls O n ly TRUC K SUPP - S ER VICE REAR SUSPENSION, PROPSHAFT A N D A X L E 4-5 Fig. 13 ~ R e m o vin g Lock S c re w AXLE SHAFT Remove and Reinstall Axles equipped with 8-7/8" ring gears and Eaton Locking differentials use a thrust block on the pinion shaft which affects the removal of axle shafts as noted below. 1. Raise the vehicle on a hoist. Remove both rear wheel and tire assemblies and both rear brake drums. 2. Remove the rear cover and drain the lubricant. 3. Rotate the case to the position shown in figure 13. Support the pinion shaft so that it cannot fall into the case, then remove the lock screw. 4. Carefully withdraw the pinion shaft part-way out, as shown in figure 14. R otate the case until the shaft touches the housing. Fig. 1 4 --P o s itio n in g C ase For B est C le a ra n c e 5. Reach into the case with a screwdriver or similar tool, and rotate the C-lock until its open end points directly inward, as shown in figure 15. The axle shaft cannot be pushed inward until the C-lock is properly positioned. Do not force or hammer the axle shaft in an attem pt to gain clearance. 6. W hen the C-lock is positioned to pass through the end of the thrust block, push the axle shaft inward as shown in figure 16, and remove the C-lock. Remove the axle shaft and repeat steps 5 and 6 for the opposite axle shaft. 7. When installing C-locks keep the pinion shaft partially withdrawn. Place the C-lock in the same position shown in figure 15. Carefully w ithdraw the axle shaft until the C-lock is clear of the thrust block. W hen both locks are installed, install the pinion shaft and lock screw. Fig. 16~P u sh A xle S h a ft In w a rd TRUC K SUP P - S E R VIC E S E C TIO N 5 BRAKES The following caution applies to one or more steps in the assembly procedure of components in this portion of the manual as indicated at appropriate locations by the terminology "See Caution on page 1 of this section". C A U T I O N : THIS FASTENER IS A N IMPORTANT A TTACHING PART IN THAT IT COULD AFFECT THE PERFORMANCE OF VITAL COMPONENTS AN D SYSTEMS, AND/OR COULD RESULT IN MAJOR REPAIR EXPENSE. IT MUST BE REPLACED WITH ONE OF THE SAME PART NUMBER OR WITH A N EQUIVALENT PART IF REPLACEMENT BECOMES NECESSARY. DO NOT USE A REPLACEMENT PART OF LESSER QUALITY OR SUBSTITUTE DESIGN TORQUE VALUES MUST BE USED AS SPECIFIED DURING REASSEMBL Y TO ASSURE PROPER RETENTION OF THIS PART C O N T E N T S OF T H IS S E C T IO N Brake System Identification.............................................................. 5-1 Standard B rakes................................................................................... ..5-5 Vacuum Power Brakes.........................................................................5-10 Hydro-boost B rakes............................................................................ ..5-10 BRAKE SYSTEM IDENTIFICATION The following charts are included as a guide in determining vehicle brake system. The first chart describes brake systems and their basic differences. The remaining charts outline system to vehicle application. BRAKE SYSTEM DESCRIPTION SYSTEM FR O N T B RAKES R EAR BR A K ES B R A K E ASSIST JB1 Disc 11.86 x 1.28 Drum 11.00 x 2.00 None (Manual Brakes) JB3 Disc 11.86 x 1.28 Drum 11.00 x 2.00 Vacuum - Single Diaphragm JB5 Disc 11.86 x 1.28 Drum 11.00 x 2.75 Vacuum - Dual Diaphragm JB6 Disc 12.50 x 1.28 D rum 11.15 x 2.75 Vacuum - Dual Diaphragm JB7 Disc 12.50 x 1.28 D rum 13.00 x 2.50 Vacuum - Dual Diaphragm JB8 Disc 12.50 x 1.53 D rum 13.00 x 3.50 H yd ra u lic - H yd ro bo ost JB9 Disc 14.25 x 1.53 D rum 15.00 x 4 .0 0 H yd ra u lic - H yd ro b o o st TRUC K S UPP - SER VIC E 5-2 BRAKES BRAKE SYSTEM APPLICATION MODEL TON RATING C10516 1/2 C10703 106.5 117.5 C10903 3 /4 C20906 C30943 JB5 Base JB1 JB3 JB5 4900 5300-5600 5300-6200 Base J50 J55 JB1 JB3 JB5 129.5 6050-7000 Base JB5 131.5 6400-7100 6400-8200 Base J55 JB6 JB7 7100 7100-8200 Base J55 JB6 JB7 7500-8200 Base JB7 8200 Base JB7 164.5 1 Base J50 J55 C20963 C30903 6050-6200 4900 129.5 C20943 GVW RATING BRAKE SYSTEM 5300-5600 5300-6200 131.5 C10906 C20903 WHEELBASE M ERCH ANDIZING OPTION 131.5 6600-8200 6600-10000 Base J55 JB7 JB8 164.5 9000-10000 Base JB8 9000-10000 Base JB8 C30963 C31003 135.5 6600-8200 6600-10000 Base J55 JB7 JB8 C31403 159.5 6600-8200 6600-10000 Base J55 JB7 JB8 TR U C K S U P P ■ SER VIC E BRAKES 5-3 BRAKE SYSTEM APPLICATION (continued) M ERC H A N D IZIN G MODEL TON RATING K10516 1/2 BRAKE GVW RATING OPTION SYSTEM 106.5 6200-6300 Base JB5 K 10703 117.5 6200-6400 Base JB5 K 10903 131.5 6200-6400 Base JB5 K 10906 129.5 6200-7300 Base JB5 131.5 6800 6800-8400 Base J55 JB6 JB7 129.5 6800 6800-8400 Base J55 JB6 JB7 K20903 3/4 K20906 WHEELBASE 4800 4800-5600 Base JB1 J50 JB3 5400-5600 Base JB3 4900 4900-5600 Base J50 JB1 JB3 5600 Base JB3 6400 Base JB5 6400 Base JB5 6400 Base JB5 6400 Base JB5 110 6400-7100 6400-8100 Base J55 JB6 JB7 125 6600-7400 6600-8400 Base J55 JB6 JB7 G31306 6600-7400 6600-8400 Base J55 JB6 JB7 G31303 6400-8400 8900 Base JB7 J55 JB8 8900-10000 Base JB8 G11005 1/2 110 G11006 125 G11305 G11306 G21005 3/4 110 G21006 125 G21305 G21306 G31005 G31305 G 31603 1 146 TRUC K SUPP - S E R V IC E 5-4 BRAKES BRAKE SYSTEM APPLICATION (continued) BRAKE MODEL TON RATING WHEELBASE GVW RATING M ERCH ANDIZING OPTION P10542 1/2 102 6200 Base JB5 P20842 3/4 125 6800 Base 6800-8000 J55 JB6 JB7 133 6800 6800-8000 Base J55 JB6 JB7 125 7600-8200 7600-10000 12000-14000 Base J55 H22 or H23 JB7 JB8 JB9 7600-12500 Base JB8 P21042 P30842 1 P30832 SYSTEM P31042 133 7600-8200 7600-10000 12000-14000 Base J55 H22 or H23 JB7 JB8 JB9 P31132 137 7600-12500 Base JB8 P31432 158.5 7600-12500 14000 Base HF7 or HF8 JB8 Base J55 H22 or H23 JB7 JB8 JB9 Base JB9 P31442 157 P31832 I78 7600-8200 7600-10000 12000-14000 14000 JB9 T R U C K SUP P - S ER VIC E BRAKES 5-5 STANDARD BRAKES The 1976 Light Duty Truck standard brake components are essentially the same as those described in the 1974 Light D uty Truck Service Manual. Design modifications, differing from the 1974 manual, are outlined on the following pages. FRONT DISC BRAKE PARKING BRAKE F ront disc brake rotors do not incorporate an anti-squeal groove in the disc pad contact surfaces (fig. 1). Parking brake and cable replacement procedures remain the same as described in the 1974 Light Duty Truck Service Manual; however, cable routings, clips or guides incorporate minor changes as noted in Figures 3 thru 5. BRAKE PEDAL ADJUSTM ENT All brake pedal push rods are non-adjustable on 1976 models except M otor Home Chassis Units - see the Hydro-boost section of the 1974 Service M anual. STOPLAMP SW ITCH INSTALLATION (C-K Models) The stoplam p switch is mounted to a flange protruding from brake pedal support bracket. Installation (Fig. 2) 1. Install the mounting clip in the brake pedal flange from the pedal side of the flange. 2. Depress the brake pedal and push the switch into the clip until the shoulder on the switch bottoms on the clip. Adjustm ent PARKING BRAKE ADJUSTM ENT Prestretch Requirement (All Vehicles) If a new parking brake cable has been installed in the vehicle, it should be prestretched prior to adjustment. W ith the equalizer installed, apply the parking brake with heavy force and release three times. Adjustment - Foot Pedal Type NOTE: Before adjusting parking brake, check service brake condition and adjustment. 1. Raise vehicle on a hoist. 2. Loosen the equalizer adjusting nut. 3. Apply the parking brake 4 notches from the fully released position. 1. Pull the brake pedal back against switch with 15-20 lbs. force to properly adjust switch. 4. Tighten the equalizer adjusting nut until a moderate drag is felt when the rear wheels are rotated forward. 2. Electrical contact should be made when the brake pedal is depressed 1.00" to 1.24" from its normally released position. CAUTION: See "Caution " on page 1 o f this section. 5. Fully release the parking brake and rotate the rear wheels. No drag should be present. NEW Fig. 1--Disc B ra ke R otor TRUC K SUP P - SER VIC E 5-6 BRAKES C -K M O D E L S P 0 0 0 (4 2 ) MODELS G MODELS P 3 0 0 (3 2 ) MODELS 1^1LW W Fig. 3--P a rk in g B ra ke A s s e m b ly -T y p ic a l 6. Remove vehicle from hoist. Adjustm ent - Orsheln Type Refer to the 1974 Light D uty Truck Service M anual, page 5-23. Adjustment - (Propshaft) Internal Expanding Drum On adjustment until shoes are tight against drum and drum cannot be rotated by hand. Back off adjustment ten notches and check drum for free rotation. 5. Place parking brake lever in fully released position. Take up slack in brake linkage by pulling back on cable just enough to overcome spring tension. Adjust clevis of pull rod or front cable to line up with hole in relay levers. 1. Jack up at least one rear wheel. Block wheels and release hand brake. a. Insert clevis pin and cotter pin, then tighten clevis locknut. 2. Remove cotter pin and clevis pin connecting pull rod and relay lever. This will assure freedom for full shoe release. b. Install a new metal hole cover in drum to prevent contam ination of brake. C A U T I O N : It may be necessary to knock out lanced area in brake drum with punch and hammer to gain entry into adjusting screw through brake drum. Be sure all metal has been removed from parking brake compartment. 3. Rotate brake drum to bring one of access holes into line with adjusting screw at bottom of shoes (manual transmission), top of shoes (automatic transmission). 4. Expand shoes by rotating adjusting screws with screwdriver inserted through hole in drum. Move outer end of screwdriver away from drive shaft. Continue c. Lower rear wheels. Remove jack and wheel blocks. CAUTION: See "Caution " on Page 1 o f this section. PARKING BRAKE (PROPELLER SHAFT)INTERNAL EXPANDING Removal 1. Remove the propeller shaft; see Section 4 of the 1974 Light D uty Truck Service M anual. 2. Remove the brake drum. NOTE: It may be necessary to back off the shoe adjustment before removing the drum. TR U C K SUP P - S ER VIC E BRAKES 5-7 Fig. 4 - P a r k i n g B ra ke Syst em (Typ ic al) TR U C K S UPP - SER VIC E 5-8 BRAKES P 314 (3 2 ) & JB9; P 318 (3 2) P 300 (4 2 ) & M 4 0 & JB9 Fig. 5- -P ar kin g B ra ke Syst em (Prop sha ft) TR U C K SUP P • SER VIC E BRAKES 5-9 On autom atic transmission models, the exhaust crossover pipe may be in the way. If so, loosen the transmission rear mounting bolts and jack the transmission sufficiently for brake drum to clear the pipe. 3. Remove the two pull back springs. 4. Remove the guide plate from anchor pin. 5. Remove shoe hold down cups, springs, and washers from hold down pins-rem ove pins. 3. Install cable assembly from back of flange plate. Push retainer through hole in flange plate until tangs securely grip the inner side of the plate. 4. Place washer and reinforcement over the threaded end of anchor pin. Hold anchor pin nut (flat side against flange on flange plate) in position behind flange plate and insert threaded end of anchor pin from front side. Thread the anchor pin into nut and tighten securely (140 foot pounds torque). Bend tang of washer over reinforcement and side of washer over hex of anchor pin. 6. Pull brake shoe and lining assemblies away from anchor pin and remove the strut and spring. CAUTION: See "Caution " on Page 1 of this section. 7. Lift the brake shoes and linings with the adjusting nut and bolt and connecting spring off the flange plate. 5. Install lever on cable by compressing spring and inserting cable in channel of lever. Release spring. 8. Move the shoes toward each other until the adjusting bolt and connecting spring drop off. 6. Install prim ary shoe (short lining) to lever as follows: Place pin in lever, place washer on pin and push pin through hole in prim ary shoe. Fasten parts together by installing the clip in groove of pin. 9. Remove the clip holding the brake lever to the primary shoe (shoe with short lining). 10. Compress the spring on the brake cable and remove the cable from the lever. 11. If necessary to remove the anchor pin, straighten the washer from pin hex and reinforcement. Remove reinforcement and washer with anchor pin. 12. If necessary to remove the cable, compress tangs on cable and pull assembly out of the hole in the flange plate. 13. If necessary to remove the flange plate, remove the transmission flange nut and transmission output flange. Remove bolts holding the flange plate to bearing retainer and remove the flange plate. Inspection Replace any worn or broken parts. Installation 1. Place the flange plate in position on the rear bearing retainer and fasten with four bolts. Torque bolts to 24 foot pounds. CAUTION: See "Caution " on Page 1 o f this section. 2. Install transmission output flange on spline of mainshaft and fasten with flange nut. Torque nut to 100 foot pounds. CAUTION: See "Caution "on Page 1 o f this section. CAUTION: See "Caution " on Page 1 of this section. 7. Fasten two brake shoes and linings together by installing connecting spring. Move the shoes toward each other and install adjusting screw. 8. Lubricate the flange plate contact surfaces with a very light coat of Delco Brake Lube #5450032 (or equivalent). 9. Place shoe and linings in position on flange plate. NOTE: W hen facing the brake assembly, the shoe with the short lining should be to the left with the lever assembled to it (automatic transmission, to the right (manual transmission). 10. Pull brake shoes apart and install strut lever and spring between them. The loop on the strut spring should be in the "up" position. 11. Install hold down pins, washers, springs and cups from flange plate to shoes. 12. Place guide plate on anchor pin. 13. Install pull back springs. 14. Remove the "knock out" plug (if necessary) and install a new metal plug in the brake drum adjusting hole. 15. Install the brake drum. 16. Install the propeller shaft. TR U C K SUPP - SER VIC E 5-10 BRAKES VACUUM POWER BRAKES POWER BOOSTER - REPAIR OR REPLACE CAUTION: Any time the power brake vacuum booster is removed for repair or replacement, be sure to install a N E W check valve. HYDRO-BOOST POWER BRAKES All 1976 hydro-boost vehicles will incorporate an accum ulator which is integral with the booster (fig. 6). INTEGRAL ACCUMULATOR/BOOSTER W A R N I N G : Do not attem pt to disassemble or cut into the accumulator. The accumulator contains a spring compressed under high pressure. The booster power section includes three ports (fig. 6): 1. Pressure Port (11/16-18 th re a d )-th e high pressure line from the power steering pump is connected to this port. 2. G ear Port (5/8-18 th re a d )-th e high pressure line leading to the power steering gear is connected to this port. 3. Return Port (for 3/8 I.D. H ose)-the return line to the power steering pum p is connected to this port. The pressure port and the gear port each contains an aluminum tube seat insert. The accum ulator valve components are assembled in the accum ulator valve bore which is machined in the housing. This bore is connected by passages to the accum ulator and to the pressure port. The integral spring accum ulator (fig. 7) is used in conjunction with the hydraulic brake booster. The accum ulator piston assembly and spring are assembled in the accum ulator bore which is machined in the housing. BLEEDING HYDRO-BOOST/POW ER STEERING HYDRAULIC SYSTEM The following procedure should be used to bleed the power steering hydraulic system on hydro-boost vehicles. NOTE: If the power steering fluid has foamed due to low fluid level, it will be necessary to park the vehicle for approximately one hour (reservoir cap loose) so that the foam can dissipate. 1. Raise the front of the vehicle on a hoist so that the tires are clear of the floor. 2. Check reservoir and fill with G M Power Steering Fluid (or equivalent). NOTE: Leave the reservoir cap off during entire bleed procedure. PRESSURE PORT Fig. 6 --H y d ro -B o o s t W ith In te g ra l A c c u m u la to r T R U C K S U P P - SER VIC E BRAKES 5-11 3. Install a remote control starter switch so that engine can be cranked but not started. CAUTION: Whenever the engine is cranked remotely at the starter, with a specialjumper or other means, the distributor primary lead must be disconnected from the negative post on the coil. 4. C rank engine for 4 to 5 second intervals while pouring fluid into the reservoir. 5. Fill reservoir and crank as in step 4 until system will no longer accept fluid. It is norm al that fluid may spill when cranking stops (it is the result of air in the system trying to escape). To prevent spilling, crank engine. 6. Remove remote control distributor primary lead. starter switch. Reinstall 7. Start engine and allow to run 2 seconds. 8. Check and refill fluid reservoir if necessary. 9. Start engine and depress the brake pedal several times while rotating the steering wheel from stop to stop. 10. T urn engine off and then pump brake pedal 4-5 times to deplete accum ulator pressure. 11. Check and refill fluid reservoir if necessary. 12. Repeat Steps 9, 10 and 11. Install pum p reservoir cap. 13. Remove vehicle from hoist. BRAKE PEDAL ADJUSTM ENT All hydro-boost equipped vehicles incorporate non-adjustable brake pedal rods except P30(32) models. Refer to the 1974 Light D uty T ruck Service M anual for brake pedal adjustm ent on P30(32) models. BOOSTER INSTALLATION Refer to Figure 8 for booster installation. HYDRAULIC LINE ROUTING Refer to Figures 9 thru 11 for typical hydraulic line routings. M in i-M a s te r Cylinder 1976 G Series trucks (with H ydroboost) and all P Series trucks will incorporate new Bendix mini-master cylinders (fig. 12). Due to the new size, the G series master cylinder is mounted straight out from the dash rather than laterally in the vehicle as in 1975 (fig. 8). Replacement procedures remain basically unchanged to those described in the 1974 Truck Service Manual. On four-wheel disc brake vehicles (JF9), the brake warning light switch (fig. 6) is an integral part of the mini-master cylinder assembly; it is non-serviceable. A brake line distribution block is located on the frame crossmember. It is not a combination valve; its only function is to act as a distributor for attaching front and rear brake lines. actuator of the prim ary piston are in contact with the compensating valve stems which project into the cylinder bore. This keeps the valves off of their seat and opens communication between the cylinder bore and the reservoir. The initial forward movement of the pistons permits the compensating valves to seat which closes communication between the pressure chambers in the cylinder bore and the reservoirs. Any further movement of the pistons builds up pressure which is transm itted to the calipers or wheel cylinders. Disassembly 1. Remove the reservoir cover and diaphragm, and drain the fluid from the reservoir. 2. Remove the four bolts that secure the body to the reservoir using Socket J-25085. 3. Remove the small "O" ring and the two compensating valve seals from the recessed areas on the bottom side of the reservoir. NOTE: Do not remove the two small filters from the inside of the reservoir unless they are damaged and are to be replaced. 4. Depress the prim ary piston using a tool with a smooth rounded end. Then remove the compensating valve poppets and the compensating valve springs from the compensating valve ports in the master cylinder body WARNING: It air pressure is used to remove the secondary piston, place the open end of the cylinder bore approximately 1" from a padded workbench or other surface to catch the piston when it comes out of the bore. Apply low air pressure very carefully to ease the piston out of the bore. Never point the open end of the bore at anyone when applying air pressure. The piston may come out of the bore with considerable force and cause personal injury. 5. Using a small screwdriver, remove the snap ring at the end of the m aster cylinder bore. Then release the piston and remove the primary and secondary piston assemblies from the cylinder bore. It may be necessary to plug the front outlet port and to apply low air pressure to the front compensating valve port to remove the secondary piston assembly. Cleaning and Inspection The com ponent parts of the mini-master cylinder differ from those of a conventional master cylinder although their functions are essentially the same. A disassembled master cylinder is shown in Figure 13. Wash all parts to be re-used in clean brake fluid. Be sure that all foreign m atter is removed from the filters in the bottom of the reservoir. If the filters do not clean up, they must be replaced. Note that when the m aster cylinder is in the released position (fig. 14), the actuator of the secondary piston and the After cleaning, inspect the parts for damage and excessive wear, and replace as required. TR U C K SUPP - S E R VIC E 5-12 BRAKES P MODELS (EXCEPT M O TO R H O M E ) M O TO R HO M E CHASSIS MODELS Fig. 8 --H y d ro -B o o s t In s ta lla tio n Assembly 1. Lubricate the secondary piston assembly and the master cylinder bore with clean brake fluid. 2. Assemble the secondary spring (shorter of the two springs) in the open end of the secondary piston actuator, and assemble the piston return spring (longer spring) on the projection at the rear of the secondary piston. 3. Insert the secondary piston assembly, actuator end first, into the master cylinder bore, and press assembly to the bottom of the bore. 4. Lubricate the prim ary piston assembly with clean brake fluid. Insert the prim ary piston assembly, actuator end first, into the bore. 5. Place the snap ring over a smooth round ended tool and depress the pistons in the bore. 6. Assemble the retaining ring in the groove in the cylinder bore. 7. Assemble the compensating valve seals and the small "O" ring seal in the recesses on the bottom of the reservoir. Be sure that all seals are fully seated. 8. While holding the pistons depressed, assemble the compensating valve springs and the compensating valve poppets in the compensating valve ports. 9. Holding the pistons compressed, position the reservoir on the master cylinder body and secure with the four m ounting bolts. Tighten the bolts to 12-15 ft. lbs. Bench Bleeding 1. Plug the outlet ports and fasten the master cylinder in a vise with the front end tilted slightly down. 2. Fill the reservoir with clean brake fluid. Use any tool with a smooth rounded end to depress and release the TR U C K S UPP - SER VIC E BRAKES 5 -1 3 Fig. 9 ~ P o w e r S te e rin g Hose Routing - C M o d e l s TRUC K SUP P - S E R V IC E 5 -1 4 BRAKES Fig. 10 --P o w e r S te e rin g Hose Routing - G M o d e l s TR U C K SUPP - SER VIC E BRAKES 5-15 Fig. 1 1--Pow er S te e rin g Hose Rou tin g - P M o d e l s TR U C K SUPP - S E R VIC E 5 -1 6 BRAKES primary piston several times. 3. Reposition the master cylinder in the vise with the front end tilted slightly up. Again, depress and release the primary piston several times. 4. Assemble the diaphragm and cover on the master cylinder. NOTE: The master cylinder is ready for installation on the vehicle. N orm al bleeding procedures should be followed after the m aster cylinder is installed. Fig. 1 2 ~ B e n d ix M in i-M a s te r C y lin d e r Fig. 13 --M in i-M a s te r C y lin d e r - E xploded V ie w T R U C K SUP P - SER VIC E BRAKES 5 -17 Fig. 1 4 --M a s te r C y lin d e r In R ele ased P osition TRUC K SUP P - S E R V IC E 5 -1 8 BRAKES D IA G N O SIS - HYDRO - BOOST SYSTEM N O T E: B efore checking the hydraulic p o w e r booster for the source o f trouble, refer to the trouble diagnosis procedures fo r Standard Brakes. A fte r these possible causes have been elim inated, ch eck fo r the probable cause and rem edy as o u tlin ed below: Normal Operating Characteristics Brake pedal application o f the H ydro-boost system differs in som e respects from a vacuum ty p e pow er brake system in the follow ing m anner: 1. On pedal application until booster run-out, slight pow er steering pum p noise m ay be heard. 2. Pedal application through run-out will n o t necessarily be sm ooth due to the internal ratio change. It is possible to push the pedal past run-out because o f the higher pedal ratio. A t run-out o f the vacuum booster the pedal ju st becom es hard. 3. On the first full application o f the brake pedal, a slight hissing sound m ay be heard. The hiss is the accum ulator charging and the noise should go away in a sh o rt period o f tim e. 4. On a spike brake application, a slight pedal kick-back m ay be felt. 5. If the vehicle is sta rted w ith the pedal de­ pressed, the pedal will fall away slightly then return back to approxim ately the original position. N O B O O S T - H A R D PEDAL Preliminary Check W ith the engine stopped, depress the brake pedal several tim es to e lim inate all accum ulato r reserve fro m the system. Hold the brake pedal depressed w ith m edium pressure (25 to 35 lbs.), start the engine. If the u n it is operating c o rre c tly , the brake pedal w ill fall s lig h tly and then push back against the driver's fo o t, rem aining at abo ut the same po s itio n . If the booster is not operating c o rre c tly , the tro u b le may be one o f the fo llo w in g causes: P r o b a b le C a u s e Remedy 1. Loose or broken power ste e rin g pump belt. 1. Tighten or replace the b elt. 2. No f l u i d in power s te e rin g r e s e r v o i r . 2. F i l l r e s e r v o i r and check f o r external le aks. 3. Leaks in power s t e e rin g , booster or accumulator hoses. 3. Replace d efe ctive p arts. 4. Leaks a t tube f i t t i n g s , power s te e rin g , booster or accumulator co nnettions. 4. Tighten f i t t i n g s or replace tube se ats, i f d efe ctive. 5. External leakage at accumulator. 5. Replace booster. 6. Faulty booster p is t o n seal causing leakage a t booster flan g e vent. 6. Replace a l l booster s e a l s . 7. Faulty booster input rod seal with leakage at input rod end. 7. Replace a l l booster s e a l s . 8. Faulty booster cover seal with leakage between housing and cover. 8. Replace a l l booster s e a l s . 9. Faulty booster spool plug seal. 9. Replace a l l booster s e a l s . 10. 11 . 12. In ternal leakage in booster. 10. Replace booster. Contamination in power s te e r in g f l u i d . 11. Flu sh power ste e rin g system and repla ce with new f l u i d . Hydraulic l i n e s routed i n c o r r e c t ly . 12. Re-route l i n e s . T R U C K SUP P - S E R VIC E BRAKES 5-19 D IA G N O SIS - HYDRO - BOOST SYSTEM S L O W BRAKE PEDAL RETURN Remedy P r o b a b le C a u s e 1. Exc e ssive seal f r i c t i o n in booster. 1. Replace a l l booster s e a ls. Clean spool and repla ce a l l booster s e a l s . 2. Faulty spool a ctio n. 2. 3. Broken p iston return s p r in g . 3. Replace s p r in g . 4. R e s t r i c t i o n in return l i n e from booster to pump r e s e r v o i r . 4. Replace li n e . 5. Broken spool return s p r in g . 5. Replace s p r in g . 6. Exc e ssive pedal p iv o t f r i c t i o n . 6. Lubricate p iv o t bushings with Delco Brake Lube #5450032 (or equivalent) or replace bushi n g s . G R A B B Y BRAKES Remedy P r o b a b le C aus e 1. Broken spool return s p r in g . 1. Replace s p r in g . 2. F aulty spool a ctio n caused by contamination in system. 2. In spect, clean and replace a l l booster s e a l s . 3. No cargo body on c h a s s i s . 3. Normal c o n ditio n . BOOSTER CHATTERS - PEDAL VIB RA TES Remedy P r o b a b le C a u s e 1. Power ste e rin g pump b e l t s l i p s . 1. Tighten bel t. 2. Low f l u i d level in power s te e rin g pump r e s e r v o i r . 2. F i l l r e s e r v o i r and check fo r external le a k s. 3. Fau lty spool operation caused by contamination in system. 3. In spect, clean and replace a l l booster s e a l s . 4. Ex cessive contamination in power ste e rin g f l u i d . 4. Flush power ste e rin g f l u i d from system and replace with new power s te e rin g f l u i d . 5. A i r in power ste e rin g f l u i d . 5. Allow v e h icle to stand fo r approximately one hour; then bleed power ste e rin g h y d ra u lic system as described e a r l i e r in t h i s s e ctio n. TR U C K SUPP - S E R VIC E 5 -2 0 BRAKES D IA G N O SIS - HYDRO-BOOST SYSTEM P O W E R STEERING P U M P N O IS E O N BRAKE A PP LY Remedy P r o b a b le C a u s e 1. I n s u f f i c i e n t f l u i d in pump reservoi r . F lu id level decreases approximately 1/2" on brake a p p l ^ - r e f i 11 to proper le v e l. I f f l u i d i s foamy, l e t v e h icle stand f o r approximately one hour; then bleed power ste e rin g h yd ra u lic system as o u tlin e d e a r l i e r in t h i s se ctio n. BRAKE PEDAL PULLS D O W N SLIG H TLY O N E N G IN E START P r o b a b le C a u s e 1. Remedy R e s t r ic t i o n in gear or booster return l i n e s . 1. Replace li n e s or re p o s i t i o n li n e s to eliminate r e s t r i c t i o n . A C C U M U L A T O R L E A K D O W N - S YS TEM D O ES N O T H O L D C H A R G E Prelim inary Check Start engine and tu rn the steering wheel u n til the wheels contact the wheel stops lig h tly . Hold f o r a m axim um of five seconds. Then release the steering wheel and tu rn o ff the engine. Depress and release the brake pedal. There should be a m in im u m o f three power assisted brake app lica tions before a hard pedal is obtained. Re-start the engine and turn the steering wheel u n til the wheels contact the wheel stops lig h tly . There should be a lig h t hissing sound as the accum ulator is charged. Hold steering wheel lig h tly against stop fo r a m axim um of five seconds. Then release the steering wheel, and tu rn o ff the engine. Wait one hou r and apply brake pedal (do not re-start the engine). There should s till be a m in im u m of three pow er assisted brake applications before obtaining a hard pedal. If eithe r o f these pre lim in a ry checks shows th a t the accum ulato r is not holdin g its charge, the tro u b le may be one of the fo llo w in g causes. P r o b a b le C a u s e R em edy 1. External leakage at accumulator welds. 1. Replace booster assembly. 2. Internal leakage in accumulator (p ast p iston seal or r e l i e f valve ). 2. Replace booster. 3. 3. Internal leakage a t booster accumulator valve ( i f accumulator is not le aking e x te r n a lly or i n t e r n a l l y ) . Replace a l l booster se als accumulator v a l v e s . T R U C K S U P P - SER VICE S E C T IO N 6 ENGINE C O N T E N T S OF T H IS S E C TIO N 6-1 6-2 Engine T une-U p.... Engine Mechanical D iagnosis................. 6-5 ENGINE TUNE-UP Refer to 1974 Service M anual for the following engine tune-up procedures: • Spark Plug Service • Compression Test • Ignition Service may occur. Disregard all references to performing a Cylinder Balance Test on 1976 vehicles that may be found in past or present model service publications. FUEL SYSTEM SERVICE • Generator Service Refer to Section 6M of this publication for fuel system, timing, idle speed and carburetor adjustment service procedures. • Drive Belts Service EMISSION SYSTEM SERVICE • Fuel Lines and Fuel Filter Service Refer to Section 6T of this publication for servicing emission system related components. • Battery Service • Cooling System Service • Instrument Check-Out • Additional Checks and Adjustments CAUTION: When performing engine diagnosis or tune-up on 1976 vehicles equipped with catalytic converters, DO NOT use the “Cylinder Balance Test” as described in 1974 Service Manual as damage to the emission control system IGNITION SYSTEM SERVICE Refer to Section 6Y of this publication for servicing High Energy Ignition (H E I) system. VEHICLE M AINTENANCE D uring engine tune-up, the Complete Vehicle Maintenance Schedule (or Section 0 of this m anual) should be checked and all required checks and services should be performed. TR U C K SUP P - S E R VIC E 6-2 ENG INE ENGINE MECHANICAL IN-LINE ENGINES COMPONENT REPLACEMENT AND ADJUSTMENT EXHAUST MANIFOLD ASSEMBLY 6. Remove starter on manual transmission equipped vehicles. Removal 1. Remove air cleaner. 2. Remove power steering pum p a n d /o r A .I.R. pump brackets (if so equipped). 7. Remove either flywheel underpan or converter housing underpan and splash shield. 8. Remove "through" bolts from engine front mounts. 9. Use a jacking device and raise engine approximately three inches. 3. Remove EFE valve bracket. 4. Disconnect throttle controls and throttle return spring. 5. Disconnect exhaust pipe at manifold flange. 6. Remove manifold attaching manifold and discard gasket. bolts; then, remove 10. Install “through” bolts in engine mount and tighten through bolts retaining nuts just enough to prevent bolts from slipping out. 11. Lower engine until through bolts are resting on frame portion of engine m ounts and then remove jacking device. 7. Check for cracks in manifold assembly. Installation 1. Clean gasket surfaces on cylinder head and mainfold. 12. Remove screws securing oil pan to engine and then remove oil pan. 2. Position new gasket on exhaust manifold. Installation (Fig. 4L) 3. Install manifold assembly bolts, while holding manifold assembly in place. 4. Clean, oil and torque all manifold to cylinder head bolts and nuts to specifications (fig. 1A). 1. Thoroughly clean all gasket sealing surfaces. 2. Use a new gasket set and install rear pan seal in rear main bearing cap. 3. Install front pan seal on crankcase cover, pressing tips into holes provided in cover. ©SSt 25/30 LBS FT 0 0 7 30/35 ( ^ / rF T 0 -----25/30 LBS| FT\ LBS FT O A <■> 4. Install side gaskets to engine block, using gasket sealer with sufficient body to act as a retainer. 5. Install oil pan by reversing the removal steps and tightening all retaining screws to specifications. F ig . 1 A - E x h a u s t M a n ifo ld t o C y lin d e r H e a d B o lt T ig h t e n in g S e q u e n c e an d T o rq u e 5. Connect exhaust pipe to manifold. 6. Connect throttle controls and throttles return spring. N U T(2) 7. Install air cleaner, start engine and check for leaks. OIL PAN Removal (Fig. 4L) THROUGH B O L K 2 ) 1. Disconnect battery negative cable. 2. Remove radiator upper mounting panel. ENGINE M O U N T(2) 3. Place a piece of heavy cardboard between fan and radiator. 4. Raise vehicle on hoist. 5. D rain engine oil. Fig. 4L--O il Pan R e p la c e m e n t ENG INE 6-3 ENGINE MECHANICAL V-8 ENGINES GENERAL INFORMATION All vehicles utilize a high energy ignition system. Using this system, the conventional external ignition coil and other related components are eliminated. Except for the following changes, all information listed in Section 6 Engine of the 1974 Light Truck Service Manual is applicable to the 1976 model. COMPONENT REPLACEMENT AND ADJUSTMENT INTAKE MANIFOLD The intake manifold removal and installation procedure remains basically the same except that a new carburetor heat choke tube assembly is used. Upon transfering components on manifold replacement operation the choke tube assembly must be removed and (with a new gasket) transfered to new manifold. CRANKCASE FRONT COVER The installation procedure for the small V8 crankcase front cover has been revised. The removal procedure as outlined on page 6-46 of the 1974 Light Truck Service M anual remains the same. The revised installation procedure is as follows: Installation 1. Clean gasket surface on block and crankcase front cover. 2. Use a sharp knife or other suitable cutting tool, to remove any excess oil pan gasket m aterial that may be protruding at the oil pan to engine block junction. 3. Apply a 1/8" bead of silicone rubber sealer, part num ber 1051435 (or equivalent) to the joint formed at the oil pan and cylinder block, as well as the entire oil pan front lip (fig. 1R). 4. Apply a 1/8" bead of silicone rubber sealer, part num ber 1051435 (or equivalent) to the bottom of the seal and place in position on cover. 5. Loosely install cover-to-block. NOTE: Insert the top four bolts loosely (approximately 3 turns). Install two 1/4-20 x 1/2" screws one on each side at the lower hole in the front cover. Apply a bead of silicone sealer on the bottom of the seal and install on cover (fig. 2R). Fig. 1 R -A re a s to A p p ly F ro n t C o v er S e a la n t 6. Tighten screws alternately and evenly while using drift or other suitable tool to align dowel pins in block to corresponding holes in cover (fig. 3R). 7. Remove the two l/4-20x 1/2" screws previously used to draw up cover and install remaining cover screws. 8. Complete installation as outlined in the 1974 Light Truck Service Manual. T R U C K SUP P - S E R VIC E 6-4 ENG INE ■ DOWEL P \ N l M (ONE AT EACH SIDE) Fig. 3 R -A lig n in g C o v er to D o w e l Pins Fig. 2 R—In s ta llin g F ro n t C over and S eal DIAGNOSIS EN G IN E FAILS TO S T A R T a. Clean and tighten loose battery term inal connections. Using battery hydrometer, check specific gravity, if low, recharge battery. Check battery state of charge indicator on Freedom type battery. b. Check for broken or loose ignition wires an d /o r ignition switch and repair or replace as necessary. c. Remove m oisture from spark plug wires an d /o r distributor cap. d. Inspect condition of distributor cap and rotor. Replace if damaged or cracked. e. Check inspect and regap spark plugs. Replace as necessary. f. Check for weak or faulty H E I System Coil as outlined in Section 6Y of this manual. g. Check carburetor float level, operation of secondary vacuum break solenoid, air valve and enrichm ent system as outlined in Section 6M of this manual. h. Inspect carburetor fuel filter for presence of water an d /o r impurities. Correct as necessary. i. Check choke mechanism for proper operation. Any binding condition which may have developed due to petroleum gum formation on the choke shaft or from damage should be corrected. j. Check fuel pump for leaks and proper operation. Correct as necessary. k. Check operation of starter m otor and solenoid. Repair or replace as necessary. 1. Inspect park or neutral safety switch. Adjust or replace as necessary. m. Check operation of EFE valve as outlined in Section 6T of this manual. Repair or replace as necessary. n. Check for air or vacuum leaks. Correct as necessary. TRUC K S U P P - SER VICE ENG INE 6-5 EN G IN E LOPES W H IL E ID L IN G a. Check for vacuum leaks and correct as necessary. b. Check for blown head gasket and repair as necessary. c. Inspect condition of camshaft, timing chain a n d /o r sprockets. Replace as necessary. d. Check engine operating tem perature and correct as necessary. e. Check the PCV system for satisfactory operation. Correct as necessary. f. Check fuel pump for leaks and proper operation. C orrect as necessary. g. Check operation of Exhaust Gas Recirculation valve. Repair or replace as necessary. h. Check ignition timing and operation of the H.E.I. system as outlined in Section 6Y of this manual. Correct as necessary. i. Check carburetor for incorrect idle speed, defective altitude compensator, sticking choke or enrichment system and adjust, repair o r replace as necessary. j. Check operation of EFE valve as outlined in Section 6T of this manual. Repair or replace as necessary. k. Check inspect and regap spark plugs. Replace if necessary. EN G IN E M IS S E S W H IL E ID L IN G a. Check, inspect and regap spark plugs. Replace as necessary. h. Inspect carburetor fuel filter for presence of water an d /o r impurities and correct as necessary. b. Remove moisture from distributor cap. spark plug wires a n d /o r i. Check carburetor m ounting gasket for air leaks. Repair as necessary. c. Check for broken or loose ignition wires. Repair or replace as necessary. j. Check distributor spark advance mechanism for proper operation. Repair or replace as necessary. d. Check condition of cylinders for uneven compression. Repair as necessary. k. Inspect valve train components. Adjust, repair an d /o r replace as necessary. e. Check for weak or faulty H E I system coil as outlined in Section 6Y of this manual. 1. Check engine for low compression. Repair as necessary. f. Inspect condition of distributor cap and rotor. Replace if damaged or cracked. g. Check carburetor for internal obstructions, incorrect idle speed, faulty altitude, com pensator sticking choke or enrichm ent system and adjust, repair or replace as necessary. m. Check operation of exhaust gas recirculation valve. Repair or replace as necessary. n. Check ignition timing, and condition of ignition system as outlined in Section 6Y of this manual. Correct as necessary. o. Check for vacuum leaks. Correct as necessary. p. Check operation of E FE valve as outlined in Section 6T of this manual. Repair or replace as necessary. TR U C K S UPP - S ER VIC E 6-6 ENGINE EN GIN E M IS S E S A T V A R IO U S SPEEDS a. Inspect carburetor fuel filter for presence of water an d /o r impurities. Correct as necessary. g- Detonation and pre-ignition may be caused by using sub-standard fuel. Correct as necessary. b. Check fuel system for leaks, plugged fuel lines incorrect fuel pump pressure a n d /o r plugged carburetor jets. Correct as necessary. h. Check for weak valve springs and condition of camshaft lobes. Repair or replace as necessary. c. Check ignition timing. Correct as necessary. i. Check engine necessary. operating temperature. Correct as d. Check for excessive play in distributor shaft. Repair or replace as necessary. j- Check operation of exhaust gas recirculation valve. Repair or replace as necessary. e. Check for weak or faulty H.E.I. system coil as outlined in Section 6Y of this manual. k. Inspect distributor cap for evidence of carbon tracking. Replace if necessary. f. Check, inspect and regap spark plugs. Replace as necessary. 1. Check for faulty altitude com pensator and incorrect carburetor adjustments. Correct as necessary. m. Check for vacuum leaks. Correct as necessary. n. Check operation of E FE valve as outlined in Section 6T of this manual. Repair or replace as necessary. EN GIN E STALLS j. Check engine for low compression. Repair as necessary. a. Check carburetor for incorrect an d /o r misadjusted idle speed, float level, leaking needle and seat, air valve, sticking choke or enrichment system and secondary vacuum break operation. Adjust, repair or replace as necessary. k. Check b. Inspect carburetor fuel filter for presence of water an d /o r impurities. Correct as necessary. 1. Check for loose, corroded or leaking wiring connections c. Check H.E.I. system as outlined in Section 6Y of this manual. d. Check, inspect and regap spark plugs. Replace as necessary. e. Check distributor spark advance mechanism for proper operation. Repair or replace as necessary. f. Inspect exhaust system for restrictions. Correct as necessary. g. Check carburetor m ounting gasket for air leaks. Repair as necessary. h. Check and adjust valve lash. i. Check for burned, warped or sticking valves. Repair or replace as necessary. engine operating tem perature. Correct as necessary. (bulk-head connectors etc.) R epair as necessary. m. Check operation of exhaust gas recirculation system. Repair or replace as necessary. n. Check fuel system for leaks a n d /o r obstructions. Repair as necessary. o. Check for vacuum leaks. Correct as necessary. p. Check operation of EFE valve as outlined in Section 6T of this manual. Repair or replace as necessary. T R U C K SUP P - SER VIC E ENGINE 6-7 EN GIN E H A S L O W P O W E R a. Check for weak or faulty H .E.I. system coil as outlined in Section 6Y of this manual. j. Check condition of cylinders for uneven compression an d /o r blown head gasket. Repair as necessary. b. Check ignition timing. Correct as necessary. k. Check power steering flow control valve operation. Repair or replace as necessary. c. Check for excessive play in distributor shaft. Repair or replace as necessary. d. Check, inspect and regap spark plugs. Replace as necessary. e. Check carburetor for incorrect a n d /o r misadjusted idle speed, float level, leaking needle and seat, air valve and sticking choke or enrichm ent system. Adjust, repair or replace as necessary. 1. Check for clutch slippage (vehicles with manual transmissions) and adjust or replace as necessary. m. Check hydraulic brake system for proper operation. Correct as necessary. n. Check engine necessary. operating temperature. Correct as o. Check pressure regulator valve (automatic transmission) for proper operation. Repair as necessary. f. Inspect carburetor fuel filter for presence of water a n d /o r impurities. Correct as necessary. p. Check transmission fluid level. Correct as necessary. g. Check fuel pump for leaks and proper operation. Correct as necessary. q. Loss of power may be caused by using sub-standard fuel. Correct as necessary. h. Check for sticking valves, weak valve springs, incorrect valve timing, lifter noise and worn camshaft lobes. Adjust, repair or replace as necessary. r. Check operation of EFE valve as outlined in Section 6T of this manual. Repair or replace as necessary. i. Check for insufficient piston to bore clearance. Correct as necessary. s. Check operation of diverter valve (A.I.R. system). Repair or replace as necessary. t. Check for engine vacuum leaks. Correct as necessary. ENGINE DIE SELING ON S H U T OFF a. Check base idle speed for im proper adjustment and correct as necessary. b. Check ignition timing and reset to specifications if required. c. Check idle mixture setting and correct as necessary. d. Check accelerator and choke linkage operation and correct as necessary. e. Check engine operating tem perature and correct as necessary. f. Check therm ae valve for sticking and correct as necessary. EN GIN E D E T O N A T IO N a. Check for overadvanced ignition timing an d /o r faulty ignition system and correct as necessary. h. Check E G R system operation and correct as necessary. i. Check therm ostatically controlled air cleaner operation and correct as necessary. b. Check for loose or im proper application of spark plugs, or spark plugs with cracked or broken ceramic cores and replace as necessary. j. Check P.C.V. necessary. c. Check for the use of sub-standard fuel and correct as necessary. k. Check for vacuum leaks and repair or replace as necessary. d. Check for foreign material in fuel lines an d /o r carburetor and correct as necessary. 1. Check engine operating tem perature and correct as necessary. e. Check for restricted fuel delivery to carburetor (pinched lines, faulty fuel tank cap or pick-up) and correct as necessary. m. Check for excessive combustion cham ber deposits and correct as necessary. f. Check fuel pump operation and replace if necessary. system operation and correct as n. Check for leaking, sticking, or broken valves and repair or replace as necessary. g. Check EFE system operation and repair or replace as necessary. T R U C K S UPP - S E R VIC E 6-8 ENG INE E X T E R N A L OIL LEAKAGE a. Check for improperly seated or fuel pump gasket. Replace as necessary. b. Check for improperly seated or broken push rod cover gasket. Replace as necessary. c. Check for improperly seated or broken oil filter gasket. Replace as necessary. d. Check for broken or improperly seated oil pan gasket. Replace as necessary. e. Inspect gasket surface of oil pan to be bent or distorted. Repair or replace as necessary. f. Check for im properly seated or broken timing chain cover gasket. Replace as necessary. g. Inspect timing cover oil seal. Replace if necessary. h. Check for worn or improperly seated rear main bearing oil seal. Replace if necessary. i. Inspect for loose oil line plugs. Repair or replace if necessary. j. Check for engine oil pan drain plug improperly seated. Correct as necessary. k. Inspect camshaft rear bearing obstructions. Correct as necessary. drain hole for 1. Check for loose rocker arm cover, broken, or cover distorted or bent. Correct as necessary. m. Check EFE valve switch for leakage. Replace if necessary. n. Check oil pressure switch for leakage. Replace if necessary. E X C E S S IV E OIL C O N S U M P T IO N DUE TO O IL E N TE R IN G C O M B U S T IO N C H A M B E R T H R O U G H H E A D A R E A a. Check for intake valve seals to be damaged, missing or loose. Repair or replace as necessaary. b. Check for worn valve stems or guides. Repair as necessary. c. Inspect for plugged oil drain back holes in head. Correct as necessary. d. Inspect PCV system operation. Correct as necessary. E X C E S S IV E OIL C O N S U M P T IO N DUE TO OIL EN TE R IN G C O M B U S T IO N C H A M B E R BY P A S S IN G P IS T O N R IN G S a. Check engine oil level too high. Correct as necessary. b. Check for excessive main or connecting rod bearing clearance and correct as necessary. c. Check for piston ring gaps not staggered and correct as necessary. d. Check for incorrect size rings installed and correct as necessary. h. Inspect rings sticking in ring grooves of piston and correct as necessary. i. Inspect ring grooves worn excessively in piston and correct as necessary. j. Inspect compression rings installed upside down and correct as necessary. e. Check for piston rings out of round, broken or scored and replace as necessary. k. Check for excessively worn or scored cylinder walls and correct as necessary. f. Inspect insufficient piston ring tension due to engine overheating and replace as necessary. 1. Inspect oil too thin and replace if necessary. g. Check for ring grooves or oil return slots clogged and corrected as necessary. m. Inspect mis-match of oil ring expander and rail and correct as necessary. TRUC K SUP P - S ER VIC E ENG INE 6-9 NO OIL PRESSURE W H IL E ID L IN G a. Check faulty oil gauge sending unit, and correct as necessary. c. Inspect for excessive clearance at main and connecting rod bearings and correct as necessary. b. Check for oil pump not functioning properly. (Regulator ball stuck in position by foreign material) and correct as necessary. d. Inspect for loose camshaft bearings and correct as necessary. e. Inspect leakage at internal oil passages and correct as necessary. NO OIL PRESSURE W H IL E A C C E L E R A T IN G a. Check low oil level in oil pan and correct as necessary. b. Inspect leakage at internal oil passages and correct as necessary. c. Check oil pum p suction screen loose or fallen off and correct as necessary. B U R N E D , S T IC K IN G OR BROKEN V A L V E S a. Check for weak valve springs and replace as necessary. b. Check for im proper valve lifter clearance and adjust as necessary. c. Check for im proper valve guide clearance an d /o r worn valve guides and correct as necessary. d. Check for out-of-round valve seats or incorrect valve seat width and correct as necessary. e. Check for deposits on valve seats an d /o r gum formation on stems or guides and correct as necessary. f. Check for warped valves or faulty valve forgings and correct as necessary. g. Check for exhaust back pressure and correct as necessary. h. Check im proper spark timing and correct as necessary. i. Check excessive idling and correct as necessary. N O IS Y V A LV E S a. Check and adjust valve lash if necessary. f. Inspect for pulled or loose rocker arm studs. Repair or replace as necessary. b. Check for excessively worn, dirty or faulty valve lifters. Replace if necessary. g. Check for bent push rods. Replace if necessary. c. Check for worn valve guides. Repair as necessary. h. Inspect for broken valve spring. Replace if necessary. d. Check for excessive run-out of valve seat or valve face. R epair as necessary. e. Check for worn camshaft lobes. Replace camshaft if necessary. TR U C K S U P P - S E R VIC E 6 -1 0 ENGINE N O IS Y P IS T O N S A N D R IN G S a. Check for excessive piston to bore clearance. Correct as necessary. b. Inspect for im proper fit of piston pin. Correct as necessary. c. Inspect for excessive accumulation of carbon in combustion chamber or on piston tops. Clean an d /o r repair as necessary. d. Check for connecting rods alignment. Correct as necessary. e. Inspect for excessive clearance between rings and grooves. Repair or replace as necessary. f. Check for broken piston rings. Replace as necessary. BROKEN P IS T O N S A N D /O R R IN G S a. Check for undersize pistons. Replace if necessary. b. Check for wrong type a n d /o r size rings installed. Replace if necessary. c. Check for tapered or eccentric cylinder bores. Correct as necessary. d. Check connecting rod alignment. Replace if necessary. e. Check for excessively worn ring grooves. Replace if necessary. f. Check for improperly assembled piston pins. Replace as necessary. g. Check for insufficient ring gap clearance. Correct as necessary. h. Inspect for engine overheating. Correct as necessary. i. Check for sub-standard fuel. Correct as necessary. j. Check ignition timing. Correct as necessary. N O IS Y C O N N E C T IN G R O D S a. Check connecting rods for improper alignment and correct as necessary. c. Check for eccentric or out-of-round crankshaft journals and correct as necessary. b. Check for excessive bearing clearance and correct as necessary. d. Check for insufficient oil supply and correct as necessary. e. Check for low oil pressure and correct as necessary. f. Check for connecting rod bolts not tightened correctly and correct as necessary. N O IS Y M A IN B E A R IN G S a. Check low oil pressure an d /o r insufficient oil supply and correct as necessary. b. Check for excessive bearing clearance and correct as necessary. c. Check for excessive crankshaft end play and correct as necessary. d. Check for eccentric or out-of-round crankshaft journals and correct as necessary. e. Check for sprung crankshaft and replace if necessary. f. Check for excessive belt tension and adjust as necessary. g. Check for loose torsional dam per and replace as necessary. TR U C K SUP P - SER VIC E ENG INE 6-11 N O IS Y V A L V E LIFTERS a. Check for broken valve springs and replace as necessary. b. Check for worn or sticking rocker arms and repair or replace as necessary. c. Check for worn or bent push rods and replace as necessary. d. Check for valve lifters incorrectly fitted to bore size and correct as necessary. e. Check faulty valve lifter plunger or push rod seat and replace lifters as necessary. f. Check for plungers excessively worn causing fast leakdown under pressure and replace as necessary. g. Check for excessively worn camshaft lobes and replace if necessary. h. Check valve lifter oil feed holes plugged causing internal breakdown and correct as necessary. i. Check faulty valve lifter check ball, (nicked, flat spot, or out of round and replace as necessary. j. Check rocker arm retaining nut to be installed upside down and correct as necessary. k. Check for end of push rod excessively worn or flaked and replace as necessary. S E C T IO N 6K ENGINE COOLING GENERAL W ith the exception of the following additions and changes, refer to Section 6K, Engine Cooling, and Section 13, Radiator and Grille, of the 1974 Light D uty T ruck Service M anual for maintenance and checking the engine cooling system. MAINTENANCE AND ADJUSTMENTS PRESSURE CHECKING COOLING SYSTEM FOR LEAKS The radiator cap is a pressure relief type. This cap is designed to m aintain a pressure of at least 15 psi in the cooling system once the engine has attained operating tem perature. The pressure cap relief valve located in the cap allows excessive pressure to escape through the overflow hose into a coolant recovery bottle. Using a J-24460 Cooling System Pressure Tester or equivalent, a J-23699 adapter and a J-23636 hose gauge, check the system for leaks in the following manner. 1. Make a visual check of hoses and hose connections for leaks and tighten clamps as required. 2. Using norm al precautions carefully remove the radiator cap. N E V E R R E M O V E R A D I A T O R C A P W H E N E N G I N E IS H O T . 10. If pressure drops below 15 psi in 10 seconds, the spring washer gasket may be leaking. To check proceed to Step 11. If pressure does not drop, proceed to Step 15. 11. Remove Pressure Tester, J-24460, from J-23699. Adapter, 12. Reconnect overflow hose to radiator neck nipple and carefully open the radiator cap, thus releasing pressure from the radiator into the radiator reservoir tank. 13. Check spring washer gasket on the radiator cap. This gasket seals between the cap and the top of the radiator filler neck. If defective, replace radiator cap. 14. Reconnect adapter per Step 8 and pump system to 15 psi and again check to determine if pressure drops below 15 psi in 10 seconds. 15. To check cap and system holding pressure, wiggle upper radiator hose to stabilize Hose Gauge, J-23636 and set red washer against the movable handle. 3. Wash the cap with clean water until gaskets appear clean. 16. Remove Pressure Tester, J-24460, from A dapter, J-23699. 4. Test cap using J-24460 Tester. Follow instructions furnished with the tester. If cap will not hold pressure within specified band, replace with a new radiator cap. 17. While system is under pressure examine all hoses, hose connections, radiator, heater, water pump and all gaskets for visible signs of leaking and repair or tighten as indicated. 5. Clean and inspect the radiator filler neck. The coolant level in the radiator should be within a 1/2 inch of the filler neck. Fill the radiator to this level with 50 percent ethylene glycol solution and replace the radiator cap, making sure it is on completely with the locking tangs against the stops. 18. After 5 minutes, wiggle hose again and note position of movable handle. 19. If handle has not moved more than a 1/4 inch in 5 minutes, cap is holding sufficient pressure. 8. Remove coolant recovery hose from radiator neck nipple and connect hose from A dapter J-23699. 20. If handle has moved more than a 1/4 inch check again for leaks, repressurize per step 9, remove Pressure Tester, J-24460 per Step 11 and insert hose in a glass of water so end is below liquid level and watch for bubbles. Presence of bubbles indicates a leaking radiator cap. Replace cap, if necessary. 9. Pump system to 15 psi and watch for a pressure drop on pump gauge. 21. If leaking is still indicated by moving handle of Hose Gauge, J-23636 and visible external leaks have been 6. Install Hose Gauge, J-23636, on upper radiator hose. 7. Install A dapter, J-23699, on Pressure Tester, J-24460. T R U C K SUP P - S E R VIC E 6K -2 ENG INE eliminated, then the leak must be internal and more complicated testing m ust be performed to determine which part must be repaired or replaced. Such internal leaks will be corrected by doing the following in this order. a. Torque the head bolts. b. Replace head gaskets. c. Replace heads. d. Replace engine block. RADIATOR REPLACEMENT All Except P 3 0 (3 2 ) Chassis Refer to Figure 1 through 4 for radiator assembly positions for C, K, G and P30(42) Series vehicles. Removal 1. Remove radiator cap when engine is cool by: • Slowly rotate cap counter clockwise to detent do not press down while rotating. • Wait until any residual pressure (indicated by a hissing sound) is relieved. • After hissing ceases, press down on cap while continuing to rotate counterclockwise. CAUTION: To a void the danger o f being burned, do not remove radiator cap while engine and radiator are hot because scalding fluid and steam will be blown out under pressure. 2. Open drain cock and drain radiator. 3. Disconnect upper and lower radiator hoses and transmission oil cooler lines or heater hose, if equipped. 4. Disconnect coolant recovery system hose. 5. If shroud installed, remove shroud to radiator screws and lift shroud out of lower clips and carefully hang Fig. 1 -R a d ia to r M o u n tin g - P 2 0 ( 4 2 ) Fig. 3 - R a d ia to r M o u n tin g - G S eries FINGER GUARD L - 6 E N G IN E V - 8 E N G IN E Fig. 4 - R a d ia to r S h ro u d - G S eries T R U C K SUP P - SER VIC E ENG INE 6K-3 shroud over engine fan assembly to provide clearance for radiator removal. 6. Remove finger guard (G Series, L6 engine only). 7. Remove radiator upper m ounting panel (retainers on G Series) from radiator support. Remove upper mounting pads. 8. Lift radiator out of the lower mountings and remove from vehicle. Lift shroud out of vehicle if applicable. Installation 1. Inspect mounting pads and mounting panel or retainers and replace as required. 2. W ith fan shroud positioned over fan, lower radiator into lower mountings and install radiator upper m ounting panel. On G Series with L6 engine, install finger guard. 3. Install fan shroud, if so equipped. 4. Connect upper and lower radiator hoses. Connect coolant recovery system hose. Inspect hose clamps and all hoses. Replace hoses whenever swollen, checked or otherwise deteriorated. 5. Connect transmission oil cooler lines and heater hose, if so equipped. 6. Remove coolant recovery tank and empty of fluid. Clean inside of tank thoroughly with detergent and water, scrubbing sides clean, and then flush with clean water and drain. 9. A dd sufficient ethylene glycol coolant, meeting GM specification 1899-M, to provide the required freezing and corrosion protection - at least a 50 percent solution (-20°F). Completely fill radiator and add sufficient coolant to the recovery tank to raise the level to the 7. Reinstall tank. 8. (C-K Models) Insert coolant recovery hose in tank as far as the first white stripe (Fig. 5). "Cold Level" mark. Reinstall recovery tank cap. 10. Pressure check cooling system. TRUC K SUP P - S ER VIC E 6K -4 ENG INE COOLANT RECOVERY SYSTEM Refer to Figures 5 through 8 for removal and installation of applicable coolant recovery system. Inside of coolant recovery tank should be clean before installing in a vehicle. Fig. 8 --C o o la n t R eco very S ystem - P 3 0 ( 3 2 ) T R U C K SUP P - SER VIC E S E C T IO N 6 M ENGINE FUEL C O N T E N T S OF T H IS S E C TIO N 1MV C arb u reto r.................................................................................. ..6M-1 2GC C a rb u re to r.................................................................................. ..6M-18 M 4M C /M 4M E C arburetor................................................................. 6M-31 4MV Quadrajet C arb u reto r................................................................ 6M-54 Accelerator C o n tro l............................................................................ .. 6M-65 Air C leaner........................................................................................... .. 6M-65 Fuel P u m p ............................................................................................ .. 6M-72 Special T o o ls........................................................................................... 6M-75 1 M V MONOJET CARBURETOR IN D E X General D escription......................................................... 6M-1 Theory of Operation........................................................ 6M-2 Float System ................................................................... 6M-2 Idle System ......................................................................6M-3 Main Metering System..................................................6M-4 Power Enrichm ent System...........................................6M-5 Accelerating Pum p System...........................................6M-5 Choke System ................................................................. 6M-6 M aintenance and A djustm ents...................................... 6M-7 Idle Speed........................................................................ 6M-7 Low Idle and Curb Idle Speed A djustm ent...................................................... 6M-7 Idle M ixture.................................................................... 6M-8 Idle M ixture A djustm ent...........................................6M-8 Fast Idle A d justm ent....................................................6M-8 Fast Idle Cam A djustm ent..........................................6M-8 Choke Coil Rod A djustm ent...................................... 6M-8 Primary Vacuum Break A d justm en t.........................6M-9 Auxiliary Vacuum Break A d justm ent...................... 6M-10 Choke Unloader A djustm ent...................................... 6M-10 Service Operations.............................................................6M-10 Carburetor R eplacem ent............................................... 6M-10 Fuel Filter R eplacem ent.............................................. 6M -11 Idle Stop Solenoid Replacem ent................................ 6M-11 Choke Coil R eplacem ent............................................. 6M -11 Air Horn Tightening Sequence...................................6M-12 D iagnosis............................................................................ 6M-13 GENERAL DESCRIPTION The Monojet carburetor is a single bore downdraft carburetor (fig. 1) using a triple venturi in conjunction with a plain tube nozzle. The main venturi is 1-5/16" in diameter and the throttle bore is 1-11/16". during periods of extreme hot engine operation. The model MV incorporates an automatic choke system. The vacuum diaphragm units are mounted externally on the air horn and connect to the therm ostatic coil lever through a connecting link. The automatic choke coil is manifold mounted and connects to the choke valve shaft by a rod. Fuel flow through the main metering system is controlled by a main well air bleed and a variable orifice jet. A power enrichment system is used to provide good performance during moderate to heavy accelerations and at higher engine speeds. An integral, pleated-paper fuel inlet filter is mounted in the fuel bowl behind the fuel inlet nut to give maximum filtration of incoming fuel. On a vehicle with autom atic transmission and air conditioning, the idle system incorporates a hot idle compensator (A.T. only) to maintain smooth engine idle The Monojet carburetor has an aluminum throttle body for decreased weight and improved heat distribution and a thick throttle body to bowl insulator gasket to keep excessive TRUC K SUP P - SER VIC E 6 M -2 ENG INE FUEL the air cleaner. CHOICE SHAFT AND LEVER ASSEMBLY AUXILIARY CHOKE VAC U U M BREAK PRIMARY CHOKE VAC U U M BREAK DIAPHRAGM The carburetor model identification is stamped on a vertical portion of float bowl, adjacent to fuel inlet nut (Figure 1). If replacing float bowl, follow m anufacturer’s instructions contained in the service package so that the identification number can be transferred to the new float bowl. An electrically operated idle stop solenoid is used on all 1MV models. Dual throttle return springs are used on all carburetors. CHOKE ROD All carburetor models have an idle mixture-screw and limiter. The plastic limit cap perm its idle mixture screw to be adjusted leaner without breaking the cap. At carburetor overhaul, the mixture may be adjusted. C A U T I O N : Do not bend the mixture screw when cutting the tang. IDLE STOP SOLENOID THROTTLE LEVER FAST IDLE CAM To get the best idle and keep emissions within standards set by law, always follow adjustm ent procedures and specifications, see “ Idle M ixture A djustm ent” . An Exhaust Gas Recirculation system (E.G.R.) is used on all applications to control oxides of nitrogen. Fig. 1 -1 M V M o n o je t C a rb u re to r engine heat from the float bowl. The carburetor has internally balanced venting through a vent hole in the air horn, which leads from the float bowl into the bore beneath The vacuum supply port necessary to operate the recirculation valve is located in the throttle body and connects through a channel to a tube which is located at the top of the air horn casting. Six basic systems of operation are used: float, idle, main metering, power enrichment, pum p and choke. THEORY OF OPERATION FLOAT SYSTEM (Fig. 2) The float system controls the am ount and level of the fuel in the carburetor float bowl. H igher than specified fuel levels can cause flooding, hard, hot starting, rich fuel mixtures causing poor economy, nozzle drip at idle and stalling. Therefore, it is im portant that the float be set to recommended specifications. The float system on the Monojet carburetor is located adjacent to the main venturi. It is designed so that angular maneuvers such as steep hills and sharp turns will not affect proper operation by keeping an adequate supply of fuel in the bowl at all times. The float system consists of the following: a fuel inlet filter and pressure relief spring, a solid single pontoon float made of special lightweight plastic, a conventional needle and seat and a float hinge pin. The float hinge pin fits in dual slots cast in the float bowl and is held in place by compression of the air horn gasket against the upper loop of the hinge pin. The float operates as follows: fuel from the engine fuel pump is forced through the paper fuel inlet filter, located behind the fuel inlet nut, passes from the filter chamber up through the float needle seat and spills into the float bowl; as the float bowl fills with fuel, it lifts the float pontoon upward until the correct fuel level is reached in the float bowl. A t this point, the float arm forces the float needle against the float needle seat, shutting off fuel flow. As fuel is used from the float bowl, the float drops downward, allowing the float needle to move off its seat and more fuel to enter the float bowl. This cycle continues throughout engine operation, constantly m aintaining a positive fuel level in the float bowl. The fuel inlet filter has a retention spring located at the rear of the filter. It seats between the rear of the filter and the inlet casting. Should the filter become clogged from improper servicing or excess dirt in the system, the retention spring will keep the filter on its seat. This will stop complete stoppage of fuel flow to the carburetor until the filter can be replaced. The carburetor float chamber is internally vented through a hole located in the air horn above the float chamber. The purpose of the internal vent is to balance air pressure on the fuel in the float bowl with carburetor inlet air. W ith this feature, a balanced air/fuel mixture ratio can be maintained during part throttle and power operation because the air pressure acting on the fuel in the float bowl will be balanced with the air flowing through the carburetor bore. TRUC K S UPP - SER VIC E ENG INE FUEL 6 M -3 TOP AIR BLEED 'E .G .R . (EXH AU ST GAS RECIRCULATION) TUBE TO E.G.R * VALVE IN T E R N A L V E N T PRESSURE R E L IE F V A L V E IDLE CHANNEL RESTRICTION V E N T H O LE IDLE TUBE I FLOAT H IN G E PIN FLO AT FLO AT NEEDLE ' .M A IN METERING JET HOT IDLE COMPENSATOR TIMED VA C U U M PORTS FOR E.G.R. NEEDLE SEAT F IL T E R R E L IE F S PR IN G FU E L IN L E T F IL T E R THROTTLE VALVE IDLE M IX TU R E NEEDLE IDLE DISCHARG E HOLE OFF— IDLE OPER ATION Fig. 3 - ld le S ystem Fig. 2 - F lo a t S ystem The carburetor float cham ber is externally vented by a small plastic pressure relief valve located at the top of the air horn. Should excessive vapor pressure build up in the float bowl during periods of hot engine idle or hot soak, the valve will be pushed off its seat, allowing the pressure to be relieved, there-by preventing fuel from being forced from the float bowl into the engine. IDLE SYSTEM (Fig. 3) The purpose of the idle system is to control fuel mixtures to the engine during idle and low speed operation. The idle system is needed during this period because air requirements of the engine are not great enough to obtain efficient metering from the main discharge nozzle and venturi system. The idle system consists of a removable idle tube, idle passages, idle channel restriction, idle air bleeds, slotted off-idle port, vapor canister purge ports, exhaust gas recirculation (E.G .R.) ports and passages, idle mixture adjusting needle and the idle m ixture discharge hole. D uring curb idle, the throttle valve is held slightly open by the idle stop solenoid. The small am ount of air, which passes between the throttle valve and bore, is regulated by solenoid to provide the correct engine idle speed. Since the engine requires very little air and fuel for idle and low speed operation, fuel is mixed by direct application of engine manifold vacuum to the idle discharge hole just below the throttle valve. W ith the idle discharge hole in a very low pressure area and the fuel in the float bowl vented to atmosphere, fuel flows through the idle system as follows: Atm ospheric pressure forces fuel from the float bowl down through the main metering jet into the main fuel well where it is picked up and metered at the lower tip of the idle tube. It passes up the idle tube and is mixed with air at the top of the idle channel through the idle air bleed hole. The air/fuel mixture passes over through the cross channel and then downward through the calibrated idle channel restriction where it is further metered. The mixture continues down the idle passage past the lower idle air bleed hole and off-idle discharge port just above the throttle valve, where it is again mixed with air. The air/fuel mixture then moves downward past the idle mixture needle and out through the idle discharge hole into the carburetor bore. Here it mixes with the air passing around the slightly open throttle valve and then continues through the intake manifold into the engine cylinders as a combustible mixture. OFF-IDLE OPERATION As the throttle valve is opened from curb idle to increase engine speed, additional fuel is needed to combine with the extra air entering the engine. This is accomplished by the slotted off-idle port. As the throttle valve is opened, it passes the off-idle port, gradually exposing it to high vacuum below the throttle valve. The additional fuel from the off-idle port mixes with the increased air flow past the opening throttle valve to meet increased engine air and fuel demands. F urther opening of the throttle valve causes increased air flow through the carburetor bore, which causes sufficient pressure drop in the multiple venturi to start fuel delivery from the main discharge nozzle. The off-idle port fuel discharge does not cease at this transfer point but rather diminishes as fuel flow from the main discharge nozzle increases. In this way, the systems are so designed that they combine to produce a smooth fuel flow at all engine speeds. The lower idle air bleed is used strictly as an air bleed during idle operation. It supplies additional air to the idle circuit for improved atom ization and fuel control at low engine speeds. The same air bleed is used as an additional fuel feed at higher engine speeds to supplement main discharge nozzle delivery during operation of the main metering system. TRUC K SUPP - S E R VIC E 6 M -4 ENG INE FUEL The timed spark port has one tube which supplies vacuum during the off-idle and part throttle operation of the carburetor. The tube leads to the purge valve on the vapor canister to provide a means of pulling fuel vapors from the canister during periods of higher air flow through the carburetor bore. A limited am ount of canister purge is also provided by a separate tube which leads from the canister to the PCV valve hose connection. An exhaust gas recirculation (E.C.R.) system is used on all models to control oxides of nitrogen emissions. The E.G.R. valve is operated by a vacuum signal taken from the carburetor throttle body. A vacuum supply tube installed in the carburetor air horn connects by a passage through the float bowl to the timed vertical port in the throttle body bore. This provides a vacuum signal to the E.G.R. valve in the off-idle and part throttle operation of the carburetor. The purpose of the E.G .R. system is to supply a metered am ount of exhaust gases to the combustion mixtures and lower combustion temperatures, thereby reducing oxides of nitrogen during these ranges of engine operation. Hot Idle Compensator The hot idle com pensator (Figure 3), with automatic transmission and air conditioning only, is located in a chamber on the float bowl casting, adjacent to the carburetor bore, on the throttle lever side of the carburetor. Its purpose is to offset enrichening effects caused by changes in air density and fuel vapors generated during hot engine operation. The com pensator consists of a therm ostatically controlled valve, a bi-metal strip which is heat sensitive, a valve holder and bracket. The valve closes off an air channel which leads from a hole inside the air horn to a point below the throttle valve where it exists into the throttle body bore. Normally, the com pensator valve is held closed by tension of the bi-metal strip and engine vacuum. D uring extreme hot engine operation, excessive fuel vapors in the carburetor can enter the engine manifold causing richer than normally required mixtures. This can result in rough engine idle and stalling. A t a pre-determined tem perature, when extra air is needed to offset the enrichening effects of fuel vapors, the bi-metal strip bends and unseats the com pensator valve, uncovering the air channel leading from the compensator valve chamber to the throttle body bore. This allows enough air to be drawn into the engine manifold to offset the richer m ixtures and maintain a smooth engine idle. W hen the engine cools and the extra air is not needed, the bi-metal strip closes the valve and operation returns to normal. point where the valve automatically closes for proper idle adjustment. CAUTION: Always remove plug used in inlet hole after completing idle adjustment, otherwise, the compensator will not operate. M A IN METERING SYSTEM (Fig. 4) The main metering system supplies fuel to the engine from off-idle to wide open throttle operation. It feeds at all times when air flow through the venturi is great enough to m aintain efficient fuel flow from the main discharge nozzle. The triple venturi stack-up used in the Monojet carburetor is very sensitive to air flow, which results in a finer and more stable metering control from light to heavy engine loads. The main metering system consists of a main metering jet, mechanical and vacuum operated metering rod, main fuel well, main well air bleeds, fuel discharge nozzle and triple venturi. The main metering system operates in the following manner: As the throttle valve is opened beyond the off-idle range, allowing more air to enter the engine manifold, air velocity increases in the carburetor venturi. This causes a drop in pressure in the main venturi which is increased many times in the double boost venturi. Since the lower pressure (vacuum) is now in the smallest venturi, fuel flows from the main discharge nozzles in the following manner: Fuel in the float bowl passes between the tapered metering rod and the main metering jet where it is metered and flows on into the main fuel well. In the main well the fuel is mixed with air from the air bleed at the top of the well and another air bleed which leads into the main well from the discharge nozzle cavity. A fter the fuel in the main well is mixed with air from the air bleeds it then passes up the discharge nozzle where it sprays into the small boost venturi. A t the boost venturi, the fuel mixture then combines with air entering the engine through the carburetor bore to provide the correct air/fuel mixtures to the engine for efficient combustion. The com pensator valve assembly is held in place by the dust cover over the valve chamber. A seal is used between the compensator valve and float bowl casting. In order to insure proper idle adjustm ent when the engine is hot, the com pensator valve m ust be closed. To check this, plug the compensator inlet hole inside the air horn bore (pencil can be used). If no drop in engine rpm is noted on a tachom eter, the valve is closed; if the valve is open, leave plug in hole when adjusting idle or cool engine down to a T R U C K S U P P - S ER VIC E ENG INE FUEL 6 M -5 Fuel flow to the main discharge nozzle is controlled by a tapered metering rod which is actuated by linkage connected directly to the throttle shaft. As the throttle valve is opened from idle position, the tapered metering rod is gradually raised out of the main metering jet orifice. Fuel flow from the main discharge nozzle is controlled by throttle opening and the depth of the metering rod in the main metering jet orifice. W ith the fuel metering mechanically controlled by the throttle valve angle, it is possible to m aintain very accurate m ixture ratios throughout part throttle to wide open throttle operation. An initial metering rod adjustment is required to set the depth of the rod in the main metering jet. M A IN DISC H A R G E NOZZLE POWER P IS TO N D R IV E ROD BOOST V E N T U R I, M A IN V E N T U R U M A IN M E TE R IN G POW ER PISTO N A C T U A T IN G L IN K A G E CAUTION: It should be noted here that there is a supplementary fuel feed passage in the bottom o f the float bowl adjacent to the main metering jet. Fuel is picked up from the float bowl and passes through a calibrated hole, past a calibration screw and on into the same fuel passage which leads from the main metering je t to the main fuel well. The purpose o f the adjustable fuel feed is to allow the factory to refine part throttle calibration to meet very accurate air/fuel mixture ratios. This adjustment is made using very sensitive instrumentation and the screw should not be tampered with or it will require complete float bowl or unit replacement. POWER ENRICHM ENT SYSTEM (Fig. 5) The vacuum operated power enrichm ent system is used to slightly enrichen m ixture ratios during m oderate to heavy loads during acceleration. The necessary enrichm ent is obtained by movement of a spring loaded vacuum piston which senses changes in manifold vacuum. The am ount of enrichm ent is controlled by the clearance between the groove in the power piston and the diameter of the power piston drive rod. D uring part throttle and cruising ranges, manifold vacuum is sufficient to hold the power piston down against spring tension. The upper part of the groove in the power piston is held down against the top side of the drive rod. This places the main metering rod lower in the jet for maximum economy. On m oderate to heavy accelerations, manifold vacuum drops and the power piston spring pushes the power piston up so that the ower edge of the slot in the power piston strikes the bottom side of the drive rod. This moves the tapered metering rod slightly upw ard and out of the main metering jet, allowing more fuel to flow through the jet, enrichening the fuel m ixture slightly. POWER PISTO N V A C U U M LOWER IDLE A IR BLEED F ig . 5 - P o w e r E n ric h m e n t S y s te m can feed the fuel required. The accelerating pum p is located at the side of the main fuel bowl, adjacent to the venturi area. It consists of a spring loaded pump plunger and pum p return spring operating in a fuel well. The pump plunger is connected by linkage directly to a lever on the throttle shaft. When the pump plunger moves upward in the pump well, as happens during throttle closing, fuel from the float bowl enters the pump well through a slot in the side of the pump well and flows past the synthetic pum p cup seal into the bottom of the pum p well. The pump cup is a floating type (the cup moves up and down on the pump plunger head). When the pump plunger is moved upward, the flat on the top of the cup unseats from the flat on the plunger head and allows free movement of fuel through the inside of the cup into the bottom of the pum p well. This also vents any vapors "T " DISCHARGE SPRING RETAINER ■PUMP LEVER PUMP PLUNGER '& D U R A TIO N SPRING PUMP DISCHARGE SPRING & BALL ACCELERATING PUMP SYSTEM (Fig. 6) Extra fuel for smooth, quick acceleration is supplied by a double spring loaded pump plunger. Rapid opening of the throttle valve, when accelerating from low speed, causes an immediate increase in air flow through the carburetor bore. Since fuel is heavier than air, it requires a short period of time for fuel flow through the main discharge nozzle to catch up with the air flow. To avoid leanness during this mom entary lag in the fuel flow, the accelerator pump furnishes a metered quantity of fuel which is sprayed into the air stream. This mixes with the increased air flow to supply the extra fuel needed until the main discharge nozzles PUMP RETUR N SPRING PUMP A C TU ATING LIN K PUMP CUP O PERATION Fig. 6 - A c c e l e r a t i n g P um p S ys te m TRUC K SUP P - S E R VIC E 6 M -6 ENG INE FUEL which may be in the bottom of the pump well so that a solid charge of fuel can be maintained in the fuel well beneath the plunger head. When the throttle valve is opened, as happens during acceleration, the connecting pump linkage forces the pump plunger downward. The pum p cup seats instantly and fuel is forced through the pum p discharge passage, where it unseats the pum p discharge check ball and passes on through the passage to the pump jet located at the top of the float bowl, where it sprays into the boost venturi area. The pump plunger is spring loaded; the upper duration spring is balanced with the bottom pump return spring so that a smooth sustained charge of fuel is delivered during acceleration. The pum p discharge check ball prevents any pull over or discharge of fuel from the pum p jet when the accelerator pump is not in operation. It also keeps the pump discharge passage filled with fuel to prevent pump discharge lag. The pump does not require adjustment in service as it is preset during manufacture. CHOKE SYSTEM (Fig. 7) The purpose of the choke system is to provide a richer mixture for cold engine starting and operation. Richer than norm al mixtures are required because vaporized fuel has a tendency to condense on cold engine parts. This occurs on the inside area of the intake manifold and cylinder heads, thereby, decreasing the am ount of combustible mixture available in the engine cylinders. The model MV carburetor is equipped with a fully automatic choke control. The therm ostatic coil is m ounted on the head and is connected by a link to the lever on the choke valve shaft. The vacuum break units are diaphragm operated and externally m ounted on the air horn casting. The choke system operates as follows: when the engine is cold, prior to starting, depressing the accelerator pedal to the floor opens the carburetor throttle valve. This allows tension from the therm ostatic coil to close the choke valve and also rotates the fast idle cam so the high step is in line with the fast idle cam follower on the throttle lever. As the throttle is released, the fast idle cam follower comes to rest on the high step of the fast idle cam, thus providing enough throttle valve opening to keep the engine running after cold start. D uring cranking, engine vacuum below the choke valve pulls fuel from the idle circuit and main discharge nozzle. This provides adequate enrichm ent for good cold starts. Fig. 7 - C h o k e S y s te m to choke coil cooling, causing the choke valve to be too far closed. The auxiliary diaphragm unit is controlled by a vacuum switch which is operated by engine coolant temperature. When the engine is started at tem peratures above 80°F., the vacuum switch opens and allows manifold vacuum to be applied to the auxiliary vacuum break diaphragm. The diaphragm unit pulls the choke valve to a nearly open position overcoming choke coil tension. At the same time the fast idle cam drops so that the fast idle cam follower tang rests on the lowest step of the fast idle cam. This maintains some fast idle until the engine warms up. When the engine is warmed up the choke coil pulls the choke valve fully open and the fast idle cam rotates so the fast idle cam follower tang drops off the low step, at which point the engine will When the engine starts, manifold vacuum is transm itted through a vacuum channel to the prim ary vacuum break diaphragm unit m ounted on the air horn casting. This moves the diaphragm plunger until it strikes the cover which, in turn, opens the choke valve to a point where the engine will run w ithout loading or stalling. This is called the vacuum break position. The auxiliary vacuum break unit (Fig. 8) is used to open the choke valve to a nearly wide open position during warmer tem peratures above 80°F. This prevents too rich a mixture when starting a cold engine during warm tem peratures due TR U C K S U P P - SER VIC E ENGINE FUEL 6 M -7 run at curb idle speed. As the engine warms up, the therm ostatic coil is heated and gradually relaxes its spring tension so that air velocity through the air horn can continue to open the choke valve. This continues until the engine is warm. A t this point the choke coil tension is completely relaxed and the choke valve is wide open. The fast idle cam has graduated steps so that fast idle engine speed is lowered gradually during the engine warm up period. The fast idle cam follows rotation of the choke valve. W hen the choke valve is completely open and the engine is warm, the fast idle tang on the throttle lever will be off the steps of the fast idle cam. A t this point, the idle stop solenoid controls normal engine idle speed. An unloader mechanism is provided should the engine become flooded during the starting period. The unloader partially opens the closed choke valve to allow increased air flow through the carburetor to lean out the overly rich mixtures. This is accomplished by depressing the accelerator pedal to the floor so that wide open throttle is obtained. When this is done, a tag on the throttle lever contacts an arm on the fast idle cam and forces the choke valve partially open. The extra air leans out the fuel mixture enough so that the engine will start. MAINTENANCE AND ADJUSTMENT IDLE SPEED Two idle speeds are required and are controlled and adjustable by the idle stop solenoid. The purpose of two idle speeds is to prevent dieseling when ignition is turned off. One speed is Curb Idle Speed which is normal engine idle and solenoid is energized. The second speed is Low Idle Speed and when solenoid is de-energized the carburetor throttle plate closes further than at norm al engine idle. Low Idle and Curb Idle Speed Adjustment (Fig. 9) Refer to Vehicle Emission Control Inform ation label on vehicle for latest certified specification information which may differ from specifications in manual. 1. W ith engine at normal operating tem perature, air cleaner on, choke open, and air conditioning O FF except where indicated, connect a tachom eter to engine. 2. Set parking brake and block drive wheels. 3. Disconnect and plug carburetor and PCV hoses at vapor canister on vehicle with light duty emissions. Disconnect fuel tank hose at vapor canister on vehicle with heavy duty emissions. 4. Disconnect vacuum advance hose at distributor and plug hose. 5. Start engine, check timing and adjust as required. 6. On engine with full vacuum advance, connect vacuum advance hose, otherwise, leave hose disconnected and plugged. 7. On vehicle with heavy duty emissions, turn conditioning ON. air 8. Position manual transmission in Neutral. Position autom atic transmission in Drive with light duty emissions or in N eutral with heavy duty emissions. 9. Turn solenoid in or out to set curb idle speed to specified rpm. 10. Disconnect electrical connector at idle stop solenoid and turn air conditioning O FF. 11. Turn 1/8" hex screw located in end of solenoid body to set low idle speed to specified rpm. 12. Reconnect electrical connector to solenoid and crack throttle slightly. 13. Check fast idle speed referring to fast idle adjustment procedure. 14. Shut off engine and remove tachometer. TRUC K SUP P - SER VIC E 6 M -8 ENG INE FUEL 15. Unplug and connect carburetor and PCV hoses at vapor canister on light duty emissions or fuel tank hose on heavy duty emissions. 16. If disconnected, connected vacuum advance hose. IDLE MIXTURE The idle mixture is factory preset and idle m ixture screw is capped with a plastic limiter cap. The cap permits screw to be turned about one turn leaner (clockwise) without breaking cap. The idle mixture is set to achieve the smoothest idle while m aintaining emission levels within standards prescribed by Federal Law. A t major carburetor overhaul the idle m ixture may be adjusted. Before suspecting idle m ixture as cause of poor idle quality, check ignition system, distributor, timing, air cleaner, PCV system, evaporation emission control and compression pressures. Also check all vacuum hoses and connections for leaks and check torques of carburetor attachm ent bolts. Adjustm ent is made using a tachometer. IDLE MIXTURE ADJUSTM ENT 1. W ith engine at normal operating temperature, air cleaner on, choke open, and air conditioning O FF, connect a tachom eter to engine. 2. Set parking brake and block drive wheels. 3. Disconnect carburetor and PCV hoses at vapor canister and plug on light duty emission vehicle or fuel tank hose at vapor canister on heavy duty vehicle. 4. Disconnect vacuum advance hose at distributor and plug hose. 5. Start engine, check timing and adjust as required. Reconnect vacuum advance hose. 6. On engine with full vacuum advance, connect vacuum advance hose, otherwise, leave hose disconnected and plugged. 7. Position autom atic transmission in Drive with light duty emissions or N eutral with heavy duty emissions. Position m anual transmission in Neutral. 8. Remove air cleaner and cut off tab on lim iter cap. Do not remove cap from screw. Install air cleaner. 9. Turn idle m ixture screw clockwise (leaner) or counterclockwise (richer) until maximum idle speed is achieved. 10. Set idle speed to higher specified rpm by turning solenoid in or out (Example 5 7 5 /550). 11. Observe tachom eter and turn idle mixture screw clockwise (leaner) until idle speed is at lower specified rpm (Example 575/ 5 5 0 ). 2. W ith engine at normal operating temperature, air cleaner on, choke open, E G R valve signal line disconnected and plugged and air conditioning OFF, connect tachom eter to engine. 3. Disconnect vacuum advance hose at distributor and plug hose on an engine with ported spark vacuum advance. 4. Start engine and with transmission in Neutral, set fast idle cam follower so that tang is on high step of cam. 5. Bend tang in or out to obtain fast idle RPM. FAST IDLE CAM ADJUSTM ENT (Fig. 11) 1. Check fast idle speed and adjust as required. 2. Set fast idle cam follower firmly on second stop of cam. 3. Rotate and hold choke valve tow ard closed position by applying force to choke coil rod. 4. Insert specified gauge between upper edge of choke valve and inside air horn wall. 5. Bend cam-to-choke rod as required to obtain clearance. CHOKE COIL ROD ADJUSTM ENT (Fig. 12) Light Duty Emissions (Fig. 12) 1. Disconnect upper end of choke coil rod at choke valve. 2. Completely close choke valve. 3. Push up on choke coil rod to its end of travel. 4. Bottom of rod should be even with top of lever. 5. If adjustm ent is required, bend rod. 6. Connect rod to choke valve. Heavy Duty Emissions (Fig. 12A) 12. Shut off engine and remove tachometer. 1. Disconnect upper end of choke coil rod at choke valve. 13. Connect all hoses to vapor canister. 2. Completely close choke valve. 14. Connect vacuum advance hose if disconnected. 3. Push down on choke coil rod to its end of travel. FAST IDLE ADJUSTM ENT (Fig. 10) 4. Top of rod should even with bottom of hole of choke lever. 1. Check low and curb idle speed and adjust as required. T R U C K SUP P - SER VIC E E NG INE FUEL 6 M -9 5. If adjustm ent is required, bend rod. Fig. 1 2 A ~ C h o k e C o il R od A d ju s tm e n t - H e a v y D u ty E m is s io n s 6. Connect rod to choke valve. PRIM ARY V ACUU M BREAK ADJUSTM ENT seated. 4. Push up on choke coil lever rod in end of slot. (Fig. 14) 1. Place cam follower on highest step of fast idle cam. 2. Plug purge bleed hole with masking tape over vacuum break end cover. 3. Using an outside vacuum source, apply vacuum to prim ary vacuum break diaphragm until plunger is fully 5. Insert specified gauge between upper edge of choke valve and air horn wall. 6. If adjustment is required, bend vacuum break rod. 7. After adjustment, make sure there is no interference or binding and remove tape from vacuum break end cover. B O T T O M OF ROD SH O U LD BE EVEN W IT H TOP OF LEVER < ^ - ( T ) c h o k e V A LVE ' C O M PLETELY CLOSED 2 ) PULL UP O N R O D TO E N D OF TR A VEL' R O D S H O U L D BE A G A IN S T STOP IN H O U S IN G NOTE: TO A D J U S T , R E M O V E R E T A IN IN G C L IP A N D UPPER END OF C H O K E C O IL ROD R E C O N N E C T AFTER ADJUSTM ENT. IN S T A L L R E T A IN IN G CLIP. F ig . 1 2 -C h o k e C o il R od A d ju s tm e n t - Lt. D u ty E m is s io n s TRUC K SUP P - S E R VIC E 6 M -1 0 ENG INE FUEL AUXILIARY V A C U U M BREAK ADJUSTM ENT (Fig. 14) Light Duty Emissions 4. If adjustm ent is required, bend link between vacuum break and choke valve. CHOKE UNLOADER ADJUSTM ENT (Fig. 15) 1. Position cam follower on highest step of fast idle cam. 2. Using an outside vacuum source, apply vacuum to auxiliary vacuum break diaphragm until plunger is fully seated. 3. W ith vacuum break diaphragm in fully seated position, insert specified gauge between upper edge of choke valve and inner air horn wall. 1. Hold down on choke valve by applying a light force to choke coil lever. 2. Rotate throttle valve to wide open position. 3. Insert specified gauge between upper edge of choke valve and air horn wall. 4. If adjustment is required, bend tang on throttle lever. SERVICE OPERATIONS CARBURETOR REPLACEMENT (Fig. 16) Removal Flooding, stumble on acceleration and other performance complaints are, in many instances, caused by presence of dirt, water, or other foreign m atter in carburetor. To aid in diagnosing cause, carburetor should be carefully removed from engine w ithout draining fuel from bowl. Contents of fuel bowl may then be examined for contam ination as carburetor is disassembled. Check filter. 1. Remove air cleaner and gasket. 2. Disconnect fuel and vacuum lines from carburetor. 7. Remove carburetor attaching nuts and remove carburetor and solenoid assembly attachm ent. 8. Remove insulator. Installation It is good shop practice to fill carburetor bowl before installing carburetor. This reduces strain on starting m otor and battery and reduces the possibility of backfiring while attem pting to start engine. A small supply of fuel will enable carburetor to be filled and the operation of float and intake needle and seat to be checked. Operate throttle lever several times and check discharge from pum p jets before installing carburetor. 3. Disconnect choke coil rod. 4. Disconnect accelerator linkage. 5. Disconnect idle stop solenoid electrical connector. 6. If equipped with autom atic transmission, disconnect detent control cable. 1. Be certain throttle body and intake manifold sealing surfaces are clean. 2. Install carburetor insulator. TRUC K SUP P - S ER VICE ENG INE FUEL 6 M - 1 1 CLIP SPR IN G FILTER IN S U L A T O R CH OK E GASKET T O R Q U E SEQUENCE T IG H T E N N U TS TO 36 IN. LBS. . . .T H E N TO 18 FT. LBS. H E A T STO VE F ig . 1 6 - C a r b u r e to r , C h o k e a n d H e a t S to v e F ig . 1 7 -F u e l F ilte r - M o n o je t 3. Install carburetor over manifold studs. IDLE STOP SOLENOID REPLACEMENT 4. Install vacuum and fuel lines at carburetor. The idle stop solenoid should be checked to assure that it 5. Install attaching nuts and tighten securely. permits the throttle plate to close further when the ignition 6. Tighten fuel and vacuum lines. switch is turned "off". An inoperative solenoid should be 7. Connect accelerator linkage. replaced. 8. Connect choke coil rod and idle stop solenoid electrical connector. 9. G uide vent tube into rocker cover and install air cleaner. 10. Refer to M aintenance and Adjustm ent and adjust low and curb idle speeds. Removal 1. Remove carburetor air cleaner. 2. Disconnect electrical connector at solenoid. 3. Unscrew and remove idle stop solenoid. Installation FUEL FILTER REPLACEMENT (Fig. 17) 1. Hold choke valve wide open so that fast idle cam follower clears fast idle cam. A plugged fuel filter will restrict fuel flow into carburetor 2. Install idle stop solenoid and turn in until it contacts lever tang. and will result in a loss of engine power. 3. Connect electrical connector. 1. Disconnect fuel line connection at inlet fuel filter nut. 4. Install air cleaner. 2. Remove inlet fuel filter nut from carburetor. 5. Refer to M aintenance and Adjustm ent and adjust low and curb idle speeds. 3. Remove filter element and spring. 4. Install element spring and filter element in carburetor. 5. Install new gasket on inlet fitting nut and install nut in carburetor and tighten securely. 6. Install fuel line and tighten connector. CHOKE COIL REPLACEMENT Choke mechanism should be checked for free operation. A binding condition may have developed from petroleum gum formation on the choke shaft or from damage. Choke shaft can usually be cleaned without disassembly by using Carbon X(X55) or equivalent. TR U C K SUP P - S E R VIC E 6 M -1 2 ENG INE FUEL 1. Remove air cleaner and disconnect choke rod upper lever. 2. Remove bolt attaching choke coil to head, and remove choke coil and choke rod as an assembly. 3. Disconnect choke rod from choke coil. 4. Connect choke rod to new choke coil and install assembly on manifold. 5. Install bolt and tighten securely. 6. Adjust and connect choke rod as outlined. 7. Start and warm-up engine, then check operation of choke and install air cleaner. AIR HORN TIGHTENING SEQUENCE Refer to Figure 18 for proper air horn tightening sequence. F ig . 1 8 - A ir H o rn T ig h te n in g S e q u e n c e TRUC K S U P P - S ER VIC E E NG IN E FUEL 6 M -1 3 D IAG NO SIS G EN E R A L 5. Engine com pression. When carburetor troubles are encountered they can usually be diagnosed and corrected w ith an adjustm ent as outlined below and under M aintenance and A djustm ents. 6. Ignition system firing voltage. 7. Ignition spark tim ing. Before diagnosing the c arburetor as the trouble area, check and diagnose the follow ing: 8. Spark plugs 1. Fuel Supply 9. Secure intake m anifold. 2. Fuel pum p pressure and volume. 10. Engine tem perature. 3. Plugged fuel filter or fuel lines. Use the follow ing tables to diagnose carburetor 4. Linkage and emission control systems. P r o b le m : e n g in e id l e s r o u g h a n d s t a l l s Re-set Id le speed s e ttin g . lo w and c u rb idle speeds u n d e r m a in te n a n ce and a d ju stm en ts. M a n ifo ld va c u u m hoses d is c o n n e c te d or im p r o p e rly in ­ s ta lle d . C h e ck a ll va c u u m c a rb u re to r base fo r hoses le ad ing in to th e m a n ifo ld leaks o r be in g d is c o n n e c te d . or In s ta ll o r re place as necessary. C a rb u re to r loose o n in ta k e m a n ifo ld . T o rq u e In ta k e m a n ifo ld is loose o r gaskets are d e fe c tiv e . U sing a pressure o il can, s p ra y lig h t o il o r ke rosene a ro u n d c a rb u re to r to m a n ifo ld m a n ifo ld legs and c a rb u re to r base. b o lts (1 0 -1 4 ft. lbs.). I f en g in e R P M changes, tig h te n o r re place th e m a n ifo ld gaskets o r c a rb u re to r base gaskets as necessary. H o t id le c o m p e n s a to r n o t o p e ra tin g (w h e re used.) N o rm a lly th e h o t id le c o m p e n s a to r s h o u ld be closed w h e n e n gine is ru n n in g c o ld and o p e n w h e n en g in e is h o t (a p p ro x . 1 4 0 ° F a t c o m p .) re p la ce if d e fe c tiv e . C a rb u re to r flo o d in g . N O T E : A ls o check c a rb u re to r flo o d in g w h e n engine cranks (tu rn ove r) b u t w ill n o t s ta rt o r s ta rts hard w hen co ld . 1. R em ove a ir h o rn and check flo a t a d ju s tm e n t, as spe cifie d in c a rb u re to r ove rh a u l sectio n. 2. C heck flo a t ne edle and seat fo r p ro p e r seal. I f a needle and seat te s te r is n o t a va ila b le , m o u th s u c tio n can be a p p lie d to th e n e edle seat w ith ne edle in s ta lle d . I f th e needle is d e fe c tiv e , re place w ith a fa c t o r y m a tc h e d set. 3. C heck f lo a t fo r be in g load ed w it h fu e l, b e n t flo a t hanger o r b in d s in th e flo a t arm . NOTE: A s o lid f lo a t can be ch e cke d f o r fu e l a b s o rp tio n b y lig h tly squ eezing b e tw e e n fin g e rs. I f w etness appears on su rfa ce o r flo a t fee ls he avy (ch e ck w ith k n o w n g o od flo a t) , re place th e f lo a t a sse m bly. 4. I f excessive d i r t fu e l system and is fo u n d in th e c a r b u re to r, clean th e c a rb u re to r. R epla ce fu e l filte r as necessary. TRUC K SUP P - SER VICE 6 M -1 4 ENG IN E FUEL P ro b le m : ENGINE CRANKS (TURNS OVER) BUT WILL NOT START OR STARTS HARD WHEN COLD. C O R R E C TIVE A C TIO N POSSIBLE CAUSE Im p ro p e r s ta rtin g p ro c e d u re used. Check p ro p e r s ta rtin g , as o u tlin e d in th e o w n e r's m anual. N o fu e l in gas ta n k A d d fu e l. C heck fu e l gauge fo r p ro p e r o p e ra tio n . C h o k e valve n o t c lo s in g s u ffic ie n tly w h e n c o ld . A d ju s t th e ch o ke c o il ro d. C h o k e valve o r lin k a g e b in d in g o r s tic k in g . R ealig n th e c h o k e valve o r lin k a g e as necessary. by d ir t and g u m , clean w ith D o n o t o il c h o k e lin ka g e . a u to m a tic I f caused c h o k e cleaner. I f p a rts are re p la ce d , check a d ju s tm e n ts . N o fu e l in c a rb u re to r. 1. R em o ve fu e l lin e at c a rb u re to r. lin e and ru n C o n n e c t hose to fu e l in to m e ta l c o n ta in e r. R e m o ve th e high te n s io n c o il w ire fro m ce n te r to w e r o n d is tr ib u to r cap and g ro u n d . C ra n k over e n gine — i f th e re is no fu e l discha rge fro m th e fu e l lin e , che ck f o r k in k e d o r b e n t lines. D is c o n n e c t fu e l lin e a t ta n k and b lo w o u t w ith a ir hose, re c o n n e c t lin e and ch e ck again f o r fu e l d is ­ charge. I f n o ne, re place fu e l p u m p . C heck p u m p fo r ad e q u a te flo w , as o u tlin e d in service m a n u a l. 2. I f fu e l s u p p ly is o .k ., che ck th e fo llo w in g : a. Inspect fu e l filte r . If plugged replace. b. If f ilt e r is o .k ., rem ove a ir h o rn and check fo r a b in d in th e flo a t m echanism o r a s tic k in g flo a t needle. If o .k ., a d ju st flo a t as spe cifie d in c a rb u re to r ove rhau l sectio n. E ngine F lo o d e d . N O TE: To check C heck p ro p e r c a rb u re to r u n lo a d in g p ro ce d u re . Depress th e fo r flo o d in g , w ith th e engine o f f , and Fuel w ill w ill be be v e ry d rip p in g o ff lo o k rem ove th e a ir cleaner, in to th e c a rb u re to r bore. no zzle a n d /o r th e c a rb u re to r a c ce le ra to r to te rm in e th e flo o r and che ck th e c a rb u re to r to de­ i f th e ch o ke valve is op e n in g . If n o t, a d ju s t th e t h r o ttle linkag e and u n lo a d e r, as sp e cifie d . w e t. C a rb u re to r flo o d in g NOTE: B e fo re re m o v in g th e c a rb u re to r a ir h o rn , use th e fo llo w in g p ro c e d u re w h ic h m ay e lim in a te th e flo o d in g . 1. R em o ve th e fu e l lin e a t th e c a rb u re to r an d plug . C ra n k and ru n th e e n g in e u n til th e fu e l b o w l ru ns d ry . o f f th e e n gine and c o n n e c t fu e l lin e . ru n engine. T u rn T h e n re -s ta rt and T h is w ill u s u a lly flu s h d ir t past th e c a rb u ­ re to r f lo a t ne edle and seat. 2. I f d ir t is in fu e l system , clean th e system and re place fu e l f ilt e r as necessary. m ove th e c a rb u re to r u n it. I f excessive d ir t is fo u n d , re­ D isassem ble and clean. 3. C heck flo a t needle and seat f o r p ro p e r seal. I f a needle and seat te ste r is n o t a va ila b le , a p p ly m o u th s u c tio n to th e ne edle seat w ith ne edle in s ta lle d . I f th e needle is d e fe c tiv e , re place w ith a fa c to r y m a tch e d set. 4. C heck flo a t fo r being loaded w it h fu e l, b e n t flo a t hanger o r b in d s in th e flo a t arm . N O T E : C heck flo a t fo r fu e l a b s o rp tio n b y lig h tly squeezing betw een fing ers. If w etness appears on surface o r flo a t feels heavy (Check w ith know n good flo a t) , replace th e flo a t assem bly. 5. A d ju s t flo a t as spe cifie d in c a rb u re to r o ve rhau l sectio n. T R U C K SUP P - ENG IN E FUEL 6 M -1 5 Problem: ENGINE STARTS AND STALLS Engine does n o t have enough fast idle speed w hen cold. C heck a n d re-set th e fa s t id le s e ttin g an d fa s t id le cam . C h o k e v acu um b reak u n it is n o t a d ju s te d to s p e c ific a tio n 1. A d ju s t va cu u m b reak t o s p e c ific a tio n . o r u n it is d e fe c tiv e . 2. I f a d ju ste d O .K ., che ck th e v a c u u m bre a k fo r p ro p e r o p e ra tio n as fo llo w s : O n th e e x te rn a lly m o u n te d va c u u m b reak u n it , c o n n e c t a p iece o f hose to th e n ip p le o n th e v a c u u m b re a k u n it and a p p ly s u c tio n a p p ly va cu u m . v a cu u m . N OTE: by m o u th or use to o l 1-23418 to < P lu n g e r s h o u ld m o ve in w a rd and h o ld If n o t, re p la ce th e u n it. A lw a y s c h e ck th e fa st id le cam a d ju s tm e n t b e fo re a d ju s tin g va cu u m bre a k u n it. C h o k e c o il ro d o u t o f a d ju s tm e n t. A d ju s t c h o k e c o il ro d . C h o k e valve a n d /o r lin k a g e s tic k in g o r b in d in g . 1. Clean and a lig n c h o k e valve and lin ka g e . R eplace if necessary. 2. R e-a djust if p a rt re p la c e m e n t is necessary. A d ju s t lo w and c u rb id le speeds to s p e c ific a tio n s on label in Id le speed s e ttin g engine c o m p a rtm e n t. N o t en ough fu e l in c a rb u re to r. 1. C heck fu e l p u m p pressure and v o lu m e . 2. C heck fo r p a r tia lly p lug ged fu e l in le t filte r . R epla ce if d ir t y . 3. R em ove a ir h o rn and che ck flo a t a d ju s tm e n ts as spe cifie d S in c a rb u re to r o ve rh a u l sectio n. 1. C heck f lo a t ne edle and seat f o r p ro p e r seal. C a rb u re to r flo o d in g . I f a needle N O T E : A ls o check c a rb u re to r flo o d in g w h e n engine cranks and seat te s te r is n o t a va ila b le , m o u th s u c tio n can be (tu rn a p p lie d over) b u t w ill n o t s ta rt o r starts hard w h e n c o ld . to th e needle seat w ith ne edle in s ta lle d . If needle is d e fe c tiv e , re place w ith a fa c to r y m a tc h e d set. 2. C heck flo a t f o r be in g loa d e d w ith fu e l, b e n t flo a t hanger o r b in d s in th e flo a t a rm . N O T E : Check flo a t fo r fu e l a b s o rp tio n b y lig h tly squeezing betw een fing ers. I f w etness appears on surface o r flo a t feels heavy (check w ith know n good flo a t), replace th e flo a t assem bly. 3. Check flo a t a d ju s tm e n ts as sp e cifie d in c a rb u re to r o v e r­ haul se ctio n . 4. If excessive d ir t is fo u n d in th e c a rb u re to r, clean the fu e l system and c a rb u re to r. R eplace fu e l f ilt e r as necessary. i TRUC K SUP P - SI 6 E N G IN E FUEL P r o b le m : e n g in e r u n s u n e v e n o r s u r g e s POSSIBLE CAUSE C O R R E C T IV E A C T IO N F u el R e s tric tio n C heck all hoses and fu e l lines fo r be nds, k in k s o r leaks. S tra ig h te n and secure in p o s itio n . C heck all fu e l filte r s . D ir t o r w a te r in fu e l system . I f p lug ged o r d ir t y - replace. C lean fu e l ta n k and lines. Fuel level A d ju s t flo a t as spe cifie d R em o ve and clean c a rb u re to r. in c a rb u re to r o ve rh a u l section. Check fo r fre e flo a t and flo a t needle valve o p e ra tio n . M a in m e te rin g je t d e fe c tiv e , loose o r in c o rre c t p a rt. Replace as necessary. Pow er system in c a rb u re to r n o t fu n c tio n in g p ro p e rly . P ow er Free u p o r re place as necessary. valve s tic k in g in d o w n p o s itio n . V a c u u m leakage It is a b s o lu te ly necessary th a t all v a c u u m hoses and gaskets are p ro p e r ly in s ta lle d , w ith no a ir leaks. T h e c a rb u re to r and m a n ifo ld s h o u ld be e v e n ly tig h te n e d to sp e cifie d to rq u e . Pro b lem : po o r f u e l e c o n o m y C heck en g in e c o m p re s s io n . E n g in e needs c o m p le te tu n e -u p . E x a m in e spa rk p lug s, ( if d ir t y o r im p r o p e rly ga pped , clean and re-gap o r re place). C heck ig n itio n p o in t d w e ll, c o n d itio n , re a d ju s t ig n itio n p o in ts if necessary and che ck an d reset ig n itio n tim in g . re place a ir cle a n e r e le m e n t if d ir t y . C lean o r C heck fo r re s tric te d e xh a u st system and in ta k e m a n ifo ld f o r leakage, m a ke sure a ll va cu u m hoses are c o n n e c te d c o r re c tly . 1. C lean c h o k e an d fre e u p linkag e. C h o k e valve n o t f u l l y o p e n in g . 2. Check ch o ke co il ro d fo r p ro p e r a d ju s tm e n t. Reset to sp e cifica tio n s. F u e l leaks. C heck fu e l ta n k , fu e l lines and fu e l p u m p fo r a n y fu e l leakage. Pow er system in c a rb u re to r n o t fu n c tio n in g p ro p e rly . P ow er Free u p o r re place as necessary. valve s tic k in g in up p o s itio n . H ig h fu e l level in c a rb u re to r o r c a rb u re to r flo o d in g . 1. C heck fo r d ir t in th e needle and seat. T e st u sin g s u c tio n b y m o u th o r needle seat te s te r. I f d e fe c tiv e , replace needle and seat asse m bly w ith fa c to r y m a tc h e d set. 2. C heck f o r load ed flo a t. 3. Re-set c a rb u re to r flo a t as sp e cifie d in c a rb u re to r o ve rh a u l sectio n. 4. I f excessive d i r t is present in th e c a r b u re to r b o w l, th e c a rb u re to r s h o u ld be cleaned. Fuel be in g p u lle d fr o m a c c e le ra to r system in to v e n tu ri th ro u g h p u m p je t. R u n en gine a t R P M w h e re n o z z le is fe e d in g fu e l. p u m p je t. O bserve I f fu e l is fe e d in g fr o m je t, ch e c k p u m p discha rge b a ll f o r p ro p e r seating b y fillin g c a v ity ab o ve b a ll w ith fu e l to level o f casting. N o "le a k d o w n " s h o u ld o c c u r w ith d ischa rge b a ll in place. R e-stake o r re place le a k in g che ck b a ll, d e fe c tiv e s p rin g , o r re ta in e r. A ir bleeds o r fu e l passages in c a rb u re to r d i r t y o r plugged. C lean c a rb u re to r o r o v e rh a u l as necessary. TR U C K SUPP - SER VIC E ENG INE FUEL 6 M -1 7 P r o b le m : e n g in e h e s it a t e s o n a c c e l e r a t io n 1. R e m o ve a ir D e fe c tiv e a c c e le ra to r p u m p system NOTE: A q u ic k c h e c k o f th e p u m p system can be m ade as fo llo w s . W ith th e en g in e o f f , re m o v e a ir cle a n e r and lo o k h o rn and ch e ck 2. C heck th e pum p disch a rg e in to th e c a rb u re to r b o res and ob serve p u m p s tre a m , w h ile lo c a tio n . b r is k ly o p e n in g t h r o t t le valve. n e x t to th e p u m p w e ll. e m it fr o m pum p je t an d A f u ll stre am o f fu e l s h o u ld s trik e near th e c e n te r o f th e I f cra c k e d , b a ll fo r p ro p e r seating ar T h e p u m p discha rge b a ll is lo c a te d in a c a v ity T o ch e ck f o r p ro p e r seating, re m o ve a ir h o rn and gasket a n d f i l l c a v ity w ith fu e l. N o "le a k d o w n " s h o u ld o c c u r. v e n tu ri area. p u m p cu p . scored o r d is to rte d , re place th e p u m p p lu n g e r. b a ll if le a kin g . R esta ke and re p la ce che ck M a ke sure d ischa rge b a ll, s p rin g , and re­ ta in e r are p r o p e r ly in s ta lle d . D ir t in p u m p passages o r p u m p je t. C lean and B lo w o u t w ith com pressed a ir. F u el level. Check fo r s tic k in g flo a t needle o r b in d in g flo a t. Free up o r replace p a rts as necessary. C heck and reset flo a t level as spe cifie d in c a rb u re to r o ve rh a u l sectio n. L e a k in g a ir h o rn to f lo a t b o w l gasket. T o rq u e a ir h o rn to flo a t bowl using p ro p e r tig h te n in g p ro ce d u re . C a rb u re to r loose o n m a n ifo ld . , - # T o rq u e c a rb u re to r t o m a n ifo ld b o lts . NO POWER ON HEAVY ACCELERATION P ro b le m : o r a t h ig h s p e e d C a rb u re to r t h r o t t le valve n o t g o in g w id e o p e n . (C heck A d ju s t t h r o t t le lin k a g e to o b ta in w id e o p e n t h r o t t le b y p u s h in g a c c e le ra to r pedal to flo o r ) . c a rb u re to r. D ir ty R eplace w it h a ne w f i l t e r e le m e n t. o r plugged fu e l (1 0 -1 4 f t . lbs.). filte r . in P ow er system n o t o p e ra tin g . C heck p o w e r valve fo r fre e up and d o w n m o v e m e n t. F lo a t level to o lo w . 1. C heck and reset flo a t level as specified in c a rb u re to r o ve r­ F lo a t n o t d ro p p in g fa r e n o u g h in to flo a t b o w l. C heck f o r b in d in g flo a t hanger and f o r p ro p e r flo a t a lig n ­ haul se ctio n . m e n t in flo a t b o w l. M a in m e te rin g je t d ir t y , plug ged o r in c o rre c t p a rt. 1. If the m ain m e tering je t is plugged or d ir t y and excessive d ir t is in fu e l b o w l, c a rb u re to r sho uld be c o m p le te ly dis­ assembled and cleaned. P ro b le m : e n g in e s t a r t s h a r d w h e n h o t C h o k e valve n o t o p e n in g c o m p le te ly . 1. C heck f o r b in d in g c h o k e valve a n d /o r lin ka g e . Clean and fre e -u p o r replace p a rts as necessary. D o n o t o il c h o k e linkage. 2. C heck and a d ju st cho ke c o il rod. E n g in e flo o d e d - C a rb u re to r flo o d in g . See p ro c e d u re u n d e r "E n g in e cra nks, w ill n o t s ta r t" . N o fu e l in c a rb u re to r. 1. C heck fu e l p u m p . R un pressure and v o lu m e test. 2. C heck flo a t needle f o r s tic k in g in seat, o r b in d in g flo a t. Le a k in g flo a t b o w l. F ill b o w l w ith fu e l and lo o k fo r leaks. -------------------------------------- 1 _______________________________________ / TR U C K SUP P - SER VIC E 6 M -1 8 ENG INE FUEL 2GC CARBURETOR General D escription......................................................... 6M-18 Theory of Operation........................................................ 6M-19 Float System ................................................................... 6M-19 Idle System ......................................................................6M-19 Main Metering System..................................................6M-20 Power Enrichment System...........................................6M-20 Pum p System.................................................................. 6M-21 M aintenance and A djustm ent....................................... 6M-22 Idle Speed A djustm ent................................................. 6M-22 Idle M ixture.................................................................... 6M-22 Idle M ixture A djustm ent...........................................6M-22 Pump Rod A djustm ent................................................ 6M-22 Intermediate Choke Rod A djustm ent....................... 6M-22 Autom atic Choke Coil A d ju stm en t...........................6M-23 Fast Idle Cam A djustm ent..........................................6M-23 Vacuum Break A djustm ent..........................................6M-23 Choke Unloader A djustm ent...................................... 6M-24 Service Operations.............................................................6M-24 Carburetor Replacem ent............................................... 6M-24 Fuel Filter R eplacem ent.............................................. 6M-25 Air H orn Tightening Sequence...................................6M-25 D iagnosis.............................................................................6M-26 GENERAL DESCRIPTION The Model 2GC (Figs. 19 and 20) is equipped with an integral choke attached to the throttle body assembly. A large drilled hole in the air horn leads from inside the air horn bore to a vapor dome located in the air horn casting above the fuel in the float bowl. Vapor canister purge ports are located in the throttle body casting. The ports connect by a channel to a tube pressed into the throttle body casting which leads directly to the vapor canister. This provides adequate purge during engine operation to remove all fuel vapors from the vapor collection canister. The pump system has a raised cast in boss on the floor of the float bowl, which prevents entry of dirt into the accelerator pum p - power valve fuel inlet passage. The pump plunger head has an expander spring beneath the pump cup to maintain good pump wall contact during pump operation. The end of the pum p plunger stem is upset in manufacturing to provide the "clipless" retaining feature. The pump plunger assembly may be removed from the inner lever by twisting upset end with small pliers until it breaks. The service pump assembly has a grooved end and is provided with a retaining clip. Alphabetical code letters cast next to the vacuum and air tubes identify all hose connections. As mentioned, the code letters are alphabetical and should be referred to during carburetor installation on the engine. The carburetor part number is stamped on the flat section of the float bowl next to the fuel inlet nut. When servicing the carburetor unit, refer to the Adjustment section for proper procedures and specifications. T R U C K S U P P • S E R VIC E ENG INE FUEL 6 M -1 9 CLEAN AIR TUBE AIR HORN S' ACCELERATOR PUMP ROD FUEL INLET CHOKE CLOSING ASSIST. SPRING THROTTLE LEVER FAST IDLE CAM CHOKE HEAT INLET CHOKE BREAK DIAPHRAGM THERMOSTATIC COIL PURGE TUBE Fig. 1 9 -2 G C C a rb u re to r - Fro n t FULL SPARK PORT GAS RECIRCULATION VACUUM PORT Fig. 2 0 - 2 G C C a rb u re to r - 3 / 4 V ie w THEORY OF OPERATION FLOAT SYSTEM (Fig. 21) The float system controls the level of the fuel in the carburetor bowl. Fuel level is very im portant because it must be m aintained to give proper m etering through all operating ranges. As fuel is used from the carburetor bowl, the plastic float drops, moving the float needle off its seat allowing more fuel to enter the bowl, thereby keeping the fuel level constant. The fuel bowl is internally vented by a large drilled hole which leads from inside the air horn bore to a vapor dome above the fuel in the float bowl. The internal vent provides a balance in air pressure to m aintain constant air/fuel m ixture ratios. Also, the large internal hole vents fuel vapors that form during periods of hot engine operation for improved hot idle and restart. IDLE (LOW SPEED) SYSTEM (Fig. 22) The idle system is used to provide the proper m ixture ratios required during idle and low speed operation of the engine. The idle system consists of the idle tubes, idle passages, idle air bleeds, idle mixture needles, off-idle discharge ports and idle needle discharge holes. The idle m ixture needle discharge holes provide fuel for curb engine idle. As the throttle valve is opened further, the off-idle discharge ports are exposed to manifold vacuum. These ports supply additional fuel mixture for off-idle engine requirements. The fuel vapor collection canister is purged by ports located in the carburetor throttle body. Timed purge ports are connected from the carburetor bore to a common tube pressed into the throttle body casting. The tube connects directly to the vapor canister through a hose. Timed purge ports (one in each bore), located above the throttle valve near the off-idle discharge ports, purge the canister during off-idle and part throttle ranges of operation. An Exhaust G as Recirculation system is used to control oxides of nitrogen. A vacuum supply tube, located just beneath the spark tube on the float bowl, connects by a channel to purge ports located just above the throttle valve in the throttle body bore. As the throttle valve is opened beyond the idle position, the E.G.R. ports are exposed to manifold vacuum which supplies a signal to the diaphragm in the E.G .R. valve. The two ports located in the throttle body bore are timed to provide just the right am ount of vacuum to the E.G.R. valve diaphragm to control exhaust gases introduced into the intake manifold air/fuel mixtures. T R U C K SUP P - S E R VIC E 6 M -2 0 ENG INE FUEL E.G.R. (EXH A U ST GAS R ECIR CU LA TIO N ) TIMED CA N ISTER HOLE THROTTLE VALVE Fig. 2 2 —Id le (L o w S p e e d ) S ystem M A IN METERING SYSTEM (Fig. 23) As the throttle valves continue to open, the edge of the valves are gradually moving away from the wall of the carburetor bore, reducing the vacuum acting on the idle needle and off-idle discharge ports which gradually decreases fuel flow from the idle system. W ith the increased throttle opening, there is increased air velocity in the venturi system. This causes a drop in pressure in the large venturi which is increased many times in the small venturi. Since the low pressure (high vacuum) is now in the small venturi, fuel will flow in the following manner: Fuel from the float bowl passes through the main metering jets into the main wells and rises in the main well tubes. Plastic main well inserts are used in the main wells to provide smooth fuel flow for efficient metering. This results in improved fuel control in the off-idle, transfer, and part throttle range of operation. A ir entering the main wells through the main well air bleeds is mixed with fuel through calibrated holes in the main well tube. The mixture moves up and out of the main discharge nozzles into a mixture (high speed) passage where more air is added. The mixture then travels down through the m ixture passage to the small venturi where it is delivered to the air stream and on into the engine intake manifold. On some models, an additional fuel circuit, called "pull-over" enrichm ent (P.O.E.), has been provided which supplements the main metering system of the carburetor unit. In order to provide sufficient enrichm ent to the main metering system at higher air flows, two additional fuel feeds are located in the air horn just above the choke valve. They connect directly to the fuel in the float bowl, through channels which lead directly into a tube that extends into the fuel just above the main metering jets. A t approximately 8 pounds of air per minute and above, the extra fuel enrichment is added to supplement the main metering system. W ith the addition of the pull-over enrichm ent system, leaner mixtures can be m aintained during the part throttle or cruising ranges and extra fuel supplied at higher air flows to meet engine demands. POWER ENRICHM ENT SYSTEM (Fig. 24) The conventional vacuum sensitive power piston and power valve are used for power requirements. When manifold vacuum drops to a pre-determined point (called power cut-in), the power piston moves downward against spring tension to force the power valve plunger off its seat. Fuel then flows from the float bowl down past the valve plunger through a small calibrated orifice in the valve side and on into separate fuel channels leading to the power restrictions. The fuel passes through the power restrictions into the main fuel wells for desired enrichment at the main discharge nozzles. The power valve, located at the bottom of the fuel bowl, provides the correct fuel enrichment for power requirements. MANIFOLD VACUUM VACUUM RELIEF PASSAGE P U L L -O V E R E N R IC H M E N T FUEL FEED J FUEL PIC K U P TUBE -----M A IN NOZZLE M A IN M ETERING JET ---------------- PART THROTTLE A D J U S T M E N T SCREW Fig. 2 3 - M a i n M e te rin g S ystem POWER RESTRICTIONS MAIN WELL Fig. 2 4 - P o w e r E n ric h m e n t S ystem TR U C K S UPP - SER VIC E E NG INE FUEL 6 M -21 PUMP SYSTEM (Fig. 25) W hen the throttle valve is opened rapidly, air flow and manifold vacuum change almost instantly, while the heavier fuel tends to lag behind causing a m om entary leanness. The accelerator pum p system provides the fuel necessary for sm ooth operation on rapid acceleration. The therm ostatic coil in the choke housing is calibrated to hold the choke valve closed when the engine is cold. Fuel for acceleration is supplied by a double spring loaded pum p plunger. The top and bottom springs combine to move the plunger so that a smooth sustained charge of fuel is delivered for acceleration. Fuel is drawn into the pump well through the inlet check ball on the upw ard stroke of the pum p plunger. Downward motion of the pum p plunger, as on acceleration, seats the alum inum inlet check ball and forces the fuel through the pum p discharge passage where it unseats the pum p discharge ball and passes on through to the pump jets, where it sprays into the venturi area. An expander spring located beneath the pump cup ensures good contact between the lip of the pump cup and the pump well at all times. W hen the pum p is not in operation, the pump cup unseats from the plunger head and acts as a vent for the pump well. If vapors form in the pump well during hot operation, they are vented between the head and pump cup out into the fuel bowl. W ithout this pump vent, vapor pressure in the pump well might force fuel from the pump system into the engine manifold, causing hard starting when the engine is hot. The pump discharge ball in the accelerator pump passage prevents any pump pull-over or discharge of fuel from the pum p nozzles when the accelerator is inoperative. OPERATION OF CHOKE SYSTEM (Fig. 26) The model 2GC carburetor has an integral choke housing and therm ostatic coil assembly mounted on the carburetor throttle body. The choke system operates as follows: To close the choke valve, depress the accelerator pedal completely to allow the idle speed screw to clear the steps on the fast idle cam. A t this point, tension of the therm ostatic coil will rotate the choke valve to the closed position and the idle speed screw will come to rest on the highest step of the fast idle cam. During engine starting, the high vacuum beneath the choke valve causes extra fuel to flow from the carburetor ports providing a rich m ixture for quick engine starting. W hen the engine starts and is running, manifold vacuum is applied to the vacuum break diaphragm unit mounted on the carburetor air horn. The diaphragm unit, connected by linkage to the choke valve, opens the choke valve a predetermined am ount against coil tension so that the air/fuel mixture will be lean enough so the engine will run without loading or stalling. W hen the choke valve moves to the vacuum break position, the fast idle cam will drop from the high step to a lower step when the throttle is opened. The vacuum break unit is delayed in operation by an internal bleed check valve. The delay check valve slows down further opening of the valve a few seconds until the engine will run on slightly leaner mixtures. A choke closing assist spring is used on the vacuum diaphragm plunger stem. The spring assists in closing the choke valve, along with tension from the choke therm ostatic coil, for improved cold starting. The choke closing assist spring only exerts pressure on the vacuum break rod to assist in closing the choke valve during engine starting. W hen the engine starts and the choke vacuum diaphragm seats, the closing spring retainer hits a stop on the plunger stem and no longer exerts pressure on the vacuum break rod. A clean air purge feature is used on the vacuum break unit. The purpose of the clean air purge is to bleed air into the vacuum break passage and purge the system of any fuel vapors or dirt which might contam inate and plug the check valve located inside the diaphragm unit. The purge system TR U C K S U P P - S E R V IC E 6 M -2 2 ENG INE FUEL consists of a small bleed hole located in the end cover of the vacuum break diaphragm. A ball check is encased in the vacuum inlet tube. The ball seats when backfiring occurs to prevent contamination of filter. U nder norm al engine operation the ball is pulled off its seat by manifold vacuum. D uring engine operation, vacuum acting upon the diaphragm unit pulls a small am ount of filtered air through the bleed hole to purge the system. Engine vacuum supplied through an orifice in the choke housing pulls heat from the manifold heat stove into the housing and gradually relaxes coil tension which allows the choke valve to continue opening through inlet air pressure pushing on the off-set choke valve. The choke system is equipped with an unloader feature to partially open the choke valve should the engine become flooded or loaded. To unload the engine, the accelerator pedal must be depressed so that the throttle valves are held wide open. A tang on the throttle lever contacts the fast idle cam and through the choke rod forces the choke valve slightly open. This allows extra air to enter the carburetor bores and pass on into the engine manifold to lean out the fuel mixtures so the engine will start. MAINTENANCE AND ADJUSTMENT IDLE SPEED ADJUSTM ENT 1. W ith engine at normal operating tem perature, air cleaner on, choke open, and air conditioning OFF, connect a tachom eter to engine. 2. Set parking brake and block drive wheels. 3. Disconnect vacuum advance hose at distributor and plug hose. 4. Start engine, check timing and adjust as required. Reconnect vacuum advance hose. 5. W ith autom atic transmission in Drive or manual transmission in N eutral, turn idle speed screw to specified rpm. 6. Shut off engine and remove tachometer. 7. Remove blocks from drive wheels. IDLE MIXTURE The idle m ixture is factory preset and idle mixture screws are capped with plastic limiter caps. The cap permits screw to be turned about one turn leaner (clockwise) without breaking cap. The idle m ixture is set to achieve the smoothest idle while m aintaining emission levels within standards prescribed by Federal Law. A t major carburetor overhaul the idle mixture may be adjusted. Before suspecting idle m ixture as cause of poor idle quality, check ignition system, distributor, timing, air cleaner, PCV system, evaporation emission control and compression pressures. Also check all vacuum hoses and connections for leaks and check torques of carburetor attachm ent bolts. Adjustm ent is made using a tachometer. Idle Mixture Adjustment 1. W ith engine at norm al operating tem perature, air cleaner on, choke open, and air conditioning OFF, connect a tachom eter to engine. 2. Set parking brake and block drive wheels. 3. Disconnect vacuum advance hose at distributor and plug hose. 4. Start engine, check timing and adjust as required. Reconnect vacuum advances hose. 5. W ith engine at normal operating tem perature (not hot), air conditioning off, and air cleaner installed, position transmission selector in Drive (automatic transmission) or N eutral (manual transmission). 6. Break off tab on mixture cap using needle nose pliers. 7. Adjust idle rpm to the higher of the two idle speeds specified. (Example 6 5 0 /600). 8. Equally enrich (turn out) m ixture screws until maximum idle speed is achieved. Reset speed if necessary to the higher specified idle speed. 9. Equally lean (turn in) m ixture screws until the lower specified idle speed is achieved (Example 650/ 6 0 0 ). PUMP ROD ADJU STM EN T (Fig. 27) 1. Back out idle speed adjusting screw. 2. Hold throttle valve completely closed. 3. Gauge from top of air horn ring to top of pump rod. 4. If adjustm ent is required, bend rod. INTERMEDIATE CHOKE ROD ADJUSTM ENT (Fig. 28) 1. Remove therm ostatic cover coil, gasket, and inside baffle plate assembly by removing three attaching screws and retainers. 2. Place idle speed screw on the highest step of fast idle cam. 3. Close choke valve by pushing up on intermediate choke lever. TR U C K SUP P - S ER VIC E E NG INE FUEL 6 M -2 3 4. Tighten choke cover retaining screws. FAST IDLE CA M ADJU STM EN T (Fig. 30) 1. Turn idle speed screw in until it just contacts low step of fast idle cam. Then, turn screw in one full turn. 4. Edge of coil lever inside choke housing m ust line up with edge of plug gauge. 2. Place idle speed screw on second step of fast idle cam against highest step. 5. Bend intermediate choke rod at point shown to adjust. 3. Place gauge between upper edge of choke valve and wall of air horn. 6. Install therm ostatic coil and cover autom atic choke coil adjustment. 4. If adjustment is required, bend choke lever tang. referring to Fig. 3 0 - F a s t Id le C am A d ju s tm e n t A U TO M A TIC CHOKE COIL ADJUSTM ENT (Fig. 29) 1. Place idle speed screw on the highest step of fast idle cam. VACUU M BREAK ADJUSTM ENT (FIG. 31) 1. Seat the vacuum break diaphragm using an outside vacuum source. 2. Loosen therm ostatic choke coil cover retaining screws. 3. R otate choke cover against coil tension until choke valve begins to close. Continue rotating until index m ark lines up with specified point on choke housing. 2. Cover vacuum break bleed hole as shown using a small piece of tape, so that diaphragm unit will hold inward and not bleed down. T R U C K SUP P ■ S E R V IC E 6 M -2 4 ENG IN E FUEL 3. Place idle speed screw on high step of fast idle cam. CHOKE UNLOADER ADJUSTM ENT (Fig. 3 2 ) 4. Remove therm ostatic coil and cover and hold choke coil lever inside choke housing towards the closed choke position. 5. Gauge between upper edge of choke valve and air horn wall. 1. W ith throttle valves held in wide open position, place choke valve toward closed position. 2. Place specified gauge between upper edge of choke valve and air horn casting to check clearance. 3. If adjustment is required, bend tang on throttle lever. 6. Bend vacuum break rod at point shown to adjust. 7. After adjustm ent, remove piece of tape covering small bleed hole at rear of vacuum break diaphragm unit. Reconnect vacuum hose. 8. Install therm ostatic coil and cover autom atic choke coil adjustment. referring to © G A U G E BETW EEN UPPER E D G E OF C H O K E V A L V E A N D A IR H O R N C A S T IN G © G A U G E BETWEEN UPPER EDGE OF CHOKE VALVE A N D AIR HORN W ALL. © SEAT PLUNGER USING OUTSIDE V A C U U M SOURCE NOTE: PLUG PURGE HOLE W ITH A PIECE OF M A S KIN G TAPE NOTE: PLACE IDLE SPEED SCREW ON HIGH STEP OF FAST IDLE CAM © THROTTLE VA LVES W ID E O P E N I__ 2) HOLD TO W ARDS CLOSED CHOKE © BEND TAN NG TO A D J U S T Fig. 3 1 -V a c u u m B re a k A d ju s tm e n t Fig. 3 2 -C h o k e U n lo a d e r A d ju s tm e n t SERVICE OPERATIONS CARBURETOR REPLACEMENT (Fig. 33) Removal Flooding, stumble on acceleration and other performance complaints are, in m any instances, caused by presence of dirt, water, or other foreign m atter in carburetor. To aid in diagnosis, carburetor should be carefully removed from engine without draining fuel from bowl. Contents of fuel bowl may then be examined for contam ination as carburetor is disassembled. Check filter. 1. Remove air cleaner and gasket. 2. Disconnect fuel and vacuum lines from carburetor. 3. Disconnect fresh air hose and choke hose from choke system. 4. Disconnect accelerator linkage. 5. If equipped with autom atic transmission, disconnect detent cable. 6. Remove carburetor carburetor. attaching bolts and remove 7. Remove insulator. Installation It is good shop practice to fill carburetor bowl before installing carburetor. This reduces strain on starting m otor and battery and reduces the possibility of backfiring while attem pting to start engine. A small supply of fuel will enable carburetor to be filled and the operation of float and intake needle and seat to be checked. Operate throttle lever several times and check discharge from pum p jets before installing carburetor. 1. Clean throttle body and surfaces. intake manifold sealing 2. Install new insulator. TRUC K S U P P - S E R VIC E E NG INE FUEL 6 M -2 5 Fig. 3 4 - F u e l F ilte r R e p la c e m e n t AIR HORN TIGHTENING SEQUENCE 3. Position carburetor over intake manifold and install bolts. Tighten bolts simultaneously to 145 in. lbs. Refer to figure 35 for proper air horn tightening sequence. 4. Connect detent cable and adjust as required. 5. Connect accelerator linkage. 6. Connect fresh air hose and choke hose to choke system. 7. Connect fuel and vacuum lines. 8. Install air cleaner. 9. Refer to M aintenance and Adjustm ent and check idle speed. FUEL FILTER REPLACEMENT (Fig. 34) A plugged fuel filter will restrict fuel flow into carburetor and will result in a loss of engine power. 1. Disconnect fuel line connection at inlet fuel filter nut. 2. Remove inlet fuel filter nut from carburetor. 3. Remove filter element and spring. 4. Install element spring and filter element in carburetor. 5. Install new gasket on inlet fitting nut and install nut in carburetor and tighten securely. 6. Install fuel line and tighten connector. TRUC K S U P P - S E R VIC E 6 M -2 6 ENG INE FUEL DIAG NO SIS GENERAL 5. Engine com pression. When carburetor troubles are encountered they can usually be diagnosed and corrected w ith an adjustm ent as outlined below and under M aintenance and A djustm ents. 6. Ignition system firing voltage. 7. Ignition spark tim ing. Before diagnosing the carburetor as the trouble area, check and diagnose the following: 8. Spark plugs 1. Fuel Supply 9. Secure intake m anifold. 2. Fuel pum p pressure and volume. 10. Engine tem perature. 3. Plugged fuel filter or fuel lines. Use the follow ing tables to diagnose carburetor, 4. Linkage and emission control systems. P r o b l em : e n g in e id l e s r o u g h a n d s t a l l s Re-set Id le speed s e ttin g . lo w and c u rb id le speeds u n d e r m a in te n a n ce and a d ju stm e n ts. M a n ifo ld vacuum hoses d is c o n n e c te d or im p r o p e rly in ­ sta lle d . C heck a ll va cu u m c a r b u re to r base fo r hoses lead ing in to th e m a n ifo ld leaks o r be in g d is c o n n e c te d . or In s ta ll o r re place as necessary. C a rb u re to r loose o n in ta k e m a n ifo ld . T o rq u e In ta k e m a n ifo ld is loose o r gaskets are d e fe c tiv e . U sing a pressure o il can, s p ra y lig h t o il o r ke rosene a ro u n d c a rb u re to r to m a n ifo ld m a n ifo ld legs and c a rb u re to r base. b o lts (1 0 -1 4 ft. lbs.). I f en g in e R P M changes, tig h te n o r re p la ce th e m a n ifo ld gaskets o r c a rb u re to r base gaskets as necessary. H o t id le c o m p e n s a to r n o t o p e ra tin g (w h e re used.) N o rm a lly th e h o t id le c o m p e n s a to r s h o u ld be closed w h e n en gine is ru n n in g c o ld and o p e n w h e n e n g in e is h o t (a p p ro x . 1 4 0 ° ^ a t c o m p .) re place if d e fe c tiv e . C a rb u re to r flo o d in g . N O T E : A ls o che ck c a rb u re to r flo o d in g w h e n engine cranks (tu rn over) b u t w ill n o t s ta rt o r sta rts hard w hen co ld . 1. R em ove a ir h o rn and check flo a t a d ju s tm e n t, as spe cifie d in c a rb u re to r o ve rhau l sectio n. 2. C heck flo a t ne edle and seat fo r p ro p e r seal. I f a needle and seat te s te r is n o t a va ila b le , m o u th s u c tio n can be a p p lie d to th e n e edle seat w ith ne edle in s ta lle d . I f th e needle is d e fe c tiv e , re place w it h a fa c t o r y m a tc h e d set. 3. C heck f lo a t fo r be in g loaded w ith fu e l, b e n t flo a t hanger o r b in d s in th e f lo a t arm . NOTE: A s o lid f lo a t can be ch e cke d f o r fu e l a b s o rp tio n b y lig h tly squ eezing b e tw e e n fin g e rs. I f w etn ess appears on su rfa ce o r f lo a t fee ls he avy (ch e ck w it h k n o w n g o o d flo a t) , re place th e flo a t assem bly. 4. I f excessive d ir t is fo u n d in th e c a r b u re to r, clean th e fu e l system and c a rb u re to r. R e p la ce fu e l f ilt e r as necessary. TRUC K SUP P - SER VIC E E NG INE FUEL 6 M -2 7 P ro b le m : ENGINE CRANKS (TURNS OVER) BUT WILL NOT START OR STARTS HARD WHEN COLD. C O R R E C TIV E AC TIO N POSSIBLE CAUSE Im p ro p e r s ta rtin g p ro c e d u re used. C heck p ro p e r s ta rtin g , as o u tlin e d in th e o w n e r's m anual. N o fu e l in gas ta n k A d d fu e l. C heck fu e l gauge fo r p ro p e r o p e ra tio n . C h o k e valve n o t clo s in g s u ff ic ie n tly w h e n c o ld . A d ju s t th e ch o ke c o il ro d . R ealig n th e c h o k e valve o r lin k a g e as necessary. C h o k e valve o r lin k a g e b in d in g o r s tic k in g . by d ir t and g u m , clean w ith D o n o t o il c h o k e lin ka g e . a u to m a tic I f caused c h o k e cleaner. I f pa rts are re p la c e d , check a d ju s tm e n ts . 1. Insp ect ch o ke and va cu u m break fo r w o rn o r m issing In o p e ra tiv e ch o k e o r vacu um break. parts. Replace and a d ju s t as re q u ire d . 2. Insp ect ch o ke th e rm o s ta tic c o il fo r p ro p e r o p e ra tio n . Replace and a d ju st as re q u ire d . 1. R em o ve fu e l lin e a t c a rb u re to r. N o fu e l in c a rb u re to r. lin e and ru n in to C o n n e c t hose to fu e l m e ta l c o n ta in e r. R e m o ve th e high te n s io n c o il w ire fr o m c e n te r to w e r o n d is tr ib u to r cap and g ro u n d . C ra n k ove r en gine — if th e re is no fu e l discharge fro m th e fu e l lin e , che ck f o r k in k e d o r b e n t lines. D is c o n n e c t fu e l lin e a t ta n k and b lo w o u t w ith a ir hose, re c o n n e c t lin e and ch e ck again fo r fu e l d is ­ charge. I f n o n e , re p la ce fu e l p u m p . C h e ck p u m p fo r ad e q u a te flo w , as o u tlin e d in service m a n u a l. 2. If fu e l s u p p ly is o .k ., ch e ck th e fo llo w in g : a. Inspect fu e l filte r . If plugged replace. b. If f ilt e r is o .k ., rem ove a ir h o rn and check fo r a b in d in the flo a t m echanism o r a s tic k in g flo a t needle. If o .k ., a d ju s t flo a t as spe cifie d in c a rb u re to r o ve rhau l sectio n. C heck p ro p e r c a rb u re to r u n lo a d in g p ro c e d u re . Depress th e E ngine F lo o d e d . NOTE: To check engine and o ff fo r lo o k flo o d in g , in to rem ove a ir cleaner, w ith c a rb u re to r bore. Fuel w ill be a cce le ra to r to te rm in e th e flo o r and che ck th e c a rb u re to r to de­ if th e c h o k e valve is op e n in g . If n o t, a d ju s t th e d rip p in g o f f nozzle a n d /o r c a rb u re to r w ill be v ery w e t. th r o ttle linkag e and u n lo a d e r, as sp e cifie d . C a rb u re to r flo o d in g NOTE: B e fo re re m o v in g th e c a rb u re to r a ir h o rn , use th e fo llo w in g p ro c e d u re w h ic h m a y e lim in a te th e flo o d in g . 1. R em o ve th e fu e l lin e a t th e c a rb u re to r an d plu g . C ra n k and ru n th e e n g in e u n til th e fu e l b o w l ru n s d ry . o f f th e en g in e and c o n n e c t fu e l lin e . ru n engine. T u rn T h e n re -sta rt and T h is w ill u s u a lly flu s h d ir t past th e c a rb u ­ re to r flo a t n e edle and seat. 2. I f d ir t is in fu e l syste m , clean th e system and re p la ce fu e l f ilt e r as necessary. m o ve th e c a rb u re to r u n it. I f excessive d ir t is fo u n d , re­ D isassem ble and clean. 3. C heck flo a t n e edle and seat fo r p ro p e r seal. I f a needle and seat te ste r is n o t a va ila b le , a p p ly m o u th s u c tio n to th e needle seat w ith needle in sta lle d . I f th e needle is d e fe c tiv e , re p la ce w ith a fa c to r y m a tch e d set. 4. C heck flo a t fo r be in g load ed w ith fu e l, b e n t flo a t hanger o r b in d s in th e flo a t a rm . N O T E : C heck flo a t fo r fu e l a b s o rp tio n b y lig h tly squeezing betw een fing ers. I f w etness appears on surface o r flo a t feels heavy (C heck w ith know n good flo a t) , replace th e flo a t assem bly. 5. A d ju s t flo a t as spe cifie d in c a rb u re to r o ve rh a u l sectio n. TRUC K SUP P - S E R VIC E -28 ENG INE FUEL P ro b le m : e n g in e s t a r t s a n d s t a l l s Engine does no t have enough fast idle speed w hen cold. C heck and re-set th e fa st id le s e ttin g and fa st id le cam . C h o k e v a c u u m break u n it is n o t a d ju s te d to s p e c ific a tio n 1. A d ju s t va cu u m break to s p e c ific a tio n . o r u n it is d e fe c tiv e . 2. If a d ju ste d O .K ., che ck th e v a c u u m break fo r p ro p e r o p e ra tio n as fo llo w s : O n th e e x te rn a lly m o u n te d va cu u m b reak u n it, c o n n e c t a piece o f hose to th e n ip p le o n th e va cu u m break u n it and a p p ly s u c tio n a p p ly va cu u m . va cu u m . NOTE: by m o u th or use to o l J -2 3 4 1 8 to P lu n g e r s h o u ld m o ve in w a rd and h o ld I f n o t, re place th e u n it. A lw a y s ch e c k th e fa st id le cam a d ju s tm e n t b e fo re a d ju s tin g va cu u m break u n it. C h o k e c o il ro d o u t o f a d ju s tm e n t. A d ju s t c h o k e c o il ro d . C h o k e valve a n d /o r lin k a g e s tic k in g o r b in d in g . 1. Clean and a lig n c h o k e valve and lin ka g e . R eplace if necessary. 2. R e-a djust if p a rt re p la c e m e n t is necessary. Id le speed s e ttin g A d ju s t lo w and c u rb id le speeds to s p e c ific a tio n s on label in engine c o m p a rtm e n t. N o t en o u g h fu e l in c a rb u re to r. 1. C heck fu e l p u m p pressure and v o lu m e . 2. C heck fo r p a r tia lly plugged fu e l in le t filt e r . R epla ce if d ir t y . 3. R em ove a ir h o rn and check flo a t a d ju s tm e n ts as spe cifie d in c a rb u re to r ove rh a u l se ctio n . C a rb u re to r flo o d in g . 1. C heck flo a t ne edle and seat f o r p ro p e r seal. If a needle N O T E : A ls o check c a rb u re to r flo o d in g w h e n engine cranks and seat te s te r is n o t a va ila b le , m o u th s u c tio n can be (tu rn a p p lie d over) b u t w ill n o t s ta rt or starts hard w h e n c o ld . to th e needle seat w ith needle in s ta lle d . If needle is d e fe c tiv e , re place w ith a fa c t o r y m a tch e d set. 2. C heck flo a t f o r be in g load ed w it h fu e l, b e n t flo a t hanger o r b in d s in th e flo a t arm . N O T E : Check flo a t fo r fu e l a b s o rp tio n b y lig h tly squeezing betw een fingers. If w etness appears on surface o r flo a t feels heavy (check w ith know n good flo a t) , replace th e flo a t assem bly. 3. Check flo a t a d ju s tm e n ts as sp e cifie d in c a rb u re to r o v e r­ haul se ctio n . 4. If excessive d ir t is fo u n d in th e c a rb u re to r, clean th e fu e l system and c a rb u re to r. R eplace fue l f ilt e r as necessary. TR U C K S U P P - SER VIC E ENG IN E FUEL 6 M -2 9 P ro b le m : en g in e r u n s u n e v e n o r s u rg e s C O R R E C T IV E A C T IO N POSSIBLE CAUSE F uel R e s tric tio n C heck all hoses and fu e l lines fo r bends, k in k s o r leaks. S tra ig h te n and secure in p o s itio n . C heck all fu e l filte r s . D ir t o r w a te r in fu e l system . I f plug ged o r d ir t y - replace. C lean fu e l ta n k and lines. Fuel level A d ju s t flo a t as sp e cifie d R em o ve and clean c a rb u re to r. in c a rb u re to r ove rh a u l sectio n. Check fo r free flo a t and flo a t needle valve o p e ra tio n . M ain m e te rin g je t d e fe c tiv e , loose o r in c o rre c t p a rt. Replace as necessary. P ow er system in c a rb u re to r n o t fu n c tio n in g p ro p e rly . P ow er Free u p o r re place as necessary. valve s tic k in g in d o w n p o s itio n . V a c u u m leakage It is a b s o lu te ly necessary th a t a ll va cu u m hoses and gaskets are p ro p e r ly in s ta lle d , w ith no a ir leaks. T h e c a rb u re to r and m a n ifo ld s h o u ld be e v e n ly tig h te n e d to s p e cifie d to rq u e . P ro b lem : p o o r f u e l econo m y C heck en gine c o m p re s s io n . E n g in e needs c o m p le te tu n e -u p . E x a m in e spark plug s, ( if d ir t y o r im p r o p e rly ga pped , clean and re-gap o r re p la ce ). C heck ig n itio n p o in t d w e ll, c o n d itio n , re a d ju s t ig n itio n p o in ts if necessary and che ck an d reset ig n itio n tim in g . re place a ir cle a n e r e le m e n t if d ir t y . C lean o r C heck f o r re s tric te d e xh a u st system an d in ta k e m a n ifo ld fo r leakage, m a ke sure all va cu u m hoses are c o n n e c te d c o r re c tly . 1. C lean c h o k e an d fre e u p lin ka g e . C h o k e valve n o t f u l l y o p e n in g . 2. Check ch o ke c o il rod fo r p ro p e r a d ju s tm e n t. Reset to sp e cifica tio n s. C heck fu e l ta n k , fu e l F u e l leaks. lines and fu e l p u m p fo r a n y fu e l leakage. P ow er system in c a rb u re to r n o t fu n c tio n in g p ro p e rly . P ow er Free u p o r re p la ce as necessary. valve s tic k in g in up p o s itio n . H ig h fu e l level in c a rb u re to r o r c a rb u re to r flo o d in g . 1. C heck fo r d i r t in th e needle and seat. T e st using s u c tio n b y m o u th o r needle seat te s te r. If d e fe c tiv e , re place needle and seat a sse m bly w ith fa c to r y m a tch e d set. 2. C heck fo r load ed flo a t. 3. Re-set c a rb u re to r flo a t as spe cifie d in c a rb u re to r ove rh a u l sectio n. 4. I f excessive d i r t is pre se n t in th e c a rb u re to r b o w l, th e c a rb u re to r s h o u ld be cleaned. F u el be in g p u lle d fr o m a c c e le ra to r system in to v e n tu ri th r o u g h p u m p je t. R u n e n gine a t R P M w h e re n o z z le is fe e d in g fu e l. p u m p je t. O bserve I f fu e l is fe e d in g fr o m je t, ch e ck p u m p discharge b a ll fo r p ro p e r seating b y fillin g c a v ity a b o ve b a ll w ith fu e l to level o f castin g. N o "le a k d o w n " s h o u ld o c c u r w ith discha rge b a ll in place. R e-stake o r re p la ce le a k in g check b a ll, d e fe c tiv e s p rin g , o r re ta in e r. A ir bleeds o r fu e l passages in c a rb u re to r d ir t y o r plugged. C lean c a rb u re to r o r o v e rh a u l as necessary. T R U C K S UPP - S ER VIC E 6 M -3 0 ENG INE FUEL P ro b le m : e n g in e h e s it a t e s o n a c c e l e r a t i o n 1. R em o ve a ir D e fe c tiv e a c c e le ra to r p u m p system NOTE: A q u ic k c h e c k o f th e p u m p system can be m ade as fo llo w s . W ith th e en g in e o f f , re m o v e a ir cle a n e r and lo o k in to th e c a rb u re to r b o res and observe p u m p s tre a m , w h ile b r is k ly o p e n in g t h r o t t le valve. e m it fr o m p u m p je t an d A f u ll stream o f fu e l s h o u ld s trik e near th e c e n te r o f th e h o rn and che ck 2. C heck th e lo c a tio n . I f c ra c k e d , pum p d ischa rge b a ll fo r p ro p e r sea ting a r T h e p u m p d ischa rge b a ll is lo ca te d in a c a v ity n e x t to th e p u m p w e ll. T o ch e ck f o r p ro p e r seating, re m o ve a ir h o rn and gasket an d f i l l c a v ity w ith fu e l. N o "le a k d o w n ” s h o u ld o c c u r. v e n tu ri area. p u m p cu p . scored o r d is to rte d , re place th e p u m p p lu n g e r. b a ll if le a kin g . R esta ke and re p la ce che ck M a ke sure d ischa rge b a ll, s p rin g , an d re­ ta in e r are p r o p e r ly in s ta lle d . D ir t in p u m p passages o r p u m p je t. C lean and B lo w o u t w ith com pressed a ir. F u el level. C heck fo r s tic k in g flo a t needle o r b in d in g flo a t. Free up o r replace pa rts as necessary. C heck and reset flo a t level as spe cifie d in c a rb u re to r o ve rhau l sectio n. L e a k in g a ir h o rn to flo a t b o w l gasket. T o rq u e a ir h o rn to flo a t bowl using p ro p e r tig h te n in g p ro c e d u re . C a rb u re to r loose o n m a n ifo ld . D , - # T o rq u e c a rb u re to r to m a n ifo ld b o lts . NO POWER ON HEAVY ACCELERATION o r a t h ig h speed P ro b le m : C a rb u re to r t h r o t t le valve n o t g o in g w id e o p e n . (C heck A d ju s t t h r o t t le lin ka g e to o b ta in w id e o p e n t h r o t t le b y pu s h in g a c c e le ra to r pedal to flo o r ) . c a rb u re to r. D ir ty R eplace w ith a n e w f i l t e r ele m e n t. or plugged fue l (1 0 -1 4 f t . lbs.). filte r . in P ow er system n o t o p e ra tin g . C heck p o w e r valve fo r fre e up and d o w n m o v e m e n t. F lo a t level to o lo w . 1. Check and reset flo a t level as spe cifie d in c a rb u re to r o v e r­ F lo a t n o t d ro p p in g fa r e n o u g h in to flo a t b o w l. C heck fo r b in d in g flo a t hanger and f o r p ro p e r flo a t a lig n ­ haul sectio n. m e n t in f lo a t b o w l. M a in m e te rin g je t d ir t y , plugged o r in c o rre c t p a rt. 1. If the m ain m e te rin g je t is plugged o r d ir t y and excessive d ir t is in fu e l b o w l, c a rb u re to r sh o u ld be c o m p le te ly dis­ assembled and cleaned. P ro b le m : e n g in e s t a r t s h a r d w hen h o t C h o k e valve n o t o p e n in g c o m p le te ly . 1. C heck fo r b in d in g c h o k e valve a n d /o r lin ka g e . C lean and fre e -u p o r re place p a rts as necessary. D o n o t o il c h o k e linkage. 2. Check and a d ju st ch o ke c o il ro d. E ngine flo o d e d - C a rb u re to r flo o d in g . See p ro c e d u re u n d e r "E n g in e cra n ks, w ill n o t s ta r t" . N o fu e l in c a rb u re to r. 1. C heck fu e l p u m p . R u n pressure and v o lu m e test. 2. C heck flo a t needle fo r s tic k in g in seat, o r b in d in g flo a t. L e a k in g flo a t b o w l. F ill b o w l w it h fu e l and lo o k fo r leaks. TRUC K S U P P - S E R VIC E ENG IN E FUEL 6 M -3 1 M 4 M C /M 4 M E QUADRAJET CARBURETOR INDEX G eneral D escription..........................................................6M-31 Theory of O peration........................................................ 6M-32 Float System ....................................................................6M-32 Idle System ......................................................................6M-33 Exhaust Gas Recirculation...........................................6M-33 Canister Purge................................................................. 6M-34 M ain Metering System..................................................6M-34 Power System ................................................................. 6M-34 A ir Valve D ash p o t........................................................ 6M-36 Accelerating Pump System...........................................6M-37 Choke System ................................................................. 6M-37 Maintenance and A djustm ent....................................... 6M-40 Idle Speed A djustm ent..................................................6M-40 Idle M ixture.....................................................................6M-40 Idle M ixture A djustm ent............................................. 6M-40 Pum p Rod A djustm ent.................................................6M-41 Fast Idle A djustm ent....................................................6M-41 Choke Coil Lever A djustm ent.................................... 6M-41 Fast Idle Cam (Choke Rod) A djustm ent................6M41 Air Valve Dashpot A djustm ent..................................6M-42 Front Vacuum Break A djustm ent............................. 6M-42 Rear Vacuum Break A d ju stm en t.............................. 6M-42 A utom atic Choke Coil A d justm ent........................... 6M-43 Unloader A d ju stm en t....................................................6M-44 Secondary T hrottle Valve Lock-Out Adjustment.... 6M 44 Secondary Closing A d ju stm en t...................................6M-45 Secondary Opening A djustm ent..................................6M-45 Air Valve Spring W ind-Up A d justm ent.................. 6M-45 Throttle Lever A ctuator A djustm ent.........................6M 45 Service Operations.............................................................6M-46 Carburetor R eplacem ent............................................... 6M-46 Fuel Filter R eplacem ent.............................................. 6M 46 Air Horn Tightening Sequence...................................6M 46 Diagnosis.............................................................................6M 47 GENERAL DESCRIPTION The M 4M C-M 4M E model Quadrajet carburetors (fig. 36 and 36A) are two stage carburetors of downdraft design. The triple venturi system (with 1-7/32" venturi) is used on the prim ary side of the Quadrajet carburetor, with small 1-3/8" throttle valve bores. The triple venturi stack-up, plus small prim ary throttle valve bores, results in good fuel control during idle and part throttle operation. The secondary side has two large bores (2-1/4"). Using the air valve principle in the secondary side, fuel is metered in direct proportion to the air passing through the secondary bores. The carburetor part number is stamped on a vertical section of the float bowl, near the secondary throttle lever. Refer to the part number on the bowl when servicing the carburetor. W hen replacing the float bowl assembly, follow the m anufacturer’s instructions contained in the service package so that the part num ber can be transferred to the new float bowl. A throttle return control system with bracket, is used on some California light duty truck with heavy duty emissions and V8 engine. The vacuum unit and bracket assembly is mounted on the float bowl. W hen manifold vacuum is high, such as on deceleration, the vacuum diaphragm plunger moves outward, contacting the throttle lever, to open the primary throttle valves slightly to lean out the rich air/fuel mixture in the intake manifold. The throttle return control systems requires new adjustm ent procedures. Also refer to Section 6T, Emission Control System, for additional information. The prim ary side of the carburetor has six systems of operation. They are float, idle, main metering, power, pump, and choke. The secondary side has one metering system which supplements the prim ary main metering system and receives fuel from a common float chamber. TRUC K S U P P - S E R V IC E 6 M -3 2 ENG IN E FUEL Fig. 3 6 - M 4 M C Q u a d r a je t C a rb u re to r Fig. 3 6 A - M 4 M E Q u a d r a je t C a rb u re to r THEORY OF OPERATION FLOAT SYSTEM (Fig. 37) The float system operates in the following manner: Fuel from the engine fuel pum p enters the carburetor fuel inlet passage. It passes through the pleated paper filter element, fuel inlet valve, and on into the float bowl chamber. As the incoming fuel fills the float bowl to the prescribed level, the float pontoon rises and forces the fuel inlet valve closed, shutting off fuel flow. As fuel is used from the float bowl, the float drops allowing the float valve to open, when more fuel again fills the bowl. This cycle continues, maintaining a constant fuel level in the float bowl. A new float assembly is used for improved fuel handling in the float bowl. The float pontoon is solid and is made of a light weight closed cell plastic material. This feature gives added buoyancy to allow the use of a single float to maintain constant fuel levels. A float pull clip, fastened to the float valve, hooks over the edge of the float arm at the center rear. Its purpose is to assist in lifting the float valve off its seat whenever fuel level in the float bowl is low. CAUTION: Do not place pull clip through small holes in top o f float arm. Severe flooding will result. On some models, no side windows are used in the float valve seat so that all fuel will be discharged over the top of the float valve seat to control fuel turbulence in the float bowl. The carburetor float cham ber is internally vented by a vertical slot, cast in the air horn, located at the rear of the primary venturis, and by a pressed-in vent tube located in the air horn. The purpose of the vertical vent slot and vent tube is to balance air pressure acting on the fuel in the float bowl with air flow through the carburetor bores. In this way, balanced air/fuel ratios are maintained throughout all ranges of carburetor operation. Also, during periods of hot engine operation, the vents are used to relieve vapor pressures that build up in the float bowl, thereby preventing the pushing of raw fuel through the discharge nozzles into T R U C K S U P P - S ER VIC E E NG IN E FUEL 6 M -3 3 the engine to cause hard hot restarts. engine cylinders. An aneroid cavity insert is used in the float bowl. The insert is used to reduce fuel slosh in the float bowl. The idle mixture needles are adjusted at the factory to blend the correct am ount of fuel mixture from the idle system with the air entering the engine at idle. Turning the idle mixture needles inward (clockwise) decreases the idle fuel discharge and turning the mixture needles outward (counter­ clockwise) enriches the engine idle mixture. Idle mixture needles are adjusted at the factory and then limiter caps are installed to discourage idle mixture needle readjustment in the field. IDLE SYSTEM Each bore of the Quadrajet carburetor has a separate and independent idle system to supply the correct air/fuel mixture ratios during idle and off-idle operation. The idle system is used during this period because air flow through the carburetor venturi is not great enough to obtain efficient metering from the main discharge nozzles. M 4M C-M 4M E carburetor models have a fixed idle air bypass system. This consists of air channels which lead from the top of each carburetor bore in the air horn to a point below each throttle valve. A t normal idle, extra air passes through these channels supplementing the air passing by the slightly opened throttle valves. The purpose of the idle air bypass system is to allow reduction in the am ount of air going past the throttle valves so they can be nearly closed at idle. This reduces the am ount of air flowing through the carburetor venturi to prevent the main fuel nozzles from feeding during idle operation. The venturi system is very sensitive to air flow and where larger am ounts of idle air are needed to m aintain idle speed, the fixed idle air bypass system is used. The idle system operates as follows: D uring curb idle, the throttle valves are held slightly open by the idle speed screw. The small am ount of air passing between the throttle valves and bores is regulated by this screw to give the engine the desired idle speed. Since the engine requires very little air for idle and low speeds, fuel is added to the air to produce a combustible m ixture by the direct application of vacuum (low pressure) from the engine manifold to the idle discharge holes below the throttle valves. W ith the idle discharge holes in a very low pressure area and the fuel in the float bowl vented to atmosphere (high pressure), the idle system operates as follows: Fuel flows from the float bowl down through the main metering jets into the main fuel wells. It is picked up in the main wells by the two idle tubes (one for each bore) which extend into the wells. The fuel is m etered at the lower tip of each idle tube and passes up through the tube. The fuel is mixed with air at the top of each idle tube through an idle air bleed. Then the fuel m ixture crosses over to the idle down channels where it is mixed with air at the side idle bleed located just above the idle channel restriction. The m ixture continues down through the calibrated idle channel restrictions, past the lower idle air bleeds and off-idle discharge ports where it is further mixed with air. The air/fuel m ixture moves down to the idle mixture needle discharge holes where it enters the carburetor bores and blends with the air passing the slightly open throttle valves. The combustible air/fuel mixture then passes through the intake manifold to the As the primary throttle valves are opened from curb idle to increase engine speed, additional fuel is needed to combine with the extra air entering the engine. This is accomplished by the slotted off-idle discharge ports. As the primary throttle valves open they pass by the off-idle ports, gradually exposing them to high engine vacuum below the throttle valves. The additional fuel added from the off-idle ports mixes with the increasing air flow past the opening throttle valves to meet increased engine air and fuel demands. Further opening of the throttle valves increases the air velocity through the carburetor venturi sufficiently to cause low pressure at the lower idle air bleeds. As a result, fuel begins to discharge from the lower idle air bleed holes and continues to do so throughout operation of the part throttle to wide open throttle ranges, supplementing the main discharge nozzle delivery. EXHAUST GAS RECIRCULATION (E.G.R.) (Fig. 38) An Exhaust Gas Recirculation (E.G .R.) system is used on light duty emission vehicles and California heavy duty emission vehicle with 454 V8 engine to control oxides of nitrogen (NOx) emissions. The E.G.R. valve is operated by a vacuum signal taken from the carburetor. Two punched ports, one located just above the throttle valve and the other near the upper edge of the throttle body casting, provide a timed vacuum signal port for E.G .R. valve operation in the off-idle and part throttle ranges of the carburetor. The purpose of the E.G .R. system is to supply a metered am ount of exhaust gases to the combustion mixtures and lower combustion temperatures, thereby reducing oxides of nitrogen during these ranges of engine operation. The port system operates as follows: TR U C K S U P P - SER VIC E 6 M -3 4 ENG INE FUEL As the throttle valve is opened beyond the idle position, the first vacuum port for the E.G .R. system is exposed to manifold vacuum to supply a vacuum signal to the E.G.R. valve. To control the vacuum signal at the lower port, the upper port bleeds air into the vacuum channel and modulates the am ount of vacuum signal supplied by the lower E.G.R. port. In this m anner, the E.G .R. valve can be timed for precise metering of exhaust gases to the intake manifold, dependent upon location of the ports in the carburetor bore and degree of throttle valve opening. As the throttle valves are opened further in the part throttle range, the upper port ceases to function as an air bleed and is gradually exposed to manifold vacuum to supplement the vacuum signal at the lower port and maintain correct E.G.R. valve position. The upper and lower vacuum ports connect to a cavity in the throttle body which, in turn, through a passage, supply the vacuum signal to an E.G .R. tube pressed into the front corner of the throttle body casting. The tube in the throttle body is connected by a hose to the E.G .R. valve located on the intake manifold. The E.G .R. valve remains closed during periods of engine idle and deceleration to prevent rough idle, which could be caused from excessive exhaust gas contamination in the idle air/fuel mixtures. CANISTER PURGE (Fig. 38) In that the fuel tank is not vented to atm osphere and fuel vapors are collected in the vapor canister, a purge port is provided in the carburetor throttle body. The purge port leads through passages to a common cham ber in the throttle body to a purge tube which connects by a hose to the vapor canister. The purge port consists of a separate timed canister purge. Timed Bleed Purge The timed bleed purge port is located in each bore next to the off-idle discharge ports. The timed purge operates during off-idle, part throttle, and wide open throttle operation. This provides a larger purge capacity for the vapor canister and prevents over-rich m ixtures from being added to the carburetor metering at any time. M A IN METERING SYSTEM (Fig. 39) The main metering system supplies fuel to the engine from off-idle to wide open throttle. The prim ary bores (two smaller bores) supply air and fuel during this range. Separate main wells feed each fuel nozzle to improve fuel flow in the venture system. As the prim ary throttle valves are opened beyond the off-idle range allowing more air to enter the engine intake manifold, air velocity increases in the carburetor venturi to cause the main metering system to operate as follows: Fuel from the float bowl flows between the main metering rods and jets into the main fuel wells. It passes upward in the main well and is bled with air by an air bleed located at the top of the well. The fuel is further bled air through calibrated air bleeds located near the top of the well in the carburetor bores. The fuel m ixture then passes from the main well through the main discharge nozzles into the boost venturi. A t the boost venturi, the fuel m ixture then combines with the air entering the engine through the carburetor bores. It then passes as a combustible mixture through the intake manifold and on into the engine cylinders. The main metering system is calibrated by tapered and stepped metering rods operating in metering jets and also through the main well air bleeds. D uring cruising speeds and light engine loads, manifold vacuum is high. In this period, the engine will run on leaner mixtures than required during heavy loads. The primary main metering rods are connected to a vacuum responsive piston which operates against spring tension. Engine manifold vacuum is supplied to a power piston through a vacuum channel. W hen the vacuum is high, the piston is held downward against spring tension and the larger diameter of the metering rod is in the main metering jet orifice. This results in leaner fuel mixtures for economy operation. As engine load increases and engine manifold vacuum drops, spring pressure acting on the power piston overcomes the vacuum pull and gradually lifts the metering rods partially out of the main metering jets. This enrichens the fuel mixture enough to give the desired power to overcome the added load. Adjustable Part Throttle In order to provide a close tolerance adjustm ent in the main metering system, an adjustm ent is provided to very accurately set the depth of the metering rods in the main metering jets. The adjustment consists of a pin pressed in the side of the power piston which extends through a slot in the side of the piston well. W hen the power piston is down (economy position), the side of the pin stops on top of a flat surface on the adjustm ent screw located in the cavity next to the power piston. The adjustm ent screw is held from turning by a tension spring beneath the head of the adjustment screw. During production flow test, the adjustm ent screw is turned up or down which in turn raises or lowers the power piston and metering rod assembly. This very accurately controls the fuel flow between the rods and jets to meet emission requirements. CAUTION: No attempt should be made to change the A.P. T. adjustment in the field. I f float bowl replacement is required, the new bowl assembly will include an adjustment screw pre-set by the factory. POWER SYSTEM (Fig. 40) The power system provides extra mixture enrichment for heavy acceleration or high speed operation. The richer mixture is supplied through the main metering system in the primary and secondary sides of the carburetor. The power system located in the prim ary side consists of a vacuum piston and spring located in a cylinder connected by a passage to intake manifold vacuum. The spring located beneath the vacuum operated power piston tends to push the piston upward against manifold vacuum. TRUC K SUP P ■ SER VICE E NG INE FUEL 6 M -3 5 M A IN WELL AIR BLEEDS BOOST VENTURI FACTORY-METERING ADJUSTMENT SCREW X NOTE: SIDE FUEL ENTRY M A IN VENTURI THROTTLE VALVE M A IN POWER PISTON (D O W N ) POWER PISTON SPRING VACUUM PASSAGE JJ^IN METERING JETS (2) M A IN METERING RODS (2 ) F ig . 3 9 - M a in M e te rin g S y s te m A n adjustable part throttle allows each carburetor to be individually calibrated at time of assembly. Each carburetor is adjusted by the m anufacturer to provide the most ideal air/fuel ratio for low exhaust emissions. The adjustable part throttle screw is used to raise or lower the power piston and metering rods to provide this ratio. In part throttle and cruising ranges, manifold vacuum is sufficient to hold the power piston down against spring tension so that the larger diam eter of the metering rod is held in the main metering jet orifice. M ixture enrichm ent is not necessary at this point. However, as engine load is increased to a point where extra fuel enrichm ent is required, the spring tension overcomes the vacuum pull on the power piston and the tapered primary metering rod moves upward in the main metering jet orifice. The smaller diam eter of the metering rod allows more fuel to pass through the main metering jet and enrich the m ixture flowing into the prim ary main wells and out the main discharge nozzles. W hen manifold vacuum rises and m ixture enrichment is no longer needed, the vacuum overcomes the power piston spring tension and returns the larger portion of the metering rod into the metering jet orifice and back to normal economy ranges. As the engine speed increases, the prim ary side of the carburetor can no longer meet the engine air and fuel requirements. To meet these demands, the secondary side of the carburetor is used. As the secondary throttle valves are opened, engine manifold vacuum (low pressure) is applied directly beneath the air valves. Atm ospheric pressure on top of the air valves forces the air valves to open against spring tension and allows metered air to pass through the secondary bores of the carburetor. When the secondary throttle valves begin to open, the accelerating well ports are exposed to manifold vacuum. The ports immediately start to feed fuel from the accelerating wells and continue to feed fuel until the fuel in the well is gone. This prevents a momentary leanness as the air valve opens and before the secondary nozzles begin to feed fuel. TR U C K SUP P • S E R V IC E 6 M -3 6 ENG INE FUEL SECONDARY M E T E R IN G R O D S ( 2 ) BOOST VENTURI ACCELERATO R W ELL & TU B E F A C T O R Y -M E T E R IN G ADJUSTM ENT SCREW A IR VALVE M E T E R IN G R O D LEVER NOTE: SIDE FUEL ENTRY ! THROTTLE LEVER A C TU A fO R TO AIR aEr SPARK ^ ER TO A IR " CLEANER DIVERTER VALVE CK10, 20, 3 0 = ^ 350/400-V 8 CAL. P20 & 30 350-V 8 CAL THROTTLE RETURN CONTROL VALVE DIVERTER VALVE ./ / '. THROTTLE RETURN CONTROL VALVE Fig. 3 -E m is s io n H ose R ou tin gs - CKP T R U C K SUP P - SER VIC E 6T-4 EMISSION CONTROL SYSTEMS EGR VALVE EGR VALVE (YELLOW STRIP) [C] (YELLOW STRIP) TO AIR CLEANER / EFE,., (PURPLE STRIP) D] (PURPLE STRIP) EFE ACTUATOR ACTUATOR TO AIR CLEANER SPARK CONTROL SWITCH PCV VALVE EGR VALVE ^ DIVERTER VALVE E (YELLOW STRIP) TO AIR ^ CLEANER //E F E w ACTUATOR DIVERTER VALVE THROTTLE RETURN CONTROL SPARK _ I rra CONTROL EJ / T SWITCH TO AIR CLEANER THROTTLE RETURN CONTROL TO AIR CLEANER THROTTLE RETURN CONTROL VALVE PCV VALVE THROTTLE RETURN CONTROL VALVE DIVERTER VALVE G 20 & 30 350/4 0 0 -V 8 CAL Fig. 4 -E m is s io n H ose R ou tin gs - G TR U C K SUP P - SER VIC E EMISSION CON TR O L SYSTEMS 8T-5 EARLY FUEL EVAPORATION SYSTEM - EFE GENERAL The early fuel evaporation (EFE) system improves cold engine warm-up by routing hot exhaust gases under the base of the carburetor which results in better atomization of fuel in a cold engine and helps reduce exhaust emissions during cold drive away. The EFE system consists of a vacuum controlled actuator which is linked to a stainless steel exhaust heat valve and a method of controlling vacuum source. When a cold engine is started, full vacuum pulls the spring-loaded diaphragm in the actuator and actuator rod closes the exhaust heat valve. This causes hot gases to be routed to the base of the carburetor. On six cylinder engine, the vacuum to the EFE actuator is controlled by an oil tem perature thermal vacuum switch (TCS) located in the right hand oil gallery (fig. 5). W hen oil tem perature reaches 150°F the switch opens and shuts-off vacuum to the EFE actuator. On small block V8 and 454 V8 the E FE actuator is controlled by a therm al vacuum switch (TVS) located on the engine inlet manifold (figs. 3 and 4). When coolant tem perature reaches 180°F, the switch shuts-off vacuum to the E FE actuator. W ithout vacuum, the vent on actuator opens, internal spring in actuator pushes the diaphragm back to its "at rest" position and actuator rod opens the exhaust heat valve. Spring loaded valve will remain open. SERVICE PROCEDURES INSPECTION • Visually inspect exhaust heat valve for damage or binding linkage. • Check that linkage is connected and vacuum hoses are properly routed and connected. • Move exhaust heat valve by hand. If binding or stuck, free with manifold heat valve lubricant, GM Part No. 1050422 or equivalent. If valve cannot be freed, replace valve. THERMAL V ACUU M SW ITCH (TVS) - V8 Coolant Temperature 2. Disconnect hoses at TVS ports. 3. Remove TVS. 4. Apply a soft setting sealant uniformly on replacement TVS male threads. No sealant should be applied to sensor end of TVS. 5. Install TVS, tighten to 120 pound inches and then hand torque clockwise as required to align TVS to accomodate hoses. 6. Connect hoses to TVS ports. 7. Add coolant as required. THERMAL V A C U U M SW ITCH (TVS) - L6 Oil Temperature The TVS is located on the engine coolant outlet housing or front of inlet manifold. The TVS is located on right hand oil gallery. Replacement Replacement 1. D rain coolant below level of engine coolant outlet housing. 1. Disconnect hoses at TVS ports. 2. Remove TVS switch. TRUC K SUP P - S E R V IC E 6T-6 EMISSION C O NTROL SYSTEMS 3. Install TVS switch. 4. Connect hoses to TVS ports. ACTUATOR AND ROD ASSEMBLY The actuator and rod assembly is located on a bracket attached to right exhaust manifold on V8 engines (figs. 6 and 7) and on left side attached to exhaust manifold on L6 engine (fig. 8). Replacement 1. Disconnect hose from actuator. 2. Remove 2 nuts attaching actuator-to-bracket. 3. Disconnect rod from valve and remove actuator and rod. 4. Install actuator and rod reversing steps 1 through 3. Tighten nuts to 25 pound inches. EXHAUST HEAT VALVE - V8 EXHAUST HEAT VALVE - L6 Replacement Replacement 1. Remove crossover exhaust pipe. Refer to Section 8 for removal and installation. 2. Disconnect rod from valve. 1. Remove 2 nuts attaching actuator bracket-to-valve and exhaust manifold. 2. Remove bracket and disconnect rod from valve. 3. Remove valve. 4. Install valve and connect rod. 3. Remove 2 additional nuts from valve and remove valve. 5. Install crossover exhaust pipe. 4. Install valve reversing steps 1 through 3. T R U C K SUPP - SER VIC E EMISSION CONTROL SYSTEMS 6T-7 DIAGNOSIS • If there is no vacuum TVS-to-vacuum source. CHECKING EFE SYSTEM 1. W ith engine cold, position transmission in neutral or park and apply parking brake. 2. Start engine and observe movement of actuator rod and exhaust heat valve. Valve should move to its closed position. 3. If valve does not close, disconnect hose at actuator and check for vacuum. disconnect hose at • If there is vacuum at hose, replace TVS. • If there is no vacuum, check for deteriorated hose and vacuum source to determine lack of vacuum. 4. W hen coolant reaches 180°F (small block V8 or 454 V8) or oil reaches 150°F (six cylinder), the exhaust heat valve should move to its open position. 5. If valve does not move, disconnect hose at actuator and check for vacuum. • If there is vacuum, replace actuator. • If there is vacuum, replace TVS. • If there is no vacuum, replace actuator. THROTTLE RETURN CONTROL SYSTEM - TRC GENERAL A throttle return control system (TRC) is used on a Light D uty Truck in California with V8 engine and heavy duty emissions. W hen vehicle is coasting against engine, the control valve will be open to allow vacuum to operate throttle lever actuator. The throttle lever actuator then pushes throttle lever slightly open, thus reducing hydro-carbon emission during coast down. W hen manifold vacuum drops below a pre-determined level the control valve closes, the throttle actuator retracts and throttle lever closes to idle position. SERVICE PROCEDURE CONTROL VALVE (Fig. 9) Check Diagnosis and Adjustment 1. Disconnect valve to carburetor hose at carburetor and connect to an external vacuum source equipped with a vacuum gauge. 2. Disconnect control valve to actuator hose at actuator and connect to a vacuum gauge. 3. Place finger firmly over end of bleed fitting (the foam air filter need not be removed). 4. Apply a minimum of 23 in. Hg. vacuum to control valve and seal off vacuum source. The gauge on actuator side should read the same as source gauge. It not, then control valve needs adjustment. If vacuum drops off on either gauge (finger still on bleed fitting), valve is leaking and must be replaced. TR U C K SUPP - S ER VIC E 6T-8 EMISSION CONTROL SYSTEMS FROM CARBURETOR V A C U U M COVER V A C U U M S W TIC H A D J U S T IN G SCREW V EN T FILTER M O U N T IN G BRACKET TO THROTTLE LEVER A C TU A TO R D IA P H R A G M THROTTLE T IG H T E N TO LEVER 150 IN . LBS. A C TU A TO R T IG H T E N TO 20 FT. LBS. C O N TR O L VALVE C O N TR O L VALVE F ig . 9 - T h r o t t le R e tu rn C o n tro l V a lv e 5. With a minimum 23 in. Hg. vacuum level in control valve, remove finger from bleed fitting. The vacuum reading on actuator side will drop to zero and reading on source gauge will drop to a value which is the valve set poin t. The valve set point for a 350/400 V8 is 21.5 in. Hg. and for a 454 V8 is 21.0 in. Hg. If this value is not within .50 in. Hg. of the specified valve set point, then the valve must be adjusted. 6. To adjust the valve set point: a. Gently pry off the conical plastic cover. b. Turn the adjusting screw in (clockwise) to raise the set point or out (counterclockwise) to lower the set point value. c. Recheck the valve set point per steps No. 3 and 5. d. Repeat steps 6b and c as necessary to obtain the specified value within .50 in. Hg. 8. Reinstall plastic cover. 9. If the valve cannot be adjusted it must be replaced. Replacement Disconnect vacuum hoses at control valve. Remove nut, washer and control valve. Reverse procedure to install and check operation of control valve. TRUC K S U P P • SER VIC E EMISSION CONTROL SYSTEMS 6T-9 THROTTLE LEVER ACTUATOR (Fig. 10) Replacement Check and Diagnosis Disconnect vacuum hose at actuator. Remove two screws and actuator. Reverse procedure to install and refer to throttle lever actuator for adjustment. 1. Disconnect valve to actuator hose at valve and connect to an external vacuum source equipped with a vacuum gauge. 2. Apply 20 in. Hg. vacuum to actuator and seal off the vacuum source. If vacuum gauge reading drops, then actuator is leaking and must be replaced. 3. To check actuator for proper operation: a. Check throttle lever, shaft, and linkage to be sure that they operate freely w ithout binding or sticking. b. Start engine and run until warmed up and idle is stable with transmission in neutral or park. Note idle rpm. c. Apply 20 in. Hg. vacuum to the actuator. Manually open the throttle slightly and allow to close against the extended actuator plunger. Note engine rpm. d. Release and reapply 20 in. Hg. vacuum to actuator and note rpm to which engine speed increases (do not assist actuator). e. If rpm obtained in step 3d is not within 150 rpm of that obtained in step 3c, then the actuator plunger may be binding due to dirt, corrosion, varnish, etc. or actuator diaphragm may be too weak. If binding is not indicated or cannot be corrected then the actuator must be replaced. f. Release the vacuum from the actuator and the engine speed should return to within 50 rpm of the idle speed noted in step 3b. If it does not, the plunger may be binding due to dirt, corrosion, varnish, etc. It the problem cannot be corrected, the actuator must be replaced. 4. If the engine rpm noted in 3c is not within the specified TRC speed range, adjust throttle lever actuator. Adjustment (Fig. 11) 1. Disconnect valve to actuator hose at valve and connect to an external vacuum source equipped with a vacuum gauge. 2. Check throttle lever, shaft, and linkage to be sure that they operate freely without binding or sticking. 3. Start engine and run until warmed up and idle is stable. Place transmission in neutral or park. 4. Apply 20 in. Hg. vacuum to actuator. M anually open throttle slightly and allow to close against the extended actuator plunger. Note the engine rpm. 5. If rpm noted above is not within specified TRC speed range, then turn plunger screw on actuator plunger in the appropriate direction and repeat step No. 4 until specified T R C speed range is obtained. The TRC speed range for a 350/400 V8 is 1500 rpm and for a 454 V8 is 1400 rpm. Fig. 1 0 -T h r o ttle Lever A c tu a to r TR U C K SUP P • SER VIC E S E C T IO N 6 Y ENGINE ELECTRICAL NOTE: Except for the following changes, all information listed in Section 6Y of the 1974 Truck Service M anual is applicable to 1976 light duty trucks. Refer to 1974 Truck Service M anual for any service procedure not contained herein. Illustrations showing complete engine wiring for each truck line are shown in figures 1 through 11. TR U C K S U P P - S ER VIC E 6Y-2 ENGINE ELEC TR IC A L \ S TA R TIN G M O T O R FW D^ V IE W B N O TE PRESS B O O T OVER TER M IN A L W IT H SMALL E N D D O W N . LEFT SIDE Fig. 2 --C -1 0 (0 3 ) w / F 4 4 , C -1 0 (0 6 ) & (1 6 ) and K -1 0 L-6 (L D 4 ) E ng ine W irin g O IL PRESS. TEMPERATURE S W IT C H V IE W A LEFT SIDE N O T E INSTALL G E N E R A T O R LEAD P O IN T IN G IN B O A R D S O TH A T C O N D U IT W ILL N O T INTERFERE W IT H TH E R M A C H EAT TU B E . V ]E W B R IG H T SIDE Fig. 3 - C - K -1 0 th ru 3 0 T ru c k V -8 ( L F 4 /L G 9 /L S 9 ) E n g in e W irin g TR U C K S UPP - SER VIC E ENG INE E LE C TR IC A L 6Y-3 C A R B U R E TO R W /S W IP E R M O T O R D IS TR IB U TO R A S M BAT. CABLE GENERATOR T O FUEL METER N O T E PRESS B O O T O VER TE R M IN A L W IT H SMALL E N D UP LP H A R N REAR LP H A R N O IL PRESS. S W V IE W B HARN V IE W A \ TEM P. S W TEM P. S W . S T A R T IN G M O T O R BAT. CABLE (1 2 A ) O IL PRESS. S W . FW D =* R IG H T SIDE O IL PRESS. EAD V IE W A WyJ V IE W B V IE W C V IE W C p u r p le ^ N O T E T H IS C O N N E C T IO N M U S T BE P O S IT IO N E D AS S H O W N . V )E W D Fig. 4 --C -1 0 th ru 3 0 T ru c k V -8 (L F8) E ng ine W irin g ft — IDLE STOP SOL | O IL PRESSURE / EXC. 153 "1 B U LK H E A D C O N N P A R K IN G BRAKE CABLE SPE E D O CABLE ■N O T E R O UTE H A R N . R E AR W A R D OF P U M P BRACE. BAT. CABLE N O T E PRESS B O O T y V IE W A TEM P. G A G E O V E R T E R M IN A L W IT H SMALL E N D D O W N . \ X / S T A R T IN G M O T O R V IE W A F W D . LAMP H A R N E N G . HARN D A SH PANELCOOLANT \ ^ HEATER B LO W ER R ECO VERY TANK O IL SEN D E R A S M . V IE W C V IE W C & 152 R IG H T SIDE V IE W B Fig. 5 - G - 1 0 th ru 3 0 T ru c k L-6 (L D 4 ) E n g in e W irin g TR U C K S U P P - S ER VIC E 6Y-4 ENGINE E LE C TR IC A L CARB. SOL TO TEM P S W IT C H W ^ COOLANT B U LK H E A D C O N N . ^ - TEMP. S W IT C H \>vi i iU , ^ RECOVERY TANK P A R K IN G BRAKE C A B L E T ^ ' ''W ' SPE E D O CABLE BAT. CABLES TEMP. S W IT C H X * Wf . ■ EN. . / S T A R T IN G M O T O R A S M . V V |E W B O IL PRESSURE S W IT C H / I V IE W A M rf/Z N O T E PRESS B O O T OVER $ {[ff'7 TE R M IN A L W IT H SMALL E N D D O W N . j y ° li s e n d e r a s m .v O ENG. HARN. HEATER B LO W ER FW D . LAAAP HARN D A S H PANEL V IE W A V IE W C R IG H T SIDE V IE W C V IE W B Fig. 6 --G -1 0 th ru 3 0 T ru c k L-6 (L 2 5 ) E ng ine W irin g HARN O IL PRESS. S W B U LK H E A D C O N N SPE E D O CABLE BAT. CABLE STARTER M O T O R HARN P A R K IN G BRAKE CABLE E N G . H A R N (1 2 H ) F W D . LAMP H A R N V IE W A V IE W A TEM P. S W IT C H / N O T E T H IS C O N N E C T IO N V IE W B M U S T BE P O S IT IO N E D AS S H O W N V IE W B N O T E PRESS. B O O T O VER T E R M IN A L W IT H SMALL E N D D O W N . \ V IE W C C O O L A N T R ECO VERY T A N K M O D U L A T O R PIPE (7 A ) E N G . HARN HEATER BLOW ER V IE W C R IG H T SIDE Fig. 7 --G -1 0 th ru 3 0 T ru c k V -8 ( L F 4 /L G 9 /L S 9 ) E ng ine W irin g T R U C K S U P P ■ S ER VIC E ENG INE E LE C TR IC A L 6Y-5 E N G IN E H A R N E S S CA R B . SOL D A S H PA NEL PCV H O S E m / / E N G .y ^ f O J T E M P .S w l V IE W A HARN :HARN B A C K IN G LP S W W A TE R TEM P. S W V IE W A SENSOR ASM GENERATOR B A C K IN G LAMP V IE W C BATTERY CABLE PURPLE N E U TR A L SAFETY B A C K IN G LAMP S W V IE W B N O T E PRESS B O O T O V E R T E R M IN A L W IT H SMALL E N D D O W N . R IG H T SIDE V IE W D Fig. 8 --P -1 0 th ru 3 0 T ru c k L-6 (L 2 5 ) E ng ine W irin g BATTERY CABLE HARN SENSOR ASM TEMP. SW ITCH B A C K IN G LAMP SW ITC H M 2 0 V IE W A STARTING MOTOR S O LEN O ID FUEL METER WIRE FUEL PIPE " V IE W * FW D NOTE PRESS BOOT OVER TERMINAL W ITH SMALL END D O W N FUEL PIPE —Ta TRANS. ASM HARN E N G . W R G . HARN V IE W C V IE W A V IE W B NEUTRAL SAFETY \ STARTING MTR SO LE N O ID BAT. CABLE B A C K IN G LAMP SW ITCH & B A C K IN G LAMP SW ITCH LEFT SIDE RIGHT SIDE Fig. 9 --P -1 0 th ru 3 0 T ru c k (E xc ep t 3 2 ) T ru c k V -8 (L S 9 ) E n g in e W irin g TR U C K S U P P - S E R VIC E 6Y-6 ENGINE ELEC TR IC A L GENERATOR NEUTRAL SAFETY & B A C K IN G LAMP CONNECTOR SENSOR ASM TO J U N C T IO N BLOCK TO DASH PANEL NOTE PRESS BOOT OVER TERMINAL W ITH SMALL TEMP SW ITCH LEAD V IE W B END D O W N . V IE W A V IE W A BATTERY CABLE TRANS. S O LEN O ID NEUTRAL SAFETY & BATTERY CABLE B A C K IN G LAMP WIRE ASM. (7A) TO FUEL METER VIEW B V IE W C V ltW C PURPLE RIGHT SIDE Fig. 1 0 --P -3 0 (3 2 ) T ru c k V -8 (L S 9 ) E ng ine W irin g SO LE N O ID EXC. NB2 GENERATOR BRACE TO DASH PANEL V IE W C TO DASH PANEL V IE W A ^ to |DLE STOP SOL BATTERY CABLE SW ITCH ASM WM. V / V IE W A NEUTRAL SAFETY & B A C K IN G LAMP SW. STARTING M OTOR SO LE N O ID TRANS. SO LE N O ID PURPLE VIEW B BATTERY CABLE SO LE N O ID EXC. NB2 FUEL PIPE ASM .SENSOR ASM STARTING M OTOR SO LE N O ID TO FUEL METER VIEW B RIGHT SIDE V IE W A Fig. 1 1--P -30 T ru c k V -8 (L F8) E ng ine W irin g T R U C K SUP P - SER VIC E ENGINE E LE C TR IC A L 6Y-7 CHARGE IN D IC A TO R VEN T (2) TERMINAL Fig. 2 b --B a tte ry C h a rg e In d ic a to r Fig. 1b--F reedo m B a tte ry FREEDOM BATTERY The Freedom (M aintenance Free) Battery (fig. lb) has more electrolyte in the cells than regular vent cap type batteries. W ith the reduced water usage, water never needs to be added. Actually, water can not be added. There are no vent plugs in the cover. The battery is completely sealed except for 2 small vent holes on the side. These vent holes allow what small am ount of gases that are produced in the battery to escape. The special chemical composition inside the battery reduces the production of gas to an extremely small am ount at norm al charging voltages. C h a r g e I n d ic a to r - D a rk (G re e n D o t N o t V isib le) (Fig. 2 b) If the charge indicator is dark and the green dot is not visible, charge battery until dot appears, but not more than 60 ampere-hours (for example, 15 amperes for four hours). NOTE: Some chargers are constant current chargers while others are constant voltage chargers. If a constant voltage charger is used for charging the battery and the green dot fails to appear after prolonged charging, it may be necessary to tip the battery slightly from side to side a few times for the green dot to appear. C h a r g e I n d ic a to r - L ig h t (Fig. 2 b ) A charge indicator located in the cover indicates state of charge. This feature will be fully explained in the following paragraph. Testing Freedom Battery Visual Inspection If the charge indicator is light replace battery. DO NOT attem pt to charge or "jump" when charge indicator is light. NOTE: A battery that failed prematurely, and exhibited a light charge indicator condition, may indicate a need for checking the charging system of the vehicle. Remove Surface Charge Check for obvious damage, such as a cracked or broken case Connect a 300 ampere load across battery terminals for 15 seconds to remove surface charge from battery. or cover that could permit loss of electrolyte. If obvious Load Test physical damage is noted, replace battery. Also, determine cause of damage and correct as required. C h a r g e I n d ic a to r - D a r k (G re e n D o t V isib le) (Fig. 2b) If the charge indicator is dark and has a green dot in the center, the battery is sufficiently charged for testing. 1. Connect voltmeter and an ampere load across battery terminals as indicated below: BATTERY TYPE AMPS FOR LOAD TEST R85-5 Y 854 R87-5 170 130 210 T RUC K SUP P - S ER VIC E 6Y-8 ENGINE ELEC TR IC A L 2. Read voltage after 15 seconds with load connected and then disconnect load. 3. If minimum voltage is 9.6* volts or more, battery is good. 4. If minimum voltage is less than 9.6* volts, replace battery. * This voltage is to be used for battery ambient temperatures of70°F and above. For temperatures below 70°F, use the following: MINIM U M VO LTA G E 60° F 9.5 50° F 9.4 40° F 9.3 30° F 9.1 20° F 8.9 10°F 8.7 0° F 8.5 10-SI SERIES GENERATOR The 1976 10-SI generator is mostly carryover from 1974. The only difference being that a 40-ohm resistor has been added to the warning indicator circuit (figs. lc and 2c). The purpose of this resistor is to provide a definite warning indicator light in the case of an open field circuit in the generator. Refer to Section 6Y of the 1974 Truck Service M anual for all service procedures. BRUSH HOLDER 4 0 -O H M RESISTOR EGULATOR INSULATED HEAT SINK IN S U L A T IN G W ASHER GROUNDED HEAT SINK Fig. 2 C -R e s is to r L o catio n Fig. 1 C -ln te g r a l C h a rg in g S ystem C irc u itry f T R U C K SUP P - SER VIC E ENG INE E LE C TR IC A L 6Y-9 STARTER SYSTEM The 1976 starter is mostly carryover from 1974. The only difference being that the "R " terminal of the starter solenoid has been removed. This term inal was removed because with the High Energy Ignition System there is no longer any requirem ent for the electrical lead from the starter solenoid to the ignition coil. Refer to Section 6Y of the 1974 Truck Service M anual for all service procedures. HIGH ENERGY IGNITION SYSTEM INDEX G eneral Description............................................... t... Theory of O p eration................................................... Service O perations....................................................... Routine M aintenance............................................... Electronic M odule..................................................... Spark Plug W ires...................................................... Timing Light C onnections...................................... Tachometer Connections.......................................... O ther Test E quipm ent............................................. Centrifugal/V acuum A dvance............................... D istributor................................................................... R em oval..................................................................... 6Y-10 6Y-11 6Y-12 6Y-12 6Y-12 6Y-12 6Y-12 6Y-12 6Y-12 6Y-12 6Y-12 6Y-12 Installation................................................................ 6Y -13 Disassembly............................................................... 6Y-13 Assem bly................................................................... 6Y-13 Ignition Coil (8 C ylinder)....................................... 6Y-15 R em oval.................................................................... 6Y-15 Installation................................................................ 6Y-15 Ignition Coil (6 C ylinder)....................................... 6Y-15 R em oval..................................................................... 6Y -15 Installation................................................................ 6Y-15 Diagnosis..................................................................... 6Y-17 T R U C K SUP P - S E R VIC E 6Y-10 ENG INE E LEC TR IC A L GENERAL DESCRIPTION There are two types of High Energy Ignition (H EI) distributors. The 8 cylinder distributor (fig. li) combines all ignition components in one unit. The ignition coil is in the distributor cap and connects directly to the rotor. The 6 cylinder distributor (fig. 2i) has an external mounted coil. Both operate basically in the same m anner as a conventional ignition system except the module and pick-up coil of the H E I system replace the contact points of the conventional system. IGNITION CO IL CONN ECT TACHOMETER FROM THIS TERM INAL TO GROUND. BAT. TERMINAL (CONNECTED TO IGNITION SWITCH) H IGH ENERGY IGNITION DISTRIBUTE GROUND TERMINAL (SOME TACHOMETERS MUST CO NNECT FROM THIS TERMINAL TO ENERGIZER POSITIVE (+ ). SOME TACHOMETERS M AY NOT W O RK AT ALL. CONSULT TACHOMETER MANUFACTURER.) CO N N ECTO R BAT. TERMINAL (CONNECTED TO IGNITION SWITCH) LATCH (4) LEAD \ TO SPARK PLUG VACUUM UNIT H O U SIN G LATCH (4) li CONNECT TACHOMETER FROM THIS TERMINAL TO GROUND. TACH TERMINAL (SOME TACHOMETERS MUST CONNECT FROM THIS TERMINAL TO ENERGIZER POSITIVE ( + ) CONSULT TACHOMETER MANUFACTURER.) Fig . 1 i—8 C y lin d e r HEI D is tr ib u to r The High Energy Igntion is a pulse triggered, transistor controlled, inductive discharge ignition system. The magnetic pick-up assembly located inside the distributor contains a perm anent magnet, a pole piece with internal teeth, and a pick-up coil. W hen the teeth of the tim er core rotating inside the pole piece line up with teeth of the pole piece, an induced voltage in the pick-up coil signals the all electronic module to open the coil prim ary circuit. The primary current decreases and a high voltage is induced in the ignition coil secondary winding which is directed through the rotor and high voltage leads to fire the spark plugs. The capacitor in the distributor is for radio noise suppression. The module automatically controls the dwell period, stretching it with increasing engine speed. The H E I system also features a longer spark duration, made possible by the higher am ount of energy stored in the coil primary. This is desirable for firing lean and E G R diluted mixtures. F ig . 2 i—6 C y lin d e r HEI D is tr ib u to r Ignition Coil In the 8 cylinder H EI system, the igntion coil is built into the distributor cap. In the 6 cylinder H EI system, the ignition coil is mounted externally. The coil is somewhat smaller physically than a conventional coil, but has more primary and secondary windings. It is built more like a true transformer with the windings surrounded by the laminated iron core. A conventional coil has the iron core inside the windings. A lthough the H EI coil operates in basically the same way as a conventional coil, it is more effective in generating higher secondary voltage when the primary circuit is broken. Electronic M odule The electronic module is a solid state unit containing five complete circuits which control spark triggering, switching, current limiting, dwell control and distributor pick-up. Dwell angle is controlled by a transistor circuit within the module and is varied in direct relation to engine speed. Pick-Up Assem bly The pick-up assembly consists of the following: 1. A rotating tim er core with external teeth which is turned by the distributor shaft. TRUC K S U P P - S E R VIC E ENGINE E LE C TR IC A L 2. A stationary pole piece with internal teeth. 3. A pick-up coil and magnet which are located between the pole piece and a bottom plate. C entrifugal and Vacuum A dvance The centrifugal and vacuum advance mechanisms are 6Y-11 basically the same types of units that provide spark advance in the breaker-type system. Centrifugal advance is achieved through the rotation of the tim er core in relation to the distributor shaft. Vacuum advance is achieved by attaching the pick-up coil and pole piece to the vacuum advance unit actuating arm. THEORY OF OPERATION The pick-up coil is connected to transistors in the electronic module. The electronic module is connected to the primary windings in the coil. As the distributor shaft turns the timer core teeth out of alignment with the teeth of the pole piece a voltage is created in the magnetic field of the pick-up coil. The pick-up coil sends this voltage signal to the electronic module, which determines from RPM when to start current building in the prim ary windings of the ignition coil. Each time the tim er core teeth align with the pole piece teeth the pick-up coil magnetic field is changed creating a different voltage. The pick-up coil sends this different voltage signal the electronic module which electronically shuts off the ignition coil prim ary circuit. This in turn collapses the coil magnetic field, induces high secondary voltage and fires one spark plug. The electronic m odule delivers full battery voltage to the ignition coil which is limited to five to six amperes. There is no primary resistance wire in the H EI system. The electronic module triggers the closing and opening of the primary circuit instantaneously with no energy lost due to breaker point arcing or capacitor charging time lag. The capacitor in the H E I unit functions only as a radio noise suppressor. This instantaneous and efficient circuit triggering enables the H EI system to deliver up to approximately 35,000 volts through the secondary wiring to the spark plugs. F ig . 3 i- H ig h E n e rg y Ig n itio n B a s ic W ir in g Because of the higher voltage, the H EI system has larger diameter (8 millimeter) spark plug wires with silicone insulation. The silicone wire is orange in color, more heat resistant than standard black wire and less vulnerable to deterioration. Silicone insulation is soft, however, and must not be mishandled. T R U C K S U P P - S E R VIC E 6Y-12 ENGINE ELEC TR IC A L SERVICE OPERATIONS CYL N O . 6 Routine M a in ten an ce CYL N O . 5 CYL N O . 4 The H E I system is designed to be free from routine maintenance. If component part replacement should become necessary, however, several items specific to the H E I system should be noted. CYL N O . 3 CYL N O . 2 CYL N O . I Electronic M odule The electronic module is serviced by complete replacement only. When replacing the module a liberal coating of special silicone grease M UST be applied to the metal mounting surface on which the module will be installed. If this grease is not applied the module will not cool properly which can cause the module to malfunction. A tube of this special silicone grease is supplied with each replacement module. Spark Plug W ire s (Figs. 4 if 5i) The 8 millimeter silicone insulation spark plug wire boots seal more tightly to the spark plugs. Twist the boot about a half turn in either direction to break the seal before pulling on the boot to remove the wire. F ig . 5 i—6 C y lin d e r HEI Ig n itio n W ir in g W ARNING: Do N ot remove spark plug wires with the engine running. The higher secondary voltage is capable of jum ping an arc of greater distance and could cause an electric shock. T achom eter Connections In the distributor cap connector is a "tach" terminal. Connect the tachom eter to this terminal and to ground. Some tachometers must connect from the "tach" terminal to the battery positive ( + ) terminal. Follow tachometer m anufacturer’s instructions. CAUTION: Grounding "tach" terminal could damage the HEI electronic module. CYL # 8 CYL O th er T est Equipm ent CYL CYL # 2 CYL # 5 CYL # 7 CYL #1 Oscilliscopes require special adaptors. D istributor machines require a special amplifier. The equipment manufacturers have instructions and details necessary to modify test equipment for H E I diagnosis. Vacuum and C en trifu g al Advance Specifications CYL CYL # 6 Vacuum and centrifugal advance specifications are listed in the Specifications Section of this manual. CYL # 4 CYL # 2 D istributor CYL # 5 F ig . 4 i—8 C y lin d e r HEI Ig n itio n W ir in g Removal 1. Disconnect wiring harness connectors at side of distributor cap. 2. Remove distributor cap and position out of way. 3. Disconnect vacuum advance mechanism. Tim ing Light Connections Timing light connections should be made in parallel using an adapter at the distributor num ber one terminal. advance hose from vacuum 4. Scribe a m ark on the engine in line with rotor. Note approximate position of distributor housing in relation to engine. TR U C K S UPP - SER VIC E ENG INE E LE C TR IC A L 5. Remove distributor hold-down nut and clamp. 6Y-13 ADVANCE W EIGHT (2) 6. Lift distributor from engine. Installation 1. Install distributor using same procedure as for standard distributor. 2. Install distributor hold-down clamp and snugly install nut. 3. Move distributor housing to approximate position relative to engine noted during removal. 4. Position distributor cap to housing with tab in base of cap aligned with notch in housing and secure with four latches. 5. Connect wiring harness connector to terminals on side of distributor cap. C onnector will fit only one way. 6. Adjust ignition timing as described in Specification Section of this manual. F ig . 6 i- D is t r ib u t o r C e n tr ifu g a l A d v a n c e D istribu tor Disassembly (Figs. 6i - 8i) 1. Remove distributor as described above. 2. Remove rotor from distributor shaft by removing two screws. 3. Remove two advance springs, weight retainer, and advance weights. 4. Remove two screws holding module to housing and move module to a position where connector may be removed from ’B’ and ’C ’ terminals. 5. Remove wires from "W " and "G " terminals of module. 6. Remove roll pin from drive gear. C A U T I O N : Distributor gear should be supported in such a way that no damage will occur to distributor shaft while removing pin. 7. Remove gear, shim and tanged washer from distributor shaft. Remove any burrs that may have been caused by removal of pin. 8. Remove distributor shaft from housing. 9. Remove washer from upper end of distributor housing. 10. Remove lock ring at top of housing and remove pole piece and plate assembly and felt washer. N OTE: No attem pt should be made to service the shaft bushings in the housing. 11. Remove vacuum advance mechanism by removing two screws. 12. Disconnect capacitor lead and remove capacitor by removing one screw. 13. Remove wiring harness from distributor housing. Assembly (Figs. 6i - 9i) F ig . 7 i—R olI P in R e m o v a l 3. Lubricate felt wick with a few drops of m otor oil and install replacement pole piece and plate assembly over upper bushing and vacuum advance unit. Make sure the retainer (bow) that holds the white and green electrical leads together is color coded yellow. 4. Install lock ring pole piece and plate assembly. 5. Place distributor shaft distributor housing. (with rotor attached) in 1. Position vacuum advance unit to housing and secure with two screws. 6. On 8 cylinder distributors, install tanged washer, shim and drive gear on distributor shaft. 2. Position felt washer over lubricant reservoir at top of housing. 7. On 6 cylinder distributors, install drive gear on distributor shaft. TRUC K S UPP • S E R V IC E 6Y-14 ENGINE ELEC TR IC A L is not applied, the module will not cool properly, which can cause the module to malfunction. A tube of this special silicone grease is supplied with each replacement module. 1. Raise hood and remove air cleaner. 2. Release distributor cap out-of-the-way place. and place aside in an 3. Remove two screws and remove rotor from distributor shaft. 4. Remove two screws holding module to housing and move module to a position where electrical connector may be removed from B and C terminals of module. 5. Use needle nose pliers or similar tool to remove pole piece and plate assembly electrical leads from W (White) and G (Green) terminals of module. Do not remove leads by pulling on the wires as damage to the leads may occur. F ig . 8 i- T o p V ie w o f D is tr ib u to r H o u s in g 8. Align holes of drive gear with hole of distributor shaft so that locating m ark on drive gear is in line with tip of rotor. Support distributor shaft on a wooden block or other suitable object and install roll pin. Make sure distributor is supported in such a way that no damage will occur to distributor shaft while installing roll pin. 6. Install replacement module in reverse order of removal. During installation, make sure a liberal amount of special silicone grease is applied to the metal mounting surface of module to insure proper cooling. 7. Check operation of new module by starting and running vehicle. Pole Piece and Plate Assembly Replacement (Figs. 7i - 9i) 13. Position wiring harness with grommet in housing notch. The pole piece and plate assembly is serviced by complete replacement only. The three screws securing stationary pole piece and perm anent magnet should not be disturbed except under extreme conditions since the pole piece is adjusted by the factory to critical dimensions. During replacement, make sure the replacement pole piece and plate assembly is the correct specified part. One quick m ethod of assuring a correct part is to observe the retainer (bow) that holds the white and green electrical leads together is color coded yellow. The correct pole piece and plate assembly for all 6 and 8 cylinder engines are color coded yellow. 14. Connect pink wire to capacitor stud, and black wire to capacitor mounting screw. Tighten screw. 1. Remove distributor as described previously in this section. 15. Connect white wire from pick-up coil to terminal "W" module. 2. Support distributor gear on a block of wood or other suitable object (fig. 7i) and drive roll pin from drive gear. Make sure distributor is supported in such a way that no damage will occur to distributor shaft while removing roll pin. 9. Check to make sure shaft is not binding by spinning shaft a few times by hand. 10. Position capacitor to housing and loosely install one mounting screw. 11. Install connector to "B" and "C" terminals on module with tab on top. 12. Apply special silicone lubricant liberally to bottom of module and secure with two screws. 16. Connect green wire from pick-up coil to terminal "G" of module. 17. Install centrifugal advance weights, weight retainer (dimple facing down), and springs. 18. Install rotor and secure with two screws. CAUTION: Notch on side o f rotor must engage tab on cam weight base. 19. Install distributor as described above. Electronic Module Replacement (Fig. 8i) The electronic module is serviced by complete replacement only. When replacing the module a liberal coating of special silicone grease M UST be applied to the metal mounting surface on which the module will be installed. If this grease 3. On 8 cylinder distributors, remove drive gear, shim and tanged washer from distributor shaft. 4. On 6 cylinder distributors, remove drive gear from distributor shaft. 5. Remove any burrs that may have been caused by removal of roll pin and remove shaft (with rotor attached) from distributor housing. 6. Use needle nose pliers or similar tool to remove pole piece and plate assembly electrical leads from W (White) and G (Green) terminals of module. Do not remove leads by pulling on the wires as damage to the leads may occur. TRUC K SUP P - SER VIC E ENGINE E LE C TR IC A L 7. Remove lock ring from top of pole piece and plate assembly (fig. 8i) and remove pole piece and plate assembly from distributor housing. 8. Lubricate felt wick with a few drops of m otor oil and install replacement pole piece and plate assembly over upper bushing and vacuum advance unit. Make sure the retainer (bow) that holds the white and green electrical leads together is color coded yellow. 9. Install lock ring (fig. 8i) and then connect green electrical lead of pole piece and plate assembly to G terminal of module. Then connect white lead of pole piece and plate assembly to W term inal of module. 10. Place distributor shaft distributor housing. (with rotor attached) in 11. On 8 cylinder distributors, install tanged washer, shim and drive gear on distributor shaft. 12. On 6 cylinder distributors, install drive gear on distributor shaft. 13. Align holes of drive gear with hole of distributor shaft so that locating m ark on drive gear is in line with tip of rotor. Support distributor shaft on a wooden block or other suitable object and install roll pin. Make sure distributor is supported in such a way that no damage will occur to distributor shaft while installing roll pin. 6Y-15 14. Check to make sure shaft is not binding by spinning shaft a few times by hand. 15. Install distributor as described previously in this section. Ignition Coil-8 Cylinder Removal (Fig. 10i) 1. Disconnect battery wire and harness connector from distributor cap. 2. Remove three screws securing coil cover to distributor cap. 3. Remove four screws securing ignition coil to distributor cap. 4. Remove ground wire from coil. 5. Push coil leads from under side of connectors and remove coil from distributor cap. Installation (Fig. 10i) 1. Position coil into distributor cap with terminals over connector at side of cap. 2. Push coil lead wires into connector on side of cap as follows: black (ground) in center; brown next to vacuum advance unit; pink opposite vacuum advance unit. 3. Secure ignition coil with four screws. Place ground wire under coil mounting screw. 4. Install coil cover onto distributor cap and secure with three screws. Ignition Coil-6 Cylinder Removal (Fig. 5i) 1. Disconnect ignition switch to coil lead at coil. 2. Disconnect coil to distributor leads at coil. 3. Remove 4 screws securing coil to side of engine and remove coil. Installation (Fig. 5i) 1. Install coil to side of engine with 4 screws. 2. F ig . 9 i—R o ll P in In s ta lla tio n Connect coil to distributor leads at coil. 3. Connect ignition switch to coil lead at coil. TRUC K SUP P - S E R VIC E 6Y-16 ENGINE ELEC TR IC A L COVER SEAL SPRING ROTOR VACUUM UNIT H O U S IN G WASHER GEAR CONNECTOR F ig . 1 0 i- E x p lo d e d V ie w o f 8 C y lin d e r HEI D is tr ib u to r TR U C K SUP P - SER VIC E ENG INE E LE C TR IC A L 6Y-17 DIAGNOSIS HIGH ENERGY IGNITION SYSTEM L-6 engines PROBLEM: engine CRANKS but WILL NOT START C O IL PIC K -U P C O IL MODULE SEQUENCE STEP RESULT AU TO TRANS. LEVER IN PARK TEST LIG H T ON M A N U A L TRANS. CONNECT TEST LIG H T TO BAT. LEAD TERM. LEVER IN NEUTRAL TEST LIGH T OFF IG N ITIO N SW. -------- Q STARTS 0 — REPAIR OR REPLACE AS NECESSARY -® " | TEST LIG H T | ON NO START REMOVE A SPARK PLUG WIRE INSERT EXTENSION AND PERFORM SPARK TEST ® — NO SPARK USING IN S U LATED PLIERS HOLD SPARK PLUG WIRE 1 /4 ' A W AY FROM ENG. BLOCK W HILE C R AN KIN G ENGINE ■ _________________ PROBLEM IS NOT IG N ITIO N SYSTEM CHECK SPARK EXTENSION - • FUEL SYSTEM •P LU G S •F L O O D E D -----------( s t o p ) STARTS O 3 I V IS U A L L Y INSPECT REPAIR AS l_ FOR MOISTURE. DUST, NECESSARY CRACKS, BURNS, ETC. NO START T R U C K S U P P - SER VIC E 6Y-18 ENGINE ELEC TR IC A L HIGH ENERGY IGNITION SYSTEM L-6 engines STEP SEQUENCE CONNECT OO -V _ _ . OHMMETER READS ABOVE 1 OHM (X 1 SCALE) RESULT STARTS REPLACE COIL NO START DISCONNECT CONNECTOR READS 0 TO 1 OHM (X 1 SCALE) READS 6.000 TO 30,000 OHMS CONNECT OHMMETER STARTS READS MORE THAN 30,000 REPLACE OHMS OR LESS THAN C 0| L 6,000 OHMS CONNECT OHMMETER LESS THAN INFINITY NO START STARTS - ---REPLACE C0IL NO START READS INFINITE (X 1000 SCALE) REMOVE GREEN & WHITE LEADS FROM MODULE STARTS — o-----' U @ X -------------“ CONNECT OHMMETER FROM GRQUND TO EITHER LEAD y f LESS THAN INFINITY REPLACE COIL (PICK UP) (X 1000 SCALE) / ------------- \ ° ° V - ------- > / _ READS INFINITE (X 1000 SCALE) CONNECT OHMMETER ACROSS 2 LEADS READS 500 TO 1500 OHMS NO START REPEAT STEPS 8 AND 9 WHILE MOVING VAC. ADVANCE WITH SCREW DRIVER. IF READING IS STILL OK STARTS DOES NOT READ 500 TO 1500 OHMS REPLACE COIL (PICK-UP) NO START REPEAT STEPS 5 THRU 9 CHECK MODULE WITH TESTER REMOVE AND REPLACE MODULE TRUC K SUP P - SER VICE ENGINE E LE C TR IC A L 6Y-19 HIGH ENERGY IGNITION SYSTEM L-6 engines PROBLEM: engine RUNS ROUGHor CUTS OUT SEQUENCE STEP RESULT ® - ------------- , „ --------- -------------------- (sto p ) X -X ® C H EC K SPARK PLUG S & PLUG W IR ES _ - 0 — — i |r u n s s m o o th &r~--------1 R E P A IR OR RE PLA CE RUNS ROUGH CD ^ J ^ ) REM0VE CAP ASSY. - -------------- @ R U N S SM O O TH V IS U A L L Y INSPEC T FO R M O IS T U R E , DU ST, R E P A IR AS NECESSARY C R AC KS, BURNS, ETC. — RU NS R O U G H ------------------------------------------------------------------------------------------------------ ----— r EAD F 4n<: nnn R S k 6,0 00 m TO I __ 3 0 ,000 OHM S r - @ C ^>— READ S M O R E T H A N 30,0 0 0 OHMS OR LESS T H A N REPLA CE C 0 (L - — R U N S SM O O TH -0 , © SN —— 5 ('' ') 6,0 0 0 O HM S R U N S R O UG H R E M O V E G R EE N & W H ITE I l e a d s FR O M M O D U L E CONNECT O H M M E TER FROM oo G R O U N D TO E IT H E R R E A D S IN F IN IT E LEAD (X 1000 SC A LE ) CO NNECT O H M M E TER ACROSS 2 LE ADS READ S 5 0 0 TO 1500 O HM S R E P E A T STEPS 4 A N D 5 W H IL E M O V IN G VA C. A D V A N C E W IT H SCREW ­ D R IV E R . IF R E A D IN G IS S T IL L OK 'R U N S SM O O TH DO ES N O T R E A D 500 T O 1500 O HM S REPLA CE C O IL (PICK-U P) RU N S R O UG H R E P E A T STEPS (OK) 1 THRU 5 IF O K © CHECK M O D ULE W IT H TESTER ----------------------- ( s t o p ) IF NO T OK R E M O VE A N D REPLACE M O D ULE TR U C K S U P P - S ER VIC E 6Y-20 ENGINE ELEC TR IC A L HIGH ENERGY IGNITION SYSTEM V8 engine CO VER PROBLEM: engine CRANKS but WILL NOT START 3-W IRE CONNECTO R C O IL PICK-UP C O IL STEP SEQUENCE RESULT AU TO TRANS. LEVER IN PARK TEST LIG H T ON M A N U A L TRANS. LEVER IN N EU T R A L CONNECT TEST LIG H T | TO BAT. LEAD TERM . TEST L IG H T OFF -------------- ( s t o p ) STARTS ” TEST LIG H T OFF 0 — REPAIR LEAD OR CONNECTOR -(g )TEST LIG H T ON 7 - © - - ~ NO STAR T INSERT TEST LIG H T IN RED B+ WIRE IG N ITIO N SW. - © ” ~ © STARTS 0 — REPAIR OR REPLACE AS NECESSARY ■ © " TEST LIG H T | ON |____ NO STAR T 41 REMOVE A SPARK PLUG WIRE, INSERT EXTENSION AN D PERFORM SPARK TEST NO SPARK USING IN S U LA T E D PLIERS HOLD SPARK PLUG WIRE 1/4 ' A W AY FROM ENG. BLOCK W H ILE C R A N K IN G ENGINE PROBLEM IS N O T IG N IT IO N SYSTEM CHECK EXTENSION SPARK • FU EL SYSTEM •P LU G S •F L O O D E D T R U C K S U P P -S E R V IC E ENGINE E LE C TR IC A L 6Y-21 HIGH ENERGY IGNITION SYSTEM V8 engine STEP SEQUENCE RESULT REMOVE CAP ASSY. STARTS IG N ITIO N OFF V IS U A L L Y INSPECT FOR MOISTURE, DUST CRACKS, BURNS, ETC. DISCONNECT 3-WIRE CONNECTOR REPAIR AS NECESSARY OHMMETER NO START STARTS READS ABOVE 1 OHM (X 1 SCALE) CONNECT OHMMETER REPLACE COIL NO START READS 0 TO 1 OHM (X 1 SCALE) OHMMETER O 7) EITHER TEST READS 6,000 TO 30,000 OHMS STARTS CONNECT OHMMETER BOTH TESTS READ IN F IN IT Y REPLACE COIL NO START REMOVE GREEN & WHITE LEADS FROM MODULE STARTS f LESS TH AN IN F IN IT Y (X 1000 SCALE) CONNECT OHMMETER FROM GROUND TO EITHER LEAD REPLACE COIL (PICK-UP) NO START READS IN F IN IT E (X 1000 SCALE) CONNECT OHMMETER ACROSS 2 LEADS READS 500 TO 1500 OHMS REPEAT STEPS 8 AN D 9 W HILE M OVING VAC. ADVANC E W ITH SCREW D R IV ER . IF R EADING IS S T IL L OK STARTS DOES NOT READ 500 TO 1500 OHMS REPLACE COIL (PICK-UP) NO START REPEAT STEPS 5 TH R U 9 CHECK MODULE WITH TESTER REMOVE AND REPLACE MODULE T RUC K S U P P - SER VIC E 6Y -22 ENGINE E LE C TR IC A L HIGH ENERGY IGNITION SYSTEM V8 engine PROBLEM: engine RUNS ROUGHor CUTS OUT STEP SEQUENCE RESULT <§>-------------------7---------- _ rtSv ( tmJ--------- ~ ~ \< rr — CHECK SPARK PLUGS & PLUG WIRES I RUNSSM00TH -© — M-©— r V IS U A L L Y INSPECT REPAIR AS U FOR MOISTURE, DUST, NECESSARY CRACKS, BURNS, ETC. , M ) EITHER TEST READS 6,000 t o 30,000 OHMS -------- "(0 ) ^ CONNECT OHMMETER BOTH TESTS READ IN F IN IT Y REMOVE GREEN & WHITE LEADS FROM MODULE — RUNS SMOOTH -----TH A N IN F IN IT Y (X 1000 SCALE) REPLACE COIL (PICK-UP) CONNECT OHMMETER FROM oo GROUND TO EITHER READS IN F IN IT E LEAD (X 1000 SCALE) CONNECT OHMMETER ACROSS 2 LEADS © L - §>— RUNS ROUGH REPEAT STEPS 4 A N D 5 W HILE M OVING VAC. AD VANC E W ITH SCREW D R IV E R . IF READING IS S T IL L OK R® x x > READS 500 TO 1500 OHMS I " © -------DOES NOT READ 500 TO 1500 OHMS - — © •RUNS SMOOTH REPLACE COIL (PICK-UP) RUNS ROUGH REPEAT STEPS 1 THRU 5 IF OK ------------------------( s t o p ) CHECK MODULE WITH TESTER IF NOT OK REMOVE AND REPLACE MODULE T R U C K S U P P - S E R VIC E ENG INE E LE C TR IC A L Chart 1 G ENERATO R( 6Y -23 \ PROBLEM: generator light ON engine RUNNING G ENERATO R BELT STEP FUSE B LO C K RESULT SEQUENCE GENERATOR LIGHT OFF REPLACE IF NECESSARY ADJUST TENSION TO 80 LBS. CHECK GENERATOR BELT TURN ENGINE OFF IF ALL LIGHTS OFF GO TO STEP 2 START ENGINE |CHECK FOR CAUSE 'AND REPLACE GAUGES FUSE START ENGINE GENERATOR LIGHT ON (DIM OR BRIGHT) GENERATOR LIGHT ON GO TO STEP 4 TEST LIGHT FULLY BRIGHT CONNECT TEST LIGHT TO NO. 1 TERMINAL TEST LIGHT 1/2 BRIGHT TEST VOLTAGE REGULATOR WITH APPROVED TESTER GROUND GENERATOR "D"SHAPED HOLE GO TO STEP 5 TEST LIGHT 1/2 BRIGHT REPLACE VOLTAGE REGULATOR REPAIR GENERATOR TR U C K S U P P - S ER VIC E 6Y-24 ENG INE ELEC TR IC A L Chart 2 C LU S TE R C O N N EC TO R G E N E R A T O R L IG H T G E N E R A TO R PROBLEM: generator light OFF ignition ON engine NOT RUNNING BULKHEAD C O N N EC TO R STEP SEQUENCE ❖ IGNITION ON FUSE B LO C K CHECK ALL INDICATOR LIGHTS IF ALL LIGHTS OFF RESULT REPLACE GAUGES FUSE IF NEW ■ FUSE -----BLOWS GO TO STEP 2 IF FUSE DOES -----NOT BLOW GO TO STEP 3 LIGHT OFF CHECK FOR PINCHED OR GROUNDED WIRE IN GAUGES CIRCUITS GENERATOR LIGHT ON GO TO STEP 3 REPAIR IF NECESSARY REPLACE GAUGES FUSE GENERATOR LIGHT OFF GENERATOR LIGHT ON GO TO STEP 4 REPAIR OPEN IN NO. 18 PINK WIRE (INDICATOR FEED WIRE) GENERATOR LIGHT OFF GENERATOR LIGHT ON CHECK GENERATOR INDICATOR BULB AND SOCKET ASSY. REPLACE IF NECESSARY ( W J— v s / " GENERATOR LIGHT OFF GO TO STEP 5 GO TO STEP 6 DISCONNECT BROWN/WHITE WIPE GROUND NO. 1 TERMINAL WIRE GENERATOR LIGHT ON GO TO STEP 7 GENERATOR LIGHT OFF T R U C K S U P P - SER VIC E ENG INE E LE C TR IC A L RESULT SEQUENCE STEP 6Y-25 REPAIR GENERATOR 18 BROWN/WHITE REPAIR OPEN C hart 3 G E N E R A T O R L IG H T G ENERATO R C~\ C LU S TE R C O N N EC TO R PROBLEM: generator light ON ignition OFF BU LKHEAD C O N N EC TO R STEP RESULT SEQUENCE GENERATOR LIGHT ON FUSE B LO C K REPAIR SHORT BETWEEN NO. 1 (BROWN) WIRE AND NO. 2 (RED) WIRE DISCONNECT GENERATOR LIGHT OFF T R U C K S UPP - S E R VIC E 6Y-26 ENG INE E LEC TR IC A L c o il(8 ) ( 9) c a rb u re to r G ENERATO R( 1 BATTERY PROBLEM: battery UNDERCHARGED GENERATOR BELT SEQUENCE REPLACE IF NECESSARY ADJUST TENSION TO 80 LBS. DISCONNECT [n e g a t iv e CABLE RESULT CONNECT TEST |LIGHT BETWEEN CABLE & BATTERY .POST MAKE SURE NO ACCESSORIES WERE LEFT ON, IGNITION OFF, DOORS CLOSED, UNDER HOOD LIGHTS DIS­ CONNECTED CHECK GENERATOR BELT TEST LIGHT ON GO TO STEP 3 TEST LIGHT OFF NO DRAIN ON BATTERY TAP CABLE AGAINST POST ^ TEST LIGHT ON TRACE & CORRECT CONTINUOUS DRAIN ON BATTERY TEST LIGHT OFF GO TO STEP 3 TEST LIGHT ON CONNECT VOLTMETER (+) TERMINAL AND GROUND RECONNECT NEGATIVE CABLE CONNECT JUMPER (-) TERMINAL AND GROUND ( ON H.E.I. DISCONNECT FEED WIRE) IF READING IS WITHIN .5 VOLT OF VOLTAGE AT GEN IF READING IS NOT WITHIN .5 VOLT OF READING AT GEN. CHECK FOR BATTERY CABLE AND STARTER TO DELCOTRON CIRCUIT RESISTANCE CHECK VOLTAGE ACROSS POST WHILE CRANKING REPLACE BATTERY GO TO STEP 6 NEEDLE ABOVE 9.0 VOLTS CRANK ENGINE LONG ENOUGH FOR STABILIZED NEEDLE BELOW 9.0 VOLTS READING TEST BATTERY USING BATTERY LOAD TEST PROCEDURE GO TO STEP 4 BATTERY OK CHARGE AS SPECIFIED BY TEST BATTERY NOT OK GO TO STEP 6 T R U C K SUP P - S E R VIC E ENGINE E LE C TR IC A L STEP RESULT SEQUENCE CONNECT VOLTMETER ACROSS BATTERY PLACE CARB. ON HIGH STEP FAST IDLE CAM DISCONNECT COIL JUMPER OR RECONNECT HEI FEED WIRE START ENGINE DO NOT TOUCH ACCELERATOR PEDAL HEADLIG HTS-HllW f TURN ON ACCESSORIES 6Y-27 IF VOLTAGE READS LOWER TH AN PREVIOUS READING GO TO STEP 9 IF VOLTAGE READS HIGHER THAN PREVIOUS READING GO TO STEP 8 A/C - HI RADIO BLOWER TYPE DEFOGGER CHECK VOLTAGE READING NOTE: IF NOTHING HAS BEEN FOUND RE-EDUCATE OWNER ON EXCESSIVE IDLING, SLOW OR SHORT DISTANCE DRIVIN G WITH A L L ACCESSORIES ON. TR U C K S U P P - S E R V IC E 6Y-28 ENGINE ELEC TR IC A L Chart 5 PROBLEM: battery OVERCHARGED (uses too much water) STEP SEQUENCE RESULT BATTERY OK BATTERY NOT OK REPLACE BATTERY PLACE CARB. ON HIGH STEP FAST IDLE CAM CONNECT VOLTMETER ACROSS BATTERY START ENGINE DO NOT TOUCH ACCELERATOR PEDAL CHECK VOLTAGE READING TURN O F F A L L ACCESSORIES W AIT U N TIL UPPER RADIATOR IN LET AND IS HOT GO TO STEP 3 READING IS 12.5 to 15.5 READING IS NOT 12.5 to 15.5 VOLTMETER NEEDLE STOPS ------ 0 PERFORM NEXT TWO STEPS 4 & 5 GO TO STEP 5 IF GROUNDED CHECK FOR GROUNDED BRUSH LEAD CLIP________ REPAIR GRQUND IF NOT TEST VOLTAGE GROUNDED REGULATOR W ITHX _____________ APPROVED TESTER GO TO STEP 5 GO TO STEP 5 REPLACE VOLTAGE REGULATOR REPLACE ROTOR AND VOLTAGE REGULATOR CHECK FOR SHORTED FIELD WINDINGS OHMMETER (SEE SERVICE M AN U AL FOR SPECIFICATIONS) REPLACE VOLTAGE REGULATOR T R U C K SUPP • SER VIC E S E C T IO N 7 M CLUTCHES AND MANUAL TRANSM ISSIONS C O N T E N T S OF T H IS S E C TIO N Clutch C o n tro ls................................................................................... M anual Transmissions........................................................................ 7M-1 7M-3 CLUTCH CONTROLS GENERAL DESCRIPTION The clutch operating controls for "G " models (fig. IT) are a mechanical type consisting of a pendant type pedal, return spring, pedal pull rod, cross-shaft, fork push rod, clutch fork and throw out bearing. The pedal pull rod is routed vertically from the clutch pedal lever down through the toe panel to the cross shaft. W hen the pedal is depressed, the pedal pull rod moves rotating the cross shaft, pushing the clutch fork rod rearw ard and pivoting the clutch fork. This action moves the throw out bearing against the clutch release fingers, releasing the clutch. TR U C K S UPP - S E R V IC E 7 M -2 C LU TCH A N D M A N U A L T R A N S M IS S IO N S F ig . 1 T -C lu tc h L in k a g e A s s e m b ly - G M o d e ls T R U C K S UPP - SER VIC E C LU TCH A N D M A N U A L T R A N S M IS S IO N S 7 M -3 MANUAL TRANSMISSIONS SERVICE OPERATIONS The service procedures for the Trem ec 3 speed will be the same as 3 speed listed in the 1974 Service Manual. 3. Remove skid plate and crossmember supports as necessary. 4. Disconnect rear prop shaft from transfer case and tie up away from work area. 5. Disconnect front prop shaft from transfer case and tie up shaft away from work area. 6. Disconnect shift lever rod from shift rail link. On full time 4 wheel drive models, disconnect shift levers at transfer case. 7. Support transfer case and remove bolts attaching transfer case to transmission adapter. 8. Move transfer case to rear until input shaft clears adapter and lower assembly from vehicle. Installation 1. Support transfer case in suitable stand and position case to transmission adapter. Install bolts attaching case to adapter and torque to 45 ft. lbs. 2. Remove stand as required and install bolts attaching transfer case to frame rail. Bend lock tabs after assembly. 3. Install connecting rod to shift rail link or connect shift levers to transfer case, as applicable. 4. Connect front prop shaft to transfer case front output shaft. 5. Connect rear prop shaft to transfer case rear output shaft. 6. Install crossmember support and skid plate, if removed. 7. Connect speedometer cable, back-up lamp and TCS switch. TRANSFER CASE REPLACEMENT (Figs. 1Q-2Q) 8. Fill transfer case to proper level with lubricant specified in the lubricant section of the Truck Chassis Service Manual. 9. Lower and remove vehicle from hoist. Removal CAUTION: Check and tighten all bolts to specified 1. Raise and support vehicle on hoist. D rain transfer case. torques. 2. Disconnect speedometer cable, back-up lamp and TCS switch. NOTE: Before connecting prop shafts to companion flanges be sure locknuts are torqued to specifications. • . T R U C K S U P P - S E R VIC E 7 M -4 C LU TCH A N D M A N U A L T R A N S M IS S IO N S N O T E : Install B o o t p rio r to in sta lla tio n o f N u t & Knob. N O T E : No insulation to be installed under Retainer. N O TE : W ith trans case in " N e u tra l" p o sitio n , align In d ic a to r Plate to center o f S h ift Lever. N O T E : No insulation to be installed under retainer. N O T E : W ith trans case in 2 wheel " H i " p o sitio n , align in d ic a to r plate to center o f s h ift lever. N O TE : Do n o t lub ricate b o lt threads o n ly shank groove. M O D E L 203 M O D E L 2 05 F ig . 2 Q - T r a n s fe r C ase C o n tro ls T R U C K SUP P ■ S E R VIC E S E C T IO N 7 A AUTOMATIC TRANSMISSION C O N T E N T S OF T H IS S E C T IO N Turbo H ydra-M atic 350 Transm ission........................................... Turbo H ydra-M atic 400/475 Transm ission.................................. 7A -1 7A-5 TURBO HYDRA-MATIC 350 TRANSMISSION IN D E X G eneral D escription.......................................................... 7A-1 Vacuum M odulator A ssem bly...................................... 7A-1 M aintenance and A dju stm en ts....................................... 7A-2 Transmission F lu id.......................................................... 7A-2 Draining and Refilling Transmission.........................7A-2 Shift C ontrols......................................................................7A-2 Column Shift Linkage - G Series.................................7A-2 D etent Downshift Cable...................................................7A-2 Manual Shaft, Range Selector Inner Lever and Parking Linkage A ssem blies................................ 7A-3 Service O perations..............................................................7A-3 Transmission Replacem ent............................................ 7A-3 Diagnostics.......................................................................... 7A-4 Oil Pressure C h eck ........................................................ 7A 4 Spring Tension Comparison C heck............................ 7 A 4 GENERAL DESCRIPTION VACUU M MODULATOR ASSEMBLY (FIG. 1G) The engine vacuum signal is provided by the vacuum modulator, which consists of a diaphragm and one spring. The external spring applies a force which acts on the m odulator valve. This force acts on the m odulator valve so that it increases m odulator pressure. Engine vacuum acts in the opposite direction to decrease modulator, or low engine vacuum, high m odulator pressure. High engine vacuum, and low modulator pressure. F ig . 1 G ~ V a c u u m M o d u la to r A s s e m b ly TR U C K SUP P - S ER VIC E 7 A -2 A U T O M A T IC T R A N S M IS S IO N MAINTENANCE AND ADJUSTMENTS TRANSM ISSIO N FLUID Draining and Refilling Transmission The oil pan should be drained and the strainer, cleaned every 30,000 miles and fresh fluid added to obtain the proper lever on indicator. For vehicles subjected to heavy city traffic during hot weather, or in commercial use, when the engine is regularly idled for prolonged periods or when vehicle is used for towing the oil pan should be drained and the strainer cleaned every 15,000 miles. P. WASHER GROMMET, COLUMN SHIFT LEVER. BUSHING. CLAMP E L. WASHER NUT F COLUMN ASSEMBLY SWIVEL D ROD A TRANS LEVER C D rain fluid immediately after operation before it has had an apportunity to cool. TRANSMISSION ( 7 ) RETAINER GROMMET SHAFT ASSEMBLY B W ARNING: Transmission fluid tem perature GROMMET can exceed 350F. F ig . 2 G --C o lu m n S h ift L in k a g e - G S e rie s SHIFT CONTROLS Column Shift Linkage - G Series (Fig. 2G) 1. The shift tube and lever assembly must be free in the mast jacket. 2. Set transmission lever (C) in "neutral" position by one of the following optional methods. NOTE: Obtain "neutral" position by moving transmission lever (C) counter-clockwise to "L I" detent, then clockwise three detent positions to "neutral" or obtain "neutral" position by moving transmission lever (C) clockwise to the "park" detent then counter-clockwise two detents to "neutral". 3. Set the column shift lever in "neutral" position. This is obtained by rotating shift lever until it locks into mechanical stop in the column assembly. clutches. Partial engagement o f the clutches with sufficient pressure to cause apparent normal operation of the vehicle will result in failure o f the clutches or other internal parts after only a few miles of operation. DETENT DO W N SHIFT CABLE (Figs. 3G and 4G) Removal 1. Push up on bottom of snap-lock and release lock and detent downshift cable. 2. Disconnect cable from carburetor lever. 3. Compress locking tabs assembly from bracket. and disconnect snap-lock 4. Remove clamp around filler tube, remove screw and washer securing cable to transmission and disconnect detent downshift cable. Installation NOTE: Do not use indicator pointer as a reference to position the shift lever. 1. Install new seal on detent downshift cable lubricant seal with transmission fluid. 4. A ttach rod (A) to shaft assembly (B) as shown (fig. 2G). 2. Connect transmission end of detent downshift cable and secure transmission case with bolt and washer tightened to 75 inch pounds. 5. Slide swivel (D) and clamp (E) onto rod (A) align the column shift lever and loosely attach as shown. 6. Hold column lever against "neutral" stop "park" position side. 7. Tighten nut (F) to 18 foot pounds. 8. Readjust indicator needle if necessary to agree with the transmission detent positions. 9. Readjust neutral start switch if necessary to provide the correct relationship to the transmission detent positions. CAUTION: Any inaccuracies in the above adjustments may result in premature failure o f the transmission due to operation without controls in full detent. Such operation results in reduced oil pressure and in turn partial engagement o f the affected 3. Route cable in front of filler tube and install clamp around filler tube, m odulator pipe and detent downshift cable. Locate clamp approximately 2 inches above filler tube bracket. 4. Pass cable through bracket and engage locking tabs of snap-lock on bracket. 5. Connect cable to carburetor lever. Adjustment With snap-lock disengaged, position carburetor to wide open throttle (W .O.T.) position and push snap-lock downward until top is flush with rest of cable. T R U C K SUP P - S E R VIC E A U T O M A T IC T R A N S M IS S IO N 7A -3 V -8 EN G IN E SNAP LO C K L-6 EN G IN E C A U T IO N : Flexible com ponents (hoses, wires, conduits, etc) m ust n o t be routed w ith in 2 inches o f m oving parts o f accelerator linkage fo rw a rd o f the Bracket unless ro u tin g is positive ly co n tro lle d . V IE W A F ig . 3 G --D e te n t D o w n s h ift C a b le - G S e rie s M A N UAL SHAFT, RANGE SELECTOR INNER LEVER AND PARKING LINKAGE ASSEMBLIES The procedure for removal and installation remains the same with the addition of this notation: NOTE: Before installing the propeller shaft, liberally lubricate splines of the transmission yoke with a Lithium soap base lubricant. The lubricant should seep from the vent hole (rear cap of yoke) when installing yoke on transmission output shaft. It is essential that the vent hole is not obstructed. TRANSM ISSIO N REPLACEMENT The procedure for transmission replacement remains the same with the addition of this note: NOTE: If necessary, the catalytic converter may have to be disconnected to provide adequate clearance for transmission removal. This procedure will include removal of the converter support bracket. TRUC K S UPP - S ER VIC E 7A -4 A U T O M A T IC T R A N S M IS S IO N F ig . 4 G ~ D e te n t D o w n s h ift C a b le CK a n d P S e rie s DIAGNOSIS OIL PRESSURE CHECK SPRING TENSION CO M PARISO N CHECK While vehicle is stationary (service brake on), engine speed set to 1200 rpm, transmission oil pressure gauge attached, and vacuum m odulator tube disconnected the transmission to line pressure tap should read 167 psi in drive, 166 psi in LI or L2, and 254 psi in reverse for the 350 V-8. Using tool J-2466, as shown in Figure 5G, compare the load of a known good m odulator with the assembly in question. While vehicle is stationary (service brake on), engine speed set to m aintain 12 inches hg. absolute manifold pressure, transmission oil pressure gauge attached, and vacuum modulator tube connected, the transmission should read 85 psi in drive. 105 psi in LI or L2, and 129 psi in reverse for the 350 V-8. a. Install the m odulator that is known to be acceptable on either end of the tool. b. Install the m odulator in question on the opposite end of the tool. c. Holding the m odulators in a horizontal position, bring them together under pressure until either m odulator sleeve just touches the tool. The indicator in the gage will show white if the m odulator TRUC K SUP P - SER VIC E A U T O M A T IC T R A N S M IS S IO N 7A -5 acceptable. A non-conforming m odulator will cause the indicator to shift, thus showing blue. If white does not appear, the m odulator in question should be replaced. HOLD MODULATORS IN A HOR IZO NTAL PO SITIO N, AS S H O W N , BRING THEM SLOWLY TOGETHER UNDER PRESSURE F ig . 5 G --S p rin g T e n s io n C o m p a ris o n TURBO HYDRA-MATIC 4 0 0 /4 7 5 TRANSMISSION IN D E X M aintenance and A djustm ents......................................................... .. 7A-1 Transmission F lu id ........................................................................... .. 7A-1 Draining and Refilling Transm ission....................................... .. 7A-1 D etent Downshift S w itch................................................................ .. 7A-1 R ear Seal............................................................................................. .. 7A-1 Service O perations................................................................................. 7A-2 Transmission R eplacem ent................................................................ 7A-2 MAINTENANCE AND ADJUSTMENTS TRAN SM ISSIO N FLUID DETENT D O W N SHIFT SW ITCH Draining and Refilling Transmission 1. Install switch as shown in Figure 1L. The oil pan should be drained and filter replaced every 30,000 miles and fresh fluid added to obtain the proper level 2. After installing the switch, press the switch plunger as far forward as possible. This presets the switch for adjustment. The switch will then adjust itself with the first idle open throttle application of the accelerator pedal. on indicator. For vehicles subjected to heavy city traffic during hot weather, or in commercial use, when the engine is regularly idled for prolonged periods or when vehicle is used for towing, oil pan should be drained and filter replaced REAR SEAL every 15,000 miles. Removal D rain fluid immediately after operation before it has had an ooportunity to cool. 1. Remove propeller shaft. 2. Pry seal out with screw driver. InstallationWARNING: Transmission fluid tem perature can exceed 350°F. ,4// M o d e ls E x c e p t CL 1. Use a non-hardening sealer on outside of seal body; and using Tool J-21359, drive seal in place. T R U C K SUP P - S E R V IC E 7 A -6 A U T O M A T IC T R A N S M IS S IO N 2. Re-install propeller shaft. M o d e l CL 1. Use a non-hardening sealer on outside of seal body; and using Tool J-24057 drive seal in place. 2. Re-install propeller shaft. TRANSM ISSIO N REPLACEMENT The procedure for transmission replacement remains the same with the addition of this note: NOTE: If necessary, the catalytic converter may have to be disconnected to provide adequate clearance for transmission removal. This procedure will include removal of the converter support bracket. F ig . 1 L - D e te n t D o w n s h ift S w itc h TR U C K S U P P -S E R V IC E S E C T IO N 8 FUEL TANK AND EXHAUST SYSTEM C O N T E N T S OF T H IS S E C TIO N Fuel T an k .............................................................................................. Exhaust System .................................................................................... 8-1 8-2 FUEL TANK Refer to the 1974 Light D uty Truck Service M anual for servicing of the fuel tank and evaporation control system with the following exception: COMPONENT PART REPLACEMENT P MODELS AND 1 TON CHASSIS (FRAME) MOUNTED TANKS Refer to the 1974 Service M anual for 30 gallon fuel tank m ounted on a P20 or P30 model. Refer to Figure 1 for a 50 gallon fuel tank m ounted on a P30 model. Removal and Installation 1. D rain tank. 2. Remove filler neck. 3. Disconnect gauge unit fuel line and wiring. Ignition switch must be in O F F position. 4. Remove bolts attaching tank supports to frame. 5. Remove tank complete with m ounting brackets and support straps. 6. Remove tank from brackets and support straps, if necessary. 7. To install, reverse the removal procedures. Replace all anti-squeak material. FUEL FEED AND VAPOR PIPES Fuel pipes are secured to the underbody with clamp and screw assemblies. Flexible hoses are located at fuel tank fuel, vapor and return lines and fuel pump. The pipes should be inspected occasionally for leaks, kinks or dents. If evidence of dirt or foreign material is found in carburetor, fuel pum p or pipes, pipe should be disconnected and blown out. D irt or foreign m aterial may be caused by a damaged or om itted fuel strainer in fuel tank. Replacement If replacement of a fuel feed pipe, vapor pipe or return pipe is required, use only double wrap and brazed steel tubing meeting GM Specification 123M or its equivalent. Under no condition use copper or aluminum tubing to replace steel tubing. Those materials do not have satisfactory fatique durability to w ithstand normal vehicle vibrations. Repair 1. Do not use fuel hose for pipe repair within 4 inches of any part of the exhaust system. 2. In repairable areas, cut fuel hose 4 inches longer than the portion of pipe removed. Use only hose stated for T R U C K SUPP - S E R VIC E 8-2 FUEL T A N K A N D E X H A U S T S Y S T E M fuel usage by the m anufacturer. will not be longer than 10 inches. If more than a 6-inch length of pipe is removed, use a combination of steel pipe and hose so that hose lengths 3. The fuel hose should extend 2 inches on each pipe and be clamped at each end. Pipes must be properly secured to the frame to prevent chafing. EXHAUST SYSTEM GENERAL DESCRIPTION For alignment purposes, the muffler outlet flange is notched and mates to a welded tab located on the outside diameter of the tailpipe. The exhaust pipes and muffler use locater tabs for alignment. monoxide pollutants from the exhaust gas stream. The converter contains beads which are coated with a catalytic material containing platinum and palladium. The CIO with light duty emissions (except 454 V8) and G10 vehicles have an exhaust system with a catalytic converter between the front exhaust pipe and the rear exhaust pipe. Periodic maintenance of the exhaust system is not required; ho wever, if the car is raised for other service, it is advisable to check the general condition of the catalytic converter, pipes and mufflers. The catalytic converter is an emission control device added to the exhaust system to reduce hydrocarbon and carbon CAUTION: When jacking or lifting vehicle from The catalytic converter requires the use o f unleaded fuel only. frame side rails, be certain lift pads do not contact catalytic converter as damage to converter will result. COMPONENT PART REPLACEMENT GENERAL Exhaust System Pipes and Resonators Rearward of the M ufflers M ust Be Replaced W henever A New M uffler Is Installed. NOTE: W hen a muffler is replaced use sealing compound at the clamped joint to prevent leaks. Truck exhaust systems vary according to series and model designation. Series 10-30 trucks use a split-joint design system in which the exhaust pipe-to-muffler are clamped together and muffler-to-tailpipe connections are welded together. All mufflers and tailpipes are welded assemblies (no clamps) in 1976. NOTE: All 10-20-30 series exhaust systems are aluminized steel except: (1) "C" Series exhaust pipes and (2) stainless steel exhaust pipes on vehicles equipped with underfloor catalytic converters. Always use correct replacement parts when servicing these systems. W hen installing a new exhaust pipe or muffler and tailpipe, on any model, care should be taken to have the correct alignment and relationship of the components to each other. Particular care should be given to the installation of the exhaust pipe and crossover pipe assembly on V-8 engine single exhaust systems. Incorrectly assembled parts of the exhaust system are frequently the cause of annoying noises and rattles due to improper clearances or obstructions to the normal flow of gases. Leave all clamp bolts and muffler bolts loose until all parts are properly aligned and then tighten, working from front to rear. Exhaust system hangers, hanger brackets, and clamps which are damaged should be replaced to m aintain proper exhaust system alignment. NOTE: When reinstalling exhaust pipe to manifold, always use new packings and nuts. Be sure to clean manifold stud threads with a wire brush when installing the new nuts. CONVERTER HEAT SHIELD C 10 Model Refer to Figure 2 for converter heat shield. CATALYTIC CONVERTER (FIGS. 3 and 4) Cl Cl and G10 Model Removal 1. Raise vehicle on hoist. T R U C K S U P P - S ER VIC E FUEL T A N K A N D E X H A U S T S Y S T E M 8-3 2. Remove clamps at front and rear of converter. 3. Cut converter pipes at front and rear of converter and remove converter. 4. On CIO models, remove converter-to-transmission. support 5. Remove converter pipe-to-front-exhaust converter pipe-to-rear exhaust pipe. attaching pipe and Installation 1. W ith sealer on exhaust pipes, install pipes into converter. 2. On CIO model, loosely connect support attaching converter-to-transm ission. 3. Install new "U" bolts and clamps at front and rear of converter. 4. Clamp on vibrator J-25077-1 (Fig. 7). 4. Check all clearance and tighten clamps and upport. 5. Install empty catalyst container to converter (Fig. 8). 5. Lower vehicle and remove from hoist. 6. Disconnect air supply to aspirator and connect air supply to vibrator. Catalyst will now drain from the converter into the empty container. Catalyst Removal If necessary, the catalyst in the converter can be replaced on the truck with Tool No. J-25077. 1. Install aspirator J-25077-2 (Fig. 5). 2. Connect air supply line to aspirator to create a vacuum in the converter to hold beads in place when fill plug is removed. 3. Remove converter fill plug with 3/4" hex wrench or Tool J-25077-3 and 4 (Fig. 6). 7. W hen all the catalyst has been removed from the converter, disconnect air supply to vibrator and remove container from the converter. 8. Discard used catalyst. Catalyst Installation 1. Fill container with approved replacement catalyst. 2. Install fill tube extension to the fixture J-25077-1 (Fig. 9 ). 3. Connect air supply to aspirator and vibrator. W ARNING: To prevent serious burns, avoid contact with hot catalyst. 4. A ttach catalyst container to the fixture. 5. After the catalyst stops flowing, disconnect air supply to the vibrator. TRUC K SUP P - SER VIC E 8-4 FUEL T A N K A N D E X H A U S T S Y S T E M Bottom Cover If, for any reason, the bottom cover of the converter is torn or severely damaged, it can be replaced with a repair kit. Bottom Cover Replacement 1. Remove bottom cover by cutting close to the bottom outside edge, Figure 10 and 11. Do not remove the fill plug. The depth of the cut must be very shallow to prevent damage to the inner shell of the converter. AIR SUPPLY LINE 2. Remove insulation (Fig. 12). J-25077-2 3. Inspect inner shell of the converter for damage. If there is damage in the inner shell, the converter assembly must be replaced (Fig. 13). 4. Place new insulation in the replacement cover. Apply sealing compound, all around the cover after the insulation is in position. Apply extra sealer at the front and rear opening for the pipes (Fig. 14). F ig . 5 —In s ta llin g A s p ir a t o r 5. Install replacement cover on converter (Fig. 14). 6. Install cover retaining channels on both sides of the converter (Fig. 15). 7. A ttach 2 clamps over retaining channels at each end of the converter (Fig. 16). Fig . 6 - R e m o v in g F ill P lu g 6. Remove vibrator and check that catalyst has filled converter flush with fill plug hole. A dd catalyst if required. 7. Apply an anti-seize com pound to the fill plug; install and tighten to 5 0 pound feet. J-25077-1 F ig . 7 — In s ta llin g V ib r a t o r TR U C K SUP P - SER VIC E FUEL T A N K A N D E X H A U S T S Y S T E M 8-5 J -2 5 0 7 7 -1 A IR SUPPLY LINE CA TA LYST C O N T A IN E R F ig . 8 - C o n ta in e r In s ta lle d o n V ib r a t o r F ig . 9 - F ill T u b e E x te n s io n Fig. 1 0 -R e m o v in g B o tto m C o v e r F ig . 1 1 -R e m o v in g B o tto m C o v e r TRUC K S UPP - S ER VIC E 8-6 FUEL T A N K A N D E X H A U S T S Y S T E M Fig. 1 2 - C a ta ly tic C o n v e rte r In s u la tio n F ig . 1 3 - C a ta ly tic C o n v e rte r In n e r S h e ll IN S U L A T IO N S E A L IN G COMPOUND R E T A IN IN G C H A N N E L F ig . 1 5 —1n s ta llin g B o tto m C o v e r R e ta in in g C h a n n e ls F ig . 1 4 —In s t a llin g B o tto m C o v e r R e p la c e m e n t TRUC K SUP P - SER VIC E FUEL T A N K A N D E X H A U S T S Y S T E M 8-7 C LA M P Fig. 1 6 - ln s t a llin g B o tto m C o v e r C la m p s TRUC K SUP P - S E R VIC E 8-8 FUEL T A N K A N D E X H A U S T S Y S T E M DIAGNOSIS EXHAUST SYSTEM CONDITION L e akin g E xh a u st Gases POSSIBLE CAUSE Leaks a t pip e jo in ts . CORRECTION T ig h te n U -b o lt nuts a t leakin g jo in ts to 3 0 fo o t-p o u n d s . D am aged o r im p ro p e rly R ep lace seals o r p ackin g in stalled seals or p ackin g. as necessary. Loose e x h au st p ip e h e at tu b e R ep lace seals o r p a ckin g as ex te n s io n co n n ectio n s . re q u ire d . T ig h te n stud nuts o r b o lts to s p e cificatio n s. B urn e d or rusted o u t ex h au st R ep lace h e at tu b e e x ten sio n s pip e he at tu b e ex ten sion s. as re q u ire d . T ig h te n cla m p s a t leaking E xh a u st Noises Leaks a t m a n ifo ld o r p ip e c o n n ectio n s . c o n n e c tio n s to sp ecified to rq u e . R ep lace gasket o r packin g as re q u ire d . B urned o r b lo w n o u t m u ffle r . R ep lace m u ffle r assem bly. B urn e d o r rusted o u t ex h au st pipe. R ep lace e x h a u s t p ip e. E x h a u s t p ip e leakin g a t m a n ifo ld flang e. T ig h te n a tta c h in g b o lts nuts to 17 f o o t ­ pounds. E x h a u s t m a n ifo ld crack ed o r b ro k e n . R ep lace m a n ifo ld . Leak b e tw e e n m a n ifo ld and c y lin d e r head. T ig h te n m a n ifo ld to c y lin d e r head stud nuts o r b o lts to s p ecificatio n s. Loss o f engine p o w e r a n d /o r D islodged tu rn in g tu bes and or in te rn a l ra ttle s in m u ffle r . b a ffle s in m u ffle r . Loss o f engine p o w e r. Im p lo d in g (in n e r w a ll collapse) R ep lace m u ffle r . R ep lace e x h a u s t p ip e . o f e x h au st pip e (C T r u c k ) TR U C K SUP P - SER VIC E FUEL TANK AND EXHAUST SYSTEM 8-9 SPECIAL TOOLS 1. J-2507 7-1 V ib r a t o r — Include C atalyst C o n tain er an d Fill Tube Extension 2. J -2 5 0 7 7 -2 A sp irator F ig . 1 S T -S p e c ia l T o o ls TR U C K S U P P - SER VIC E n S E C T IO N 9 STEERING The following caution applies to one or more steps in the assembly procedure of components in this portion of the manual as indicated at appropriate locations by the terminology "See Caution on Page 1 of this Section". C A U T I O N : THIS FASTENER IS A N IMPORTANT A TTACHING PART IN THAT IT COULD AFFECT THE PERFORMANCE OF VITAL COMPONENTS AN D SYSTEMS, AND/OR COULD RESULT IN MAJOR REPAIR EXPENSE. IT MUST BE REPLACED WITH ONE OF THE SAME PART NUMBER OR WITH A N EQUIVALENT PART IF REPLACEMENT BECOMES NECESSARY. DO NOT USE A REPLACEMENT PART OF LESSER QUALITY OR SUBSTITUTE DESIGN TORQUE VALUES MUST BE USED AS SPECIFIED DURING REASSEMBL Y TO ASSURE PROPER RETENTION OF THIS PART. IN D E X General D escription................................................................. 9-1 M aintenance and Adjustm ents.............................................. 9-1 Power Steering Pum p Belt A djustm ent........................... 9-1 Power Steering G e a r.............................................................9-1 Service O perations................................................................... 9-3 Steering W heel........................................................................9-3 Directional Signal Switch.....................................................9-3 Steering L inkage................................................................ 9-3 Idler A rm ........................................................................... 9-3 Tie R o d s..............................................................................9-4 Power Steering Pum p.......................................................9-4 Power Steering Hoses....................................................... 9-4 Bleeding Power Steering System s..................................9-4 Special Tools......................................................................... 9-12 GENERAL DESCRIPTION All 1976 truck models have basically the same steering systems as the 1974 models. All service procedures outlined in the 1974 Light D uty Truck Service M anual apply as well to the 1976 truck steering systems except the following procedures. MAINTENANCE AND ADJUSTMENTS POWER STEERING PUMP BELT ADJUSTM ENT The effect of improperly adjusted worm thrust bearings or Power steering belt adjustment for 1976 truck models is identical to the procedure outlined in the 1974 Light Duty Truck Service Manual, Section 9, Page 9-27 with the exception of a 1/2" spuare hole in the support bracket on some engines to aid in belt adjustment as shown in Fig. 8. Use a 1/2" drive ratchet or breaker bar handle, inserted in the hole to assist on obtaining proper belt adjustment. an improperly adjusted over-center preload could cause a POWER STEERING GEAR Adjustment of the power steering gear in the vehicle is discouraged because of the difficulty involved in adjusting the worm thrust bearing preload and the confusing effects of the hydraulic fluid in the gear. The steering gear adjustment is made only as a correction and not as a required periodic adjustment. handling stability complaint. To properly adjust the power steering gear, the assembly MUST be removed from the vehicle and adjustments per­ formed as outlined in the 1974 Overhaul Manual, Section 9. For removal of the power steering gear assembly follow the procedure as outlined under "Power Steering Gear", in the 1974 Light D uty Truck Service Manual, Section 9. T R U C K S U P P - SER VICE 9-2 STEERING Key No. 1 2 3 4 5 Part Name 67 - COLUM N ASM HOUSING ASM RACK ASM SPRING SECTOR SHA FT CLIP 8 - S W IT C H 9 10 11 12 - BEA RING - WASHER - SCREW (4) - R E T A IN IN G RING 13 - NU T 14 - COVER ASM (SHIPPED SE PA R A TELY) 15 16 17 18 - R ING - LOCK - CAM ASM - SPRING SCREW (3) Key No. Part Name 20 21 - S W IT C H A S M P R O T E C T O R W IR E 22 - H O U S IN G 23 24 25 - CUP B O LT ASM W ASHER 26 27 28 29 - G ATE - SC REW (2) - JA C K E T ASM - S W IT C H A S M , IG N IT IO N Key No. Part Name 39 - W ASHER 40 41 42 - S P R IN G ADAPTER R E T A IN E R 43 - B E A R IN G 44 45 - R IN G S H A F T ASM C L IP S H A F T ASM C O U P L IN G A S M SC R E W (2) 46 47 48 - 31 - B OW L A S M 49 - B OLT 32 - S P R IN G 33 34 - BOWL SHROUD 50 51 - NUT R IN G 35 - B E A R IN G 52 53 54 - S P R IN G B E A R IN G (2) A B R A S IO N S H IE L D 30 - 36 - JA C K E T ASM 37 - S E A L -D A S H 55 - BO LT 38 - TU B E ASM 56 - NUT Fig. 1 -T y p ic a l S ta n d a rd C olu m n T R U C K S U P P - SER VIC E S TEERING 9-3 SERVICE OPERATIONS STEERING COLUMN COVER Fig. 3--R e m o v in g Lock P late C over 7. Place cover on the lockplate and snap into position. STEERING LINKAGE STEERING WHEEL (Fig. 2) Removal The service procedures for the removal and installation of the steering wheel are identical to the procedures outlined in the 1974 Light D uty T ruck Service M anual, Section 9 with the exception of the addition of a steering wheel snap ring as shown in Figure 2. Refer to Page 9-29 of the 1974 Light D uty Truck Service M anual for proper removal procedure. W hen removing the steering wheel, remove the snap ring as Step 3 in the removal procedure. Installation W hen installing the steering wheel, replace the snap ring after tightening the steering wheel nut to proper torque specifications. DIRECTIONAL SIGNAL SW ITCH Standard Column The service procedure for the removal and installation of the directional signal switch is identical to the 1974 vehicle with the exception of the lock plate cover as shown in Figure 3. Removal procedure, step num ber 3, for standard steering columns should read: 3. Position screwdriver blade into cover slot (fig. 3). Pry up and out to free cover from lock plate. Installation Procedure, step 7 for standard column should read: All service procedure for the 1976 steering linkage are identical with those outlined in the 1974 Light Duty Truck Service Manual, Section 9. Figure 4 shows the latest linkage used on the G-Series truck and the P-Series, M otor Home models. IDLER ARM Use of the proper diagnosis and checking procedure is essential to prevent needless replacement of good idler arms. The proper checking procedure is as follows: 1. Raise the vehicle in such a manner as to allow the front wheels to rotate freely and the steering mechanism freedom to turn. Position the wheels in a straight ahead position. 2. Using a push pull type spring scale located as near the relay rod end of the idler arm as possible, exert a 25 lb. force upward and then downward while noticing the total distance the end of the arm moves. This distance should not exceed 1/8 inch (Figure 3A). It is necessary to ensure that the correct load is applied to the arm since it will move more when higher loads are applied. It is also necessary that a scale or ruler be rested against the frame and used to determine the am ount of movement since observers tend to over-estimate the actual movement when a scale is not used. The idler arm should always be replaced if it fails this test. NOTE: Jerking the right front wheel and tire assembly back and forth thus causing an up and down movement in the idler arm is not an acceptable method of checking since there is no control on the am ount of force being applied. TR U C K S UPP - S ER VIC E 9-4 STEERING 3. Fill reservoir. Bleed pump by turning pulley backward (counter-clockwise as viewed from the front) until air bubbles cease to appear. 4. Install pump belt over pulley. 5. Tension belt as outlined under "Pump Belt Tension A djustm ent". 6. Bleed as outlined under "Bleeding Power Steering System". POWER STEERING HOSES When servicing the power steering hoses be sure to align the hoses in their correct position as shown in Figs. 13-28. It is im portant that the power steering hoses be installed correctly. Hoses installed out of position may be subjected to chafing or other abuses during sharp turns. Do not twist hoses unnecessarily during installation. CAUTION: Do not start engine with any power steering hose disconnected. BLEEDING POWER STEERING SYSTEMS F ig 3 A - C h e c k in g Id le r M o v e m e n t Caution should be used in assuming shimmy complaints are caused by loose idler arms. Before suspecting suspension or steering components, technicians should eliminate shimmy excitation factors, such as dynamic imbalance, run-out or force variation of wheel and tire assemblies and road surface irregularities. TIE RODS Service procedures for the 1976 tie rod assemblies are identical to those outlined in the 1974 Light D uty Truck Service Manual, Section 9. Figure 5 shows the updated tie rod clamp relationships for 1976 models. POWER STEERING PUMP (Figs. 6-12) Removal 1. Disconnect hoses at pump. When hoses are disconnected, secure ends in raised position to prevent drainage of oil. Cap or tape the ends of the hoses to prevent entrance of dirt. On models with remote reservoir, disconnect reservoir hose at pump and secure in raised position. Cap hose pump fittings. 2. Install two caps at hose fittings to prevent drainage of oil from pump. 3. Loosen bracket-to-pum p m ounting nuts. When a power steering pump or power gear has been installed, the air that has entered the system must be bled out before the vehicle is again operated. If air is allowed to remain in the power steering fluid system, noisy and unsatisfactory operation of the system will result. Bleed air from the hydraulic system as follows: NOTE: W hen power steering fluid is added to power steering system, only clean new power steering fluid should be used (G M #1050017). 1. Fill oil reservoir to proper level and let oil remain undisturbed for at least two minutes. 2. Start engine and run momentarily. 3. A dd oil, if necessary. 4. Repeat above procedure until oil level remains constant after running engine. 5. Raise front end of vehicle so that wheels are off the ground. 6. Turn the wheels (off ground) right and left, lightly contacting the wheel stops. 7. A dd oil if necessary. 8. Lower the vehicle and turn wheels right and left on the ground. 9. Check oil level and refill as required. 10. If oil is extremely foamy, allow vehicle to stand a few minutes with engine off and repeat above procedure. 4. Remove pum p belt. a. Check belt tightness and check for a bent pulley. (Pulley should not wobble with engine running.) 5. Remove pump from attaching parts and remove pump from vehicle. b. Check to make sure hoses are not touching any other parts of the vehicle, particularly sheet metal. Installation 1. Position pum p assembly on vehicle (Fig. 6) and install attaching parts loosely. 2. Connect and tighten hose fittings. c. Check oil level, filling to proper level if necessary, following operations 1 through 10. This step and Step "d" are extremely im portant as low oil level an d /o r air in the oil are the most frequent causes of objectionable pump noises. TR U C K SUP P - SER VIC E STEERING 9-5 P-SERIES MOTOR HOME STEERING CONNECTING ROD SUPPORT ,LEFT IDLER ARM PITMAN ARM IDLER ARM ASSEMBLY STEERING GEAR ASSEMBLY RELAY ROD STEERING GEAR MOUNTING BRACKET TIE ROD ASSEMBLY STEERING GEAR ASSEMBLY PITMAN ARM STEERING ARM G-SERIES F ig . 4 --S te e rin g L in k a g e d. Check the presence of air in the oil. A ir will show up as milky appearing oil. If air is present, attem pt to bleed system as described in operations 1 through 10. 11. The presence of trapped air in the system will cause the fluid level in the pump to rise when the engine is turned off. Continue to bleed system until this condition no longer occurs. TR U C K SUP P ■ S E R V IC E 9-6 STEERING NOTE: S lo t in a d ju s te r sleeve m u s t n o t w it h in th is area c la m p ja w s. NOTE: E q u a l th r e a d le n g th s m u s t be v is ib le a t in n e r a n d o u te r en d s o f a d ju s te r sleeve w h e n a sse m b le d t o s te e rin g k n u c k le . NOTE: L o c a te c la m p s w i t h i n to le ra n c e s h o w n . \ CAUTION: C la m p m u s t be b e tw e e n & c le a r o f d im p le s b e fo re to r q u in g n u t. H O R IZ O N T A L ' L IN E AD JU S TER S LEEVE REARW ARD R O T A T IO N “S L O T VIEW NOTE: E q u a l th r e a d le n g th s m u s t be v is ib le a t in n e r a n d o u te r e n ds o f a d ju s te r sleeve w h e n asse m b le d t o s te e rin g k n u c k le . SLO Ti H O R IZ O N T A L L IN E / NOTE: L o c a te c la m p s w i t h i n to le ra n c e s h o w n . ,A D J U S T E R SLEEVE / / CAUTION: C la m p m u s t be b e tw e e n & c le a r o f d im p le s b e fo re t o r q u in g n u t. REARW ARD R O T A T IO N NOTE: S lo t in a d ju s te r sleeve m u s t n o t be w it h in th is area o f c la m p ja w s. NOTE: E q u a l th r e a d le n g th s m u s t be v is ib le a t in n e r a n d o u te r en ds o f a d ju s te r sleeve w h e n a sse m b le d to s te e rin g k n u c k le . V E R T IC A L L IN E N SLO T AD JU S TER NOTE: S lo t in a d ju s te r sleeve m u s t n o t w it h in th is area c la m p ja w s. 'S L E E V E NOTE: L o c a te c la m p s , w it h in to le ra n c e sh o w n . CAUTION: C la m p m u s t be b e tw e e n & c le a r o f d im p le s b e fo re t o r q u in g n u t. REARW ARD R O T A T IO N VIEW Fig. 5--T ie Rod C lam p s TR U C K S U P P - SER VIC E STEERING 250 G 10 L-6 C 10 K10 Fig . 6 - P o w e r S te e r in g P u m p 292 305, 350, 400 C 10-30 K 10-20 P 20-30 9-7 V-8 WITH C-60 F ig . 9 --P o w e r S te e r in g P u m p L-6 G 20-30 C 10-30 K 20 P 20-30 Fig . 7 --P o w e r S te e r in g P u m p 350 V-8 MOTOR HOME F ig . 1 0 - P o w e r S te e r in g P u m p 454 V-8 C 10-30 F ig . 1 1 - P o w e r S te e r in g P u m p T R U C K S UPP - SER VIC E 9-8 STEERING R o ta te ho se a s s e m b ly a g a in s th y d r a b o o s t h o u s in g a sse m b ly b e fo re t ig h te n in g n u t. HA .6 4 IN C H M IN I M U M CLEARANCE R o ta te ho se asse m bly, a g a in st s te e rin g gear h o u s in g b e fo re tig h te n in g n u t. VIEW B 292 L-6 G 30 W/HYDRABOOST F ig . 1 5 ~ P o w e r S te e r in g H o se R o u tin g o r ie n ta t e p re s s u re hose w h e n in s ta llin g , ro ta te p ip e ends t o re s t a g a in s t p u m p s u p p o r t lo w e r. 250 or 292 L-6 G 10-30 S p e e d o c a b le a n d p a rk in g b ra k e c a b le t o be r o u te d a b o v e p o w e r s te e rin g p ip e s a n d m a in ta in cle a ra n c e . F ig . 1 3 --P o w e r S te e r in g H o s e R o u tin g T R U C K SUPP - S ER VICE STEERING 9-9 R o ta te ho se a s s e m b ly a g a in s t h y d r a b o o s t h o u s in g a s s e m b ly b e fo re tig h te n in g n u t. R o ta te ho se a s se m b ly a g a in s t s te e rin g gear h o u s in g b e fo re tig h te n in g n u t. VIEW B 350 or 400 V-8 G 30 W/HYDRABOOST -.6 4 M I N I M U M C LEARANCE F ig . 2 1 - P o w e r S te e r in g H o se R o u tin g T o o r ie n ta te p re s s u re ho se w h e n in s ta llin g , r o ta te p ip e en d s t o re s t a g a in s t s te e rin g p u m p h o u s in g . A S p e e d o c a b le a n d p a rk in g b ra k e c a b le t o be ro u te d above p o w e r s te e rin g p ip e s a n d m a in ta in c le a ra n ce . C la m p m u s t be in s ta lle d w it h b o lt h e ad to w a r d f r o n t o f v e h ic le . 305, 350, 400 V-8 G 10-30 F ig . 1 9 - P o w e r S te e r in g H o s e R o u tin g C lip m u s t be in s ta lle d p a ra lle l w i t h i n ± 3° o f brace. H ose m u s t be lo c a te d a g a in s t pum p a s s e m b ly B 6 IN C H E S VIEW A H ose a s s e m b ly m u s t be lo c a te d a g a in s t h y d ra b o o s t m o u n t in g ^ b ra c k e t. VIEW B 350 V-8 MOTOR HOME Fig. 2 3 - P o w e r S te e rin g Hose Routing TRUC K SUP P ■ S E R VIC E 9-10 STEERING VIEW A 454 V-8 C 10-30 EXCEPT HYDRABOOST R o u te P ip e A s s e m b ly - ln le t p a ra lle l t o o f s te e rin g gear. F ig . 2 4 - P o w e r S te e r in g H o s e R o u tin g 454 V-8 C 20-30 W/VACUUM POWER BRAKES AND 4.56 AXLE R o u te p ip e a s s e m b ly -in le t o u tb o a r d 1 5 °t o p a ra lle l o f s te e rin g gear. F ig . 2 7 - P o w e r S te e r in g H o s e R o u tin g 454 V-8 MOTOR HOME H ose a s s e m b ly m u s t be lo c a te d a g a in s t h y d r a b o o s t m o u n tin g b ra c k e t. F ig . 2 8 - P o w e r S te e r in g H o s e R o u tin g H ose a s s e m b ly m u s t be in s ta lle d a g a in s t s te e r in g y gear c o v e r. 1 R o u te p ip e a s s e m b ly 1 5 ° to p a ra lle l o f s te e rin g gear. 454 V-8 C 30 W/HYDRABOOST AND 4.56 AXLE Fig. 2 6 - P o w e r S te e ri n g Hose Routing T R U C K SUP P - SER VIC E STEERING 9-11 TRUC K S U P P - S E R VIC E 9-12 STEERING 1. PUMP PULLEY REMOVER J-25034 2. PUMP PULLEY INSTALLER J-25033 Fig. 3 1 ~ S p e c i a l To ols TR U C K SUP P • SER VIC E S E C T IO N 10 WHEELS AND TIRES The 1976 wheel and tire maintenance and service operations remain essentially the same as outlined in the 1974 Truck Service Manual. Tire Inflation Pressure Tables and additional inform ation for torquing dual wheels on P300 models have been revised as listed below to 1976 specifications. A T T A C H M E N T OF D U A L W H E E L S ON P 300 MODELS To assure secure attachm ent of the dual disc wheels, it is im portant that all dirt or rust scale be removed from the mating surface of the wheels, hub, and clamp ring as well as the stud and nut. PO W ER D R IV E NUTS T H E N M A N U A LLY IN SPEC T TO RQ U E AT 130-180 FT. LBS. M A N U A L TO R Q U E ONLY: 150-200 FT. LB. DUAL WHEEL SINGLE WHEEL Fig . 1 - W h e e l C o d e L o c a tio n T R U C K S U P P - S ER VIC E 10-2 WHEELS A N D TIR ES TIRE LOAD & INFLATION PRESSURE PA SSE N G E R TY PE T IR E S FOR LIGHT TRU CKS U SE I) IN HIGHWAY SE R V IC E Tire Size E78-15 F78-15 G78-15 G78-15 G R 78-15 H78-15 H78-15 J78-15 JR 78-15 L78-15 LR78-15 L78-15 L78-15 8.25-15 Range Load 20 970 1060 1140 1140 1140 1240 1240 1300 1300 1380 1380 1380 1380 1140 B B B D B B D B B B C C D D Tire Load Limits at Various Inflation Pressures 26 28 32 34 30 22 24 1030 1110 1190 1190 1190 1310 1310 1370 1370 1460 1460 1460 1460 1190 1080 1160 1260 1260 1260 1370 1370 1440 1440 1530 1530 1530 1530 1260 1130 1220 1310 1310 1310 1440 1440 1500 1500 1590 1590 1590 1590 1310 1180 1270 1370 1370 1370 1500 1500 1570 1570 1670 1670 1670 1670 1370 1230 1320 1420 1420 1420 1560 1560 1630 1630 1730 1730 1730 1730 1420 1270 1370 1470 1470 1470 1610 1610 1690 1690 1790 1790 1790 1790 1470 36 38 40 1530 1570 1620 1670 1670 1720 1770 1830 1860 1860 1860 1530 1910 1910 1910 1570 1970 1620 2030 1670 T IR E S FO R L IG H T TR U C K S U SED IN HIGHW AY S E R V IC E TIRES USED AS SINGLES Tire Size 6.50-16 7.00-15 7.00-15 7.00-16 7.50-16 7.50-16 7.50-16 8 *.17.5 8-19.5 Load Range C c D C C D' E D D Tire Load Limits at Various Inflation Pressures 30 40 35 45 50 60 55 TUBE TYPE TIRES MOUNTED ON 5° TAPERED 1500 1610 1610 1720 1610 1720 1830 1940 1680 1800 1930 2060 1930 2060 2190 2310 1930 2190 2060 2310 65 60 75 BEAD SEAT RIMS 1270 1350 1350 1430 1620 1620 1620 1390 1480 1480 1560 1770 1770 1770 2670 2780 1640 — TUBELESS TIRES MOUNTED ON 15° TAPERED BEAD SEAT DROP CENTER RIMS _ _ 1790 1940 2075 2205 2335 2455 2110 • 2270 2410 2540 2680 — — - 2800 2040 2440 2410 2560 _ WIDE BASE TUBELESS TIRES USED AS SINGLES Tire Size 10-15 Tire Size C78-15LT H78-15LT 8 .00-16.5 8 .00-16.5 8.00-16.5 8 .75-16.5 8 .75-16.5 8.75-16.5 9.50-16.5 9.50-16.5 10-16.5 10-16.5 Tire Load Limits at Various Inflation Pressures Load Range 20 22 24 26 28 30 B 1390 1470 1540 1620 1690 1760 30 35 40 45 1080 1440 1360 1360 1360 1570 1570 1570 1860 1860 1840 1840 1180 1580 1490 1490 1490 1720 1720 1720 2030 2030 2010 2010 1280 1710 1610 1610 1610 1850 1850 1850 2190 2190 2170 2170 1370 1830 1730 1730 1730 1990 1990 1990 2350 2350 2330 2330 Load Range C C c D E C D E D E C D 32 34 36 38 Tire Load Limits at Various Inflation Pressures 50 55 60 65 70 75 1840 1840 1945 1945 2045 2045 2145 2240 2330 2110 2110 2500 2500 2240 2240 2650 2650 2350 2350 2780 2780 2470 2570 2680 2920 3050 3170 2480 2620 2750 65 70 TIRES USED AS DUALS Tire Size Load Range 30 35 40 Tire Load Limits at Various Inflation Pressures 45 50 55 60 75 TUBE TYPE TIRES MOUNTED ON 5 ° TAPERED BEAD SEAT RIMS 6 .50-16 7.00-16 7.00-16 7.50-16 7.50-16 8-17.5 8-19.5 8-19.5 C C D C D 1120 1260 1260 1430 1430 D D E TUBELESS TIRES MOUNTED ON 15°TAPERED BEAD SEAT DROP CENTER RIMS 2155 1700 1820 1935 2050 1445 1575 — — 1850 1990 2110 2230 2350 2460 1850 1990 2110 2230 2350 2460 — — 1225 1365 1365 1565 1565 (Refer to Tire Load and Infla tion Pressure Notes) 1320 1475 1475 1690 1690 1420 1580 1580 1815 1815 1685 1780 1870 1930 2040 2140 2570 2680 (#) W ) 2780 lb s . a t 80 lb s. pre ss u re . T R U C K SUP P - SER VICE WHEELS A N D TIR ES 10-3 TIRE LOAD AND INFLATION PRESSURE TIRES FOR LIGHT TRUCKS USED IN HIGHWAY SERVICE (Cont’d) W ID E BASE TUBELESS TIRES USED AS DUALS Tire Size 8.00-16.5 8.00-16.5 8.75-16.5 8.75-16.5 8.75-16.5 Tire Load Limits at Various Inflation Pressures Load Range 30 35 40 45 C D C D E 1195 1195 1380 1380 1380 1310 1310 1515 1515 1515 1415 1415 1630 1630 1630 1520 1520 1750 1750 1750 50 55 60 1620 1710 1800 1855 1855 1970 1970 2070 2070 65 70 75 2175 2260 2360 Tire Load and Inflation Pressure Notes 1. The " c o ld " tire infla tio n p ressu re rating app lies to the tire p ressure w h e n the ve h icle has not been driven fo r th re e hours or m ore, or driven less than one mile. 2. It is norm al fo r tire pressu re s to incre a se 4-8 PSI, or m ore, w h e n the tire s becom e " h o t" fro m drivin g. Do not "b le e d ", or reduce tire in fla tio n p ressu re s a fte r d riving yo ur vehicle. Bleeding serves to reduce " c o ld ” in fla tio n p ressure and increase tire fle xin g w h ic h can re su lt in tire dam age and fa ilu re . 3. For su sta in e d driving over 75 mph w ith p asse n g er car type tire s or w h e n using p assenger car type sn o w tire s, cold infla tio n p ressu re s should be increased 4 PSI above the recom m ended cold infla tio n p ressu re s in the T ire /W h e e l Load and In fla tio n Pressure C hart fo r th e load being ca rrie d up to a m axim um of 32 PSI fo r load range B tire s, 36 PSI fo r load range C, and 40 PSI fo r load range D. S ustained speeds above 75 mph are n o t re com m ended w h e n the 4 PSI a d ju s t­ m ent exceeds the m axim um p ressu re s sta te d above. 4. For su stained driving over 65 mph w ith tru ck typ e tire s or w he n using tru ck typ e sn o w tire s , cold in fla tio n p ressu re s should be incre a se d 10 PSI above those specifie d in the T ire /W h e e l Load and Infla tio n P ressure ch arts fo r the load being carried. W h e re the 10 PSI p re s ­ sure incre a se is lim ite d by the m axim um w he&l ca pa city sh ow n in the W h e el Code and Limits Chart, speed m ust be lim ite d to 65 mph or th e tire load reduced to the tire load lim it ind ica te d in the T ire /W h e e l Load and In fla tio n Pressure Chart fo r 10 PSI less cold in fla tio n p re s ­ sure. For special ope ra tin g co nd itio ns such as ca rrying slide-in ca m ­ pers o r o th e r high ce n te r o f g ravity loads, cold infla tio n p ressu re s may be incre a se d up to 10 PSI above th o se show n in the ta b le w ith no increase in loads. The to ta l increase in cold infla tio n pressu re s sh all n o t exceed 10 PSI above th e prop e r p ressu re s fo r the load being ca rrie d and m ust not exceed the w h e e l infla tio n p ressure and load ca p a city sh ow n on the w h e e l code and lim its chart, sh ow n in th is section . 5. A lw a y s use a tire pressure gauge (a p ocke t typ e gauge is recom ­ m ended) w h e n checking in fla tio n pressu re s. Radial tire s m ay have th e app e a ran ce of being u n d e r-in fla te d w h e n at recom m ended cold in fla tio n pressures. PRO PERLY IN F L A T E D R A D I A L TIRE P R O P E R L Y I N F L A T E D B IA S O R B IA S - B E L T E D TIRE 6. Be sure to re in sta ll the tire in fla tio n va lve caps, if so equipped, to p re ve n t d irt and m oisture fro m ente rin g the valve core w h ic h could cause a ir leakage. WHEEL CODE AND LIMITS WHEEL LIMITS SIZE OF WHEEL CODE BT BJ BC BS DT FJ XH XL XU BR CY CF DK DJ XS BH FT AX AB YW CU CM 15 x 7 JJ 15 x8JJ 15 x 7 JJ 1 5 x 8 .0 0 JJ 15 x 6 JJ 1 6 .5 x 6 .0 1 5 x 6 JJ 16 x 5K 15 x 6 JJ 16 x 5K 19.5 x 5.25 16 x 5.50 F 16.5 x 6.0 16.5 x 6.75 16 x 6VzL 16.5 x 8.25 15 x 6JJ 1 5 x 6 JJ 19.5 x 6.75 16 x 6 K 19.5 x 5.25 17.5 x 5.25 MAX. MAX. LOAD (LBS) PRESS (PSI) 2040 1760 1910 70 40 70 40 55 85 55 55 55 55 75 70 70 85 85 70 70 70 85 75 85 1760 1670 2680 1670 1800 1670 1800 2460 2440 2350 3170 2780 2750 1910 2040 2780 2440 2800 2155 70 Load Range Replaces Ply Rating A B C D E 2 4 6 8 10 TRUC K SUP P - S E R VIC E S E C T IO N 11 CHASSIS SHEET METAL IN D E X General D escription.......................................................... 11-1 M aintenance and A djustm ents....................................... 11-1 Hood Lock Assembly-CK Series............................... 11-1 Carburetor A ir Inlet Snorkels-CK Series.................11-1 Rear Fender - C K Series.............................................11-1 Running Board - CK Series........................................ 11-1 Hood Rod Support - G Series....................................11-1 GENERAL DESCRIPTION The service procedures for all 1976 truck chassis sheet metal are essentially the same as those outlined in the 1974 Light D uty Truck Service Manual, Section 11, except as described below. MAINTENANCE AND ADJUSTMENTS To repair or replace either the hood lock assembly or the carburetor outside air inlet snorkels, the radiator grille must be removed prior to disassembly. Refer to Section 13, Radiator and Grille, of the 1976 Light D uty T ruck Service and Overhaul M anual for proper procedures. HOOD LOCK ASSEMBLY Service procedure for the 1976 C K Series hood lock is essentially the same as outlined in the 1974 Light Duty Truck Service M anual, Section 11, except for the slight modification to the lock assembly due to the new radiator grille, as shown in Fig. 1. CARBURETOR OUTSIDE AIR INLET SNORKELS (Fig. 2) Removal 1. Raise hood and remove carburetor air duct from air snorkel by sliding duct rearward. 2. Remove two (2) screws attaching air snorkel to radiator support and remove from vehicle. Installation Reverse removal procedure to install snorkel. REAR FENDER CK-SERIES Refer to Figs. 3 and 4 for removal and installation of rear fenders and fender braces for both C and K Series Trucks. RUNNING BOARDS CK-SERIES HOOD ROD SUPPORT - G-SERIES Refer to Fig. 6 for removal and installation of hood rod support. Refer to Fig. 5 for removal and installation of running boards and hangers. TR U C K S U P P - S ER VIC E 11-2 C H A S S IS SHEET M E T A L F ig . 5 --R u n n in g B o a rd , H a n g e r, a n d B ra c e -C K S e rie s TRUC K SUP P - SER VIC E S E C T IO N 12 ELECTRICAL-BODY AND CHASSIS NOTE: Except for the following changes, all information listed in Section 12 of the 1974 Light D uty Truck Service Manual is applicable to 1976 light duty trucks. Refer to 1974 Light Duty Truck Service M anual for any service procedure not contained herein. LIGHTING SYSTEM MAINTENANCE AND ADJUSTMENTS HEADLAMP ADJUSTM ENT HEADLAMP AIM IN G The headlamps must be properly aimed in order to provide maximum allowable road illumination. Headlamps should be checked for proper aim at new car predelivery, every 12 months, after installing a new sealed beam unit or if front end sheet metal is adjusted or repaired. Some state and local authorities have special or additional requirem ents for headlamp aiming and these requirements should be followed. H orizontal and vertical aiming of each sealed beam unit is provided by two adjusting screws which move the mounting ring in the body against the tension of the coil spring (fig. 1). Both circular and rectangular headlamps are aimed in the same manner. There is no adjustm ent for focus since the sealed beam unit is set for proper focus during m anufacturing assembly. Before headlam p aiming process begins, it is necessary to prepare vehicle as follows: 1. Remove any large am ounts of mud or ice from underside of fenders. 2. Place vehicle on a fairly level flat surface. It is not necessary that this surface be exactly level. 3. M ake sure tires are properly inflated. 4. Clean headlam p lenses. 5. Fuel tank should be one half full. If heavy load is normally carried in load area, it should remain there. 6. Driver should remain in vehicle or an equivalent weight placed in driver’s seat. 7. "Rock" vehicle sideways so as to equalize the springs. Also check springs for sag, broken leaves or coils. Using headlam p aiming device J-25300, aim headlamps as follows: 1. A ttach a floor slope adapter-J-25300-6 (fig. 2) to each of the headlamp aimers-J-25300-1, -2 (fig. 3). The adapters will easily snap into position on the aimer when properly positioned. 2. Place aimers with floor slope adapters attached at the center line of each wheel on one side of the vehicle (fig. 4). Aimers must be placed facing each other. Make sure dials of all three adjusting knobs are set at "0" (zero). 3. Level each aimer unit by turning knob of floor slope adapter (fig. 2) either clockwise or counterclockwise until the top level vial bubble of the headlamp aimer registers in the centered (level) position. 4. Look into the top sight opening of either the front or rear aiming unit and turn horizontal knob in both directions until the split image is aligned. 5. Transfer the plus or minus reading indicated on the horizontal dial to the floor slope offset dial (fig. 3). Then return horizontal dial to a zero setting. TRUC K SUPP - S ER VIC E 12-2 ELEC TR IC A L-BO DY A N D C H A S S IS aimer half-way between the two readings obtained. For instance: A D J U S T IN G K N O B + 5 and -5 Readings Equal 0 Average + 4 and -2 Readings Equal + 1 Average + 2 and -4 Readings Equal -1 Average Also, if one area is regularly used to aim headlamps the floor slope adjustm ent procedures can be eliminated by using tape or paint to indicate on the floor the center line for the rear wheel of all vehicles. Then check the floor level for several vehicles with varying wheelbase measurements. Indicate on the floor a front wheel center line for each wheelbase along with the plus or minus reading for that position. Thereafter, each time the headlamps are aimed, merely place the rear wheels of the vehicle on the rear wheel center line and transfer the plus or minus reading of the front wheel center line to the floor slope dial of the aiming unit. 7. Remove floor slope adapters from each unit and attach a headlamp adapter (fig. 5) as determined by type of headlamps on the vehicle. There is an adapter for all standard size and shape sealed beam units. LEVEL V IA L (U S E D O N L Y FO R C A L IB R A T IO N ) F ig . 2 - F lo o r S lo p e A d a p te r J - 2 5 3 0 0 - 6 8. Position aimer with headlamp adapter attached so that the three guide points of the lamp are in contact with the three steel inserts inside the headlamp adapter. Secure aimer to headlamp by pushing locking handle (fig. 3) forward to engage rubber suction cap and then immediately pull locking handle rearward until it locks in place. Headlamp aimers must always be used in pairs and installed so that they face each other (fig. 6). 6. Repeat steps 3 thru 5 for other unit. NOTE: Unless the floor is abnormally sloped, it is not necessary to obtain floor slope readings for both sides o f the vehicle. If for some reason floor is abnormally sloped, it may require that different readings be used for each side o f the vehicle. In this instance, determine the floor level for BOTH sides of the vehicle. It is then necessary to set the floor slope offset dial of EACH HORIZONTAL DIAL VERTICAL DIAL LO CKING HANDLE FLOOR SLOPE KNOB FLOOR SLOPE DIAI LEVEL VIAL VERTICAL KNOB HORIZONTAL KNOB SUCTION CUP SIGHT O PEN IN G V IEW ING PORT LEVEL VIAL M O C K IN G HANDLE AIMER J-25300-2 SHOW N AIMER J-25300-1 SIMILAR Fig. 3 - H e a d l a m p A im e r TRUC K SUPP - SER VICE ELE C TR IC A L-B O D Y A N D C H A S S IS 12-3 A IM E R J -2 5 3 0 0 -2 A IM E R J -2 5 3 0 0 -2 A IM E R J -2 5 3 0 0 -1 PORT ^ M l l 'iH I %I ‘1:W * S IG H T O P E N IN G TARGETS M U S T FACE EA CH O T H E R FLOOR SLOPE A D A PTER ( j -2 5 3 0 0 - 6 R IG H T SIDE S H O W N . LEFT SIDE J -2 5 3 0 0 -2 G O E S IN REAR A N D J -2 5 3 0 0 -1 IN FR O N T . R IG H T SIDE S H O W N A IM E R J -2 5 3 0 0 -1 Fig. 4 -F lo o r Slope Adjustm ent (Typical) 9. Check to make sure floor slope dials of the aimers obtained in step 5 has not been disturbed. Make sure horizontal dial is at zero. 10. Look into top sight opening of the aimer to see that the split image target lines are visible in the viewing port. If necessary, rotate each aim er slightly to locate target. 11. Turn horizontal adjusting screw of headlamp (fig. 1) until split image of target line appears in sight opening as one solid line. To remove "backlash" make final adjustment by turning horizontal adjusting screw in a clockwise direction. 16. Recheck target alignment on both aimers and readjust horizontal aim if necessary. 17. Remove aimers by holding aimer securely with one hand while pressing the vacuum release button located on locking handle of aim er with the other hand. If headlamp aiming equipment is not available, use procedure described in Section 12 of 1974 Service Manual. 7 " C IR C U LA R H E A D L A M P ADAPTER J -2 5 3 0 0 -4 R E C T A N G U LA R H E A D L A M P A DAPTER J - 2 5 3 0 0 -3 12. Repeat steps 9 thru 11 for other aimer. 13. M ake sure vertical dial is at zero. NOTE: A zero setting is generally required. Some state or local authorities have special requirements. Consult those authorities and use the special requirement as required. 14. T urn headlamp vertical screw (fig. 1) until the top level vial bubble registers in the centered (level) position. 15. Repeat steps headlamp. 13 and 5 " C IR C U LA R H E A D L A M P ADAPTER J -2 5 3 0 0 -5 14 for opposite aimer and Fig. 5 -H e a d la m p Adapters T R U C K S U P P - S E R VIC E 12 -4 ELEC TR IC A L-BO DY A N D C H A S S IS HEAD LAM P ADAPTER v LEVEL V IA L V IE W IN G PORT H EAD LA M P AIMER J-2 5 3 0 0 -1 HEAD LAM P AIMER J -2 5 3 0 0 -2 F ig . 6 - H e a d la m p A im in g (T y p ic a l) SERVICE OPERATIONS HEADLAMPS W ARNING BUZZER Replacement (Fig. 7). 1. Disconnect electrical connector from LPS (Lamps) socket o f fuse panel. 2. Disconnect electrical connector from IGN (Ignition) socket o f fuse panel. 3. Disconnect electrical connector to instrum ent panel harness. 4. Remove strap securing buzzer to instrum ent panel harness. 5. Install replacement headlamp warning buzzer in reverse sequence of removal. SEAT BELT W A RNING SYSTEM All 1976 C-K type light duty trucks have a non-sequential timer controlled seat belt warning system. This new system will have an instrum ent panel warning light that will illuminate every time the ignition switch is turned on, whether or not the driver’s seat belt is buckled, but will automatically go off after 4-8 seconds. The buzzer will also be controlled by the 4-8 second timer, but will operate only if the driver has not buckled-up prior to turning on the ignition. If no attem pt is made to buckle-up after turning on the ignition, the buzzer will also shut-off automatically after 4-8 seconds. A trouble shooting diagnostic chart and wiring schematic are shown in Figures 8 and 9. TRUC K SUP P ■ SER VIC E SEAT BELT REMINDER LIGHT/BUZZER DIAGNOSIS Fig. 8-Seat Belt Reminder System ELECTRICAL-BODY AND CHASSIS Diagnosis 12-5 12-6 ELEC TR IC A L-BO DY A N D C H A S S IS F ig . 9 - S e a t B e lt R e m in d e r S y s te m S c h e m a tic INSTRUMENTS AND GAGES AMMETER-VOLTMETER The am m eter for all light duty trucks has been cancelled for 1976 and is being replaced by a voltmeter. The difference between the two is mainly that an ammeter shows the actual charging rate of the battery whereby a voltmeter indicates the condition (voltage level) of the charging system and battery. Service (replacement) procedures are the same for voltmeter as for the ammeter. W IRING DIAG RAM S Truck wiring diagrams are shown in 1976 Light, Medium and Heavy D uty Truck W iring Diagram Manual. TRUC K SUP P - SER VICE S E C T IO N 14 BUMPERS Service procedures for the 1976 Light Duty Truck are basically carryover except for the G model truck bumper procedures listed below. FRONT BUMPER (Fig. 1) Removal 1. Remove nuts securing bumpers to brackets and braces from left and right side. Remove bumper. 2. Remove the license plate support nut and bolts. 3. If necessary to remove the braces and brackets, remove screws securing brackets and braces to sheet metal. NOTE: The bum per may be removed with the brackets and braces attached. 4. If equipped with bumper guards (Fig. 1) they may be removed from the face bar at this time. Installation Reverse removal steps to install bumpers. Refer to torque specifications for proper torque values. REAR STEP BUMPER (Fig. 2) Removal 1. Remove nuts securing bum per to brackets and braces and remove bumper. 2. Remove bracket and braces from vehicle. NOTE: The bum per may be removed with brackets and braces attached if necessary. Installation Install in reverse order of removal. Refer to torque specification for correct torque values. TRUC K S UPP - SER VIC E S E C T IO N 15 ACCESSORIES NOTE: Except for the following changes, all information listed in Section 15 of the 1974 Light D uty T ruck Service M anual is applicable to 1976 light duty trucks. Refer to 1974 Light Duty Truck Service M anual for any service procedure not contained herein. CRUISE MASTER IN D E X G eneral D escription...........................................................15-1 Theory of O peration......................................................... 15-1 Cruise M aster U n its........................................................ 15-2 M aintenance and A dju stm en ts....................................... 15-3 Regulator...................................... ......................................15-3 Servo U n it......................................................................... 15-3 Brake Release Sw itches..................................................15-4 E lectric.............................................................................. 15-4 V acuum ............................................................................ 15-4 Component Part Replacem ent........................................ 15-6 Regulator............................................................................. 15-6 Servo....................................................................................15-6 Column M ounted Engagement Switch........... ............ 15-6 Diagnosis...............................................................................15-6 Electrical System Troubleshooting.............................. 15-6 Engagement Switch T e st.............................................. 15-6 Harness T e s t....................................................................15-6 Servo and Vacuum System T e st.................................15-7 System Diagnosis C harts................................................ 15-9 GENERAL DESCRIPTION The Cruise M aster is a speed control system which employs engine manifold vacuum to power the throttle servo unit. The servo moves the throttle, when speed adjustment is necessary, by receiving a varying amount of controlled vacuum from the regulator unit. The speedometer cable (from the transmission) drives the regulator, and a cable (from the regulator) drives the instrum ent panel speedometer. The engagement of the regulator unit is controlled by an engagement switch located at the end of the turn signal lever. On "Dealer Installed Cruise Systems", the engage switch is m ounted on the lower part of the instrument panel to the left of the steering column. Two brake release switches are provided: an electric switch disengages the regulator unit and a vacuum valve decreases the vacuum in the servo unit to quickly return the throttle to idle position. The operation of each unit of the system and the operation of the entire system under various circumstances is described under "Theory of Operation" below. THEORY OF OPERATION The purpose of the Cruise M aster system is to allow the driver to maintain a constant highway speed without the necessity of continually applying foot pressure to the accelerator pedal. Speed changes are easily made and override features allow the vehicle to be stopped, slowed or accelerated as described below. Engaging th e Cruise System The driver accelerates to the speed at which he desires to cruise and partially depresses and releases the cruise control engagement switch button located at the end of the directional signal lever (on dealer installed systems, this switch will be on the instrum ent panel). The cruise system takes over speed control, and within engine limitation, TR U C K S U P P - SER VIC E 15-2 A C C ES S O R IE S maintains this speed regardless of changes in terrain. The Engagement Switch button performs these functions: 1. Above 30 mph, when partially depressed and released, it engages the cruise system. 2. W hen depressed fully and held there, it disengages the system. 3. W hen released slowly from the fully depressed position, it will engage the system at the existing speed and cruise at that speed (above 30 mph). NOTE: See Fig. 1C “ Engage Switch O peration” . The system re-engages at the higher speed when the button is slowly released. To Cruise At A Lower Speed -Disengage the system by depressing the engagement switch button fully and holding it there until the vehicle has decelerated to the new desired speed; then release the button slowly. The system re-engages at the lower speed when the button is slowly released. CRUISE MASTER UNITS Figures 3C and 4C show the units in the installed position on the vehicles. 1. The Engagement Switch, which is located at the end of the directional signal lever (or bottom on instrument panel), is used to control the system and for upward and downward speed adjustments. Speed Changes Override -The accelerator pedal may be depressed at any time to override the cruise system. Release of the accelerator pedal will return the vehicle to the previous cruise speed. To Cruise At A Higher Speed -Depress the accelerator pedal to reach the new desired speed. Then, fully depress and slowly release the cruise control engagement switch button. 2. The Regulator (fig. 2C) is m ounted in the speedometer cable line. It is a combination speed sensing device and control unit. W hen engaged, it senses vehicle speed and positions the Servo Unit to m aintain the selected speed. 3. The Servo Unit is m ounted on the left front inner fender and is connected by a cable to the throttle linkage. It opens or closes the throttle as dictated by the Regulator. THE C RU ISE CONTROL ENGAGE SWITCH A S S E M B L IE S , BOTH TURN S IG N A L & IN S TR U M E N T PANEL MOUNTED TYPES, INCORPORATE THREE POS IT IO N SWITCHES. THESE POSITIONS ARE: ( A) T H E “ R E L E A S E D ” O R N O R M A L P O S I T I O N (B) T H E “ E N G A G E ” P O S I T I O N (C) T H E “ T R I M - D O W N ” P O S I T I O N . P A R T IA L L Y DEPRESSING TH E ENGAGE SWITCH WILL A C T IV A T E THE SYSTEM A N D IT W ILL REMAIN ACTIVITED WHEN T H E S W I T C H IS R E LE A S E D . THE C R U IS E SYSTEM IS DEA C TIVATED WHEN THE BRAKES ARE A P P L I E D O R W H E N T H E E N G A G E S W I T C H IS DEPRESSED FULLY AND HELD IN T H E “ TR IM -D O W N ” POSITION. T H E “ TR I M -D O W N ” SW ITCH POSITION IS NORM ALLY USED TO DECREASE THE C R U I S I N G S P E E D . W H I L E T H E S W I T C H IS H E L D IN T H E “ T R I M - D O W N ” P OS IT IO N T H E CRUISE S Y S T E M IS “ O F F ” A N D T H E C A R S P E E D W I L L G R A D U A L L Y DECREASE. WHEN THE DESIRED C R U I S I N G S P E E D IS R E A C H E D , T H E S W I T C H IS SLOWLY RELEASED A N D TH E CRUISE SYSTEM W ILL RE-ENG AG E. IF THE SW ITCH IS R ELEA SED FROM THE “ TR IM -D O W N ” P O S I T I O N V E R Y R A P I D L Y , I T IS Q U I T E L I K E L Y T H A T THE SYSTEM W IL L N OT RE-ENGAGE. T H I S IS N O R M A L A N D IS A V O I D E D B Y A SLO WER, M O R E D E L I B E R A T E R EL EA SE OF THE SW ITCH FROM THE “ TRIM-DOWN” POSITION. NOTE: A SPEED-SWITCH B UILT INTO THE R E G U L A T O R A S S E M B L Y PR EVENTS EN G A G IN G THE CRUISE SYSTEM BELOW A P P R O X . 30 MPH. Fig. 1C~Cruise M aster Engagement Sw itches TRUC K SUPP - S ER VICE A C C ES S O R IE S EN GAGE T E R M IN A L H O LD T E R M IN A L O U T P U T TO SP E E D O M E T E R * TO TEE' F IT T IN G — 15-3 4. The Cruise Brake Release Switch, which is m ounted on the brake pedal bracket, disengages the system electrically when the brake pedal is depressed. 5. The Cruise Brake Release Valve, which is m ounted on the brake pedal bracket, disengages the system pneumatically when the brake pedal is depressed. 6. The Cable and Casing Assemblies drive the regulator and speedometer. IN PU T F R O M T R A N S M IS S IO N LO CKN U T - O R IF IC E TU BE & C O N N E C TO R ASSEM BLY F R O M E N G IN E VACUUM A IR FILTER & S O L E N O ID H O U S IN G C O V E R Fig. 2C--Regulator Unit MAINTENANCE AND ADJUSTMENTS The components of the Cruise-M aster System are designed to be replaced should they become inoperative. The Regulator is cali brated in such a m anner during m anufacturing that overhaul operations are impractical. However, one adjustm ent may be made to the Regulator to correct speed drop or increase at the time of engagement. REGULATOR {FIG. 3C) One regulator adjustm ent is possible - Engagement Cruising Speed Zeroing (to remove any difference between engagement and cruising speed). No regulator adjustment should be made, however, until the Servo Cable adjustment has been checked and vacuum hoses are checked for leaks, kinks, or other restrictions. If the vehicle cruises at a speed a few m ph above or below the engagement speed, this error can be corrected with a simple adjustment of the orifice tube in the regulator (see fig. 2C). CAUTION: Never remove orifice tube from casting. It cannot be reinstalled once it has been removed. 1. To check cruise speed error, engage Cruise-M aster at 60 mph. 2. If vehicle cruises below engagement speed, screw orifice tube outward . 3. If vehicle cruises above engagement speed, screw orifice tube inward . NOTE: Each 1/4 turn of the orifice tube will change cruise speed approximately one mph. Snug-up lock nut after each adjustment. If a Regulator is found to be defective and not simply out-of-adjustment, it must be replaced. D uring replacement, check the hoses which connect to the Regulator and replace any which are cracked or deteriorated. SERVO UNIT (FIG. 4C) Before adjusting the Servo Cable, make sure the carburetor is set at its lowest idle throttle position by manually setting the fast idle cam at its lowest step with the ignition switch T R U C K SUP P - S ER VIC E 15-4 A CC ESSO R IES "O FF". Adjust the cable so there is as little lost motion at the Servo as possible (see Fig. 4C). replacement. Vacuum If the Servo Unit is found to be defective, replacement is required. Note the condition of the hoses and replace any which are cracked or deteriorated. The vacuum valve plunger must clear the pedal arm when the arm is moved 5/16 inch, measured at the switch (fig. 6C). BRAKE RELEASE SW ITCHES (Fig. 4C) An inoperative (sticking, plugged, or leaking) vacuum valve must be replaced. Vacuum valve replacement is similar to brake lamp switch replacement. Be certain that the hose to the valve is connected firmly and is not cracked or deteriorated. Electric The Cruise M aster brake release switch electrical contacts must be switched open when the brake pedal is depressed .38" to .64", measured at the brake pedal. COLUMN MOUNTED ENGAGEMENT SW ITCH The engagement switch is serviced only by replacement of the turn signal lever assembly. An inoperative switch must be replaced. Switch replacement procedure is similar to standard brake lamp switch ~ n ^CRUISE CONTROL V AC U U M HOSE CABLE SERVO BOOT CONTROL CABLE ADJUSTMENT W ith C able installed to C able B racket and C a rb u re tor, install C able to Servo Bracket. Using second ball on Servo Chain, install S ervo Chain on C able. W ith th ro ttle c o m p le te ly closed ( ignition o ff and fa st idle Cam o ff) adjust C able Jam Nuts until Servo Chain is almost tig h t ( some slack).lTighten Jam Nuts to sp e cifie d torque, then re m o ve plastic re ta in e r ( not show n) ( used to retain b o o t in depressed position) and pull ru b b e r b o o t ( p a rt o f S ervo) o v e r w asher ( p a rt o f C able). ACCELERATOR CABLE SUPPORT SERVO CABLE ____ — A [ v ie w CARB LEVER Snap Fastener Tab o v e r end o f stud in d ire c tio n o f a rro w . - H SERVO CABLE LF4/LF8/LS9 Fig. 4C -- Serv o C o m p o s it e (C-K Tr ucks) T R U C K S U P P - SER VIC E A C C ESSO R IES 15-5 B R A K E P E D A L IN N O R M A L P O S ITIO N B R A K E P E D A L P O S ITIO N W HEN V A C U U M V A L V E OPENS .38 TO .64 IN S T A L L A T IO N OF S E L F -A D JU S T IN G V A C U U M R E LE A S E V A L V E 1. Install m o u n tin g c lip in to bracket. 2. Depress brake pedal & push valve in to clip u n til shoulder on valve asm b o tto m s o u t against clip. 3. A d ju s t valve by bringing pedal to norm al po sitio n so th a t valve is open when pedal is depressed to dim ension shown. Fig. 6 C - V a c u u m V a lv e TR U C K SUP P - SER VIC E 15-6 A C C ES S O R IE S COMPONENT PART REPLACEMENT 2. Disconnect cruise master engagement switch wiring REGULATOR harness plug on steering column. Replacement 3. Remove plastic protector from cruise master wiring 1. Disconnect battery ground cable. harness on column. 2. Disconnect speedometer cables at regulator. 3. Disconnect vacuum and wiring harness at regulator body. 4. Remove regulator to bracket screws and remove regulator. 4. Remove turn signal lever (see Section 9 of this Manual). 5. Connect a 15" piece of piano wire to cruise master wiring harness plug for installation before easing turn signal lever assembly up and out of the column. 5. To install, reverse Steps 1-4 above. SERVO Installation Replacement 1. A ttach new engagement switch harness plug to piano 1. Disconnect battery ground cable. wire routed through column. 2. Disconnect vacuum line at servo can. 3. Remove servo cover. Disconnect ball chain from cable retainer. 2. Pull connector and wire gently down column to prevent 4. Remove servo to bracket screw(s) and remove servo. 3. Install turn signal lever (see Section 9 of this Manual). 5. To install, reverse Steps 1-4 above. 6. Adjust the servo cable as outlined in Figure 4C. COLUMN MOUNTED ENGAGEMENT SW ITCH scraping wire insulation. 4. Slide plastic wiring protector over harness and up column. 5. Connect cruise master wiring harness on column. Removal 6. Connect battery ground cable. 1. Disconnect the battery ground cable. DIAGNOSIS ELECTRICAL SYSTEM TROUBLESHOOTING 1. Check fuse and connector. 2. Check electric brake switch as follows: a. Unplug connector at switch. b. Connect ohm m eter across cruise master contacts on brake switch. The ohm m eter must indicate no continuity when the pedal is depressed and continuity when pedal is released. The cruise release brake switch (electric) is adjusted as is the standard stop light brake switch. c. Replace electric brake switch if needed. 3. Check clutch release switch (manual transmission only) same as electric release switch above. at electrical wiring harness connector then perform the following tests (fig. 7C). T e s t# 1-C onnect ohmmeter between term inal # 1 (brown wire) and terminal # 2 (blue wire). Continuity shall be m aintained until switch is depressed all the way in. T e st# 2 -C o n n e ct ohm m eter between te rm in a l# 1 (brown wire) and term inal# 3 (black wire). No continuity shall be shown; however, when the button is partially depressed, continuity shall be indicated. W hen the button is pressed all the way down, no continuity shall be shown. T e st# 3 -C o n n e ct ohmmeter between term inal# 2 (blue wire) and term inal# 3 (black wire). Button released, no continuity; however, when the button is depressed partially and fully, continuity shall be shown. Harness T est (see Fig. 7C) Engagem ent S w itc h Test Check engagement switch and connecting wiring as follows: Unplug engagement switch connector (brown, blue, black) 1. Disconnect engage switch wire harness connector from the main harness connector (red, brow n/w hite, and white wires). A C C ES S O R IE S 2. Connect ohm m eter between point C (brow n/w hite stripe wire in main wire harness) and ground. M ake sure the Regulator is well grounded to the chassis. The ohmmeter should read between 42 and 49 ohms. If a resistance either above or below the value indicated is shown, then disconnect the connector from the Regulator and measure the resistance of the brow n/w hite stripe wire from point C to D. It should measure 40 ohms + 2 ohms. 3. If a resistance either above or below the value indicated is shown, the main wiring harness should be replaced. NOTE: W hen disconnecting or reconnecting the main wiring harness connector from the Regulator, care should be exercised so as not to damage the blade connectors or the wiring harness. The disconnect may be facilitated by prying carefully on the plastic connector with a small screwdriver. 4. M easuring the solenoid coil circuit resistance between point E (H old Terminal) and ground, the ideal resistance should be between 5 and 6 ohms. A reading of less than 4 ohms indicates shorting in the coil circuit. A reading of more than 7 ohms indicates excessive 15-7 resistance in the coil circuit. Either extremity indicates replacement of the Regulator assembly. The main harness wiring from point F to G (white wire) should also be checked for continuity. Servo and V acuum S ystem Test To determine the condition of the diaphragm, remove hose from the Servo Unit and apply 14 inches of vacuum to the tube opening and hold in for one minute. The vacuum shall not leak down more than 5 inches of vacuum in one minute. If leakage is detected, replace the Servo. To utilize engine as a vacuum source, proceed as follows: 1. Disconnect Servo cable at carburetor and vacuum hose from the Servo, then connect engine vacuum directly to the Servo fitting. 2. Note position of Servo diaphragm. 3. Start engine--the diaphragm should pull in. 4. Clamp off engine vacuum supply line and check for leakage. The cruise release brake valve (vacuum) and connecting hoses can likewise be checked using a vacuum pump. 15-8 ACCESSORIES Fig. 7C--Electro-Pneumatic Schematic A C C ES S O R IE S 15-9 CRUISE MASTER TROUBLESHOOTING CHECK I FOR SYSTEMS W ITH E R R A TIC CRUISE PERFORMANCE CHECK II FOR IN O P E R A T IV E SYSTEMS M A K E A L L TESTS W ITH TRAN SM ISSIO N SELECTOR IN “ P A R K ” & P A R K IN G BRAKE ON EXCEPT WHERE IN D IC A T E D OTHERW ISE. RECONNECT A N Y DISCONNECTED HOSES A N D /O R E L E C T R IC A L CONNECTORS IN PROPER M A N N E R A T THE COM PLETION OF TEST. FIG. 8 FIG. 9 CHECK I 1. CHECK SERVO C ABLE A D JU S TM EN T - MUST H A V E M IN IM U M A M O U N T OF LOST M O TIO N (SEE SERVICE A D JU S TM EN T PROCEDURE, FIG. 4) 2. CHECK FOR PINCHED, K IN K E D , PLUGGED, OR D AM AG ED V A C U U M HOSES. ALSO CHECK V AC U U M FITTIN G S . 3. CHECK SPEEDOMETER C ABLE R O U TING . IT MUST NOT BE K IN K E D OR H A V E TOO SHARP A T U R N IN G R AD IU S (NOT LESS T H A N 6” R AD IU S). CHECK D R IV E C ABLE FOR D ISTO RTED OR BENT TIPS. FERRULES MUST BE SNUG. 4. CHECK FOR A B IN D IN G T H R O T T LE LIN K A G E C O N D ITIO N . 5. CHECK A D JU S TM EN T OF BRAKE RELEASE SWITCH & V A C U U M RELEASE V A L V E . (SEE SERVICE & ADJUSTM ENTS) 6. CHECK FOR PROPER O PERATIN G PROCEDURE OF THE ENGAGE SWITCH (SEE FIG . 1) 7. IF STEPS 1 THROUGH 6 DO NOT SOLVE THE PROBLEM PROCEED W ITH CHECK II . SPECIAL NOTE P E R T A IN IN G TO E NG AG EM ENT-C RU ISIN G SPEED ZER O IN G . IF THE CAR CRUISES BELOW E N G AG E M E N T SPEED, SCREW THE O R IF IC E TUBE O U TW AR D . IF THE CAR CRUISES ABO VE THE E NG AG EM ENT SPEED, SCREW THE O R IFIC E TUBE IN W ARD . EACH 1/4 TURN W IL L C HANG E THE CAR SPEED A P P R O X IM A T E LY ONE MPH. ENG AG EM ENT ACC UR ACY TESTIN G TO BE DONE A T 60 MPH. SNUG UP LOCK N U T A FTE R EACH ADJU STM EN T. C A U T IO N : DO NOT REMOVE O R IFIC E TUBE FROM C ASTIN G . Fig. 8C -- S y ste m D ia g no sis C h a rt No. 1 TRUC K SUP P - SER VIC E 1 5 -1 0 A C C ES S O R IE S CHECK n Fig. 9C -- S y ste m D iag no sis C h a rt N o . 2 T R U C K SUP P • S ER VICE S E C T IO N IN D E X SECTION 1976 10-30 SERIES TRUCK CHASSIS SERVICE and OVERHAUL MANUAL SUPPLEMENT NAME 1 AIR CO N DITIO NING COMPRESSOR 3 FRONT AXLE 4 REAR AXLE DIFFERENTIAL CARRIER 5 BRAKES 6 ENGINE O V E R H A U L S E C T IO N T h e o v erh au l section o f this m anual inclu d es new o r re ­ vised p ro c e d u re s in volved in d isassem b ly and assem b ly o f m ajo r co m p o n e n ts. 6M CARBURETORS 6Y STARTING MOTOR SOLENOID AN D DELCOTRON 7M CLUTCH AND M A N U A L TR A N S M IS S IO N 7A A U TO M A TIC TR A N S M IS S IO N 9 MANUAL STEERING GEAR, POWER STEERING P U M P AND GEAR SPECIFICATIONS — AT REAR OF M A N U A L Printed In U.S.A. SECTION 1 AIR CONDITIONING C O N T E N T S OF T H IS S E C T IO N Axial Six-Cylinder Com pressor........................................................ .. 1-1 Radial Four-Cylinder C om pressor.................................................... 1-26 Special T o o ls........................................................................................... 1-38 AXIAL SIX-CYLINDER COMPRESSOR IN D E X M inor Repair Procedures................................................. 1-1 Clutch Plate and Hub A ssem bly..................................1-3 Pulley and Bearing Assem bly....................................... 1-4 Clutch Coil and Housing A ssem bly............................ 1-7 M ajor Repair Procedures................................................ 1-8 For Compressor REM OVAL A N D IN STA LLA TIO N , see 1974 Service M anual (page 1A-58). For all practical purposes, all V8 engine equipped vehicles make use of the same air conditioning 6 cylinder compressor. Shaft Seal........................................................................... 1-8 Pressure Relief Valve....................................................... 1-11 Internal M echanism ........................................................ 1-11 Leak Testing - External and In tern al......................... 1-24 Actual differences between compressors are found in their mounting brackets, pulleys, connector assemblies and compressor capacities, none of which will affect the following Overhaul Procedures. MINOR REPAIR PROCEDURES The following operations to the Compressor Clutch Plate and Hub, Pulley and Bearing, and Coil Housing are covered as "Minor" because they may be performed W ITH O U T FIRST PURGING THE SYSTEM OR REMOVING THE COMPRESSOR from the vehicle. The Compressor Shaft Seal assembly and Pressure Relief Valve may also be serviced W ITHO UT REMOVING THE COMPRESSOR from the vehicle but these operations are covered later in this section as "Major Repair Procedures" because the system MUST FIRST BE PURGED of Refrigerant. Illustrations used in describing these operations show the compressor removed from the vehicle only to more clearly illustrate the various operations. When servicing the compressor, remove only the necessary components that preliminary diagnosis indicates are in need of service. Refer to Fig. 1 and Fig. 2 for information relative to parts nomenclature and location. Removal and installation of external compressor components and disassembly and assembly of internal components must be performed on a clean workbench. The work area, tools, and parts must be kept clean at all times. Parts Tray J-9402 (see Fig. 33) should be used for all parts being removed, as well as for replacement parts. Although certain service operations can be performed without completely removing the compressor from the car, the operations described herein are based on bench over-haul with the compressor removed from the car. They have been prepared in sequence in order of accessibility of the components. Pad fender/skirt and secure compressor near top of fender skirt with wire, rope, etc. TRUC K SUP P - O V E R H A U L 1-2 AIR Front Head \ CONDITIONING O -R ing Shaft Seal Assembly Seal Seat Switch Retainer Ring Seal Seat Retainer Ring O -R in g s A bsorbent Sleeve Seal Retainer Clutch Coil Retainer Ring COMPRESSOR Compressor Shell Clutch Coil and Housing Assembly Pulley Bearing Fig. 1--Exploded Superheat Switch Bearing Retainer Pulley Retainer Ring Switch O-Ring Clutch Plate and Hub Assembly lo c k Nut Rear Head O uter O il Pump G e a r j Retainer Ring Lock Nut View Rear Discharge V alve Plate Assembly Rear Suction Reed of A-6 Bushing Needle Bearing Compressor O - Ring Rear Cylinder H alf T eflo n Piston R in g - Bolt Shoe Disc ' T e flo n Ring T ype Piston T e flo n Piston Ring Shaft Discharge Crossover Tube Thrust Races Front Suction Reed Front Discharge V alve Plate Assembly A IR C O N D IT IO N IN G COMPRESSOR 1-3 SUCTION REED SHAFT SEAL ASM. TEFLON PISTON RING SHELL BALL SHAFT \ PISTON FRONT DISCHARGE V A L V E PLATE PULLEY A X IA L PLATE PULLEY BEARING SHOE DISC CLUTCH PLATE AND HUB ASSEMBLY REAR H E A D n -SEAL SEAT O IL PUMP GEARS RETAINER RING SUPERHEAT > SWITCH -SEAL SLEEVE / FRONT / ABSORBENT HEAD / SLEEVE / PRESSURE RELIEF VALVE O IL PICK-UP TUBE O IL SUMP THRUST RACE THRUST BEARING REAR C YLINDER HALF \ '--LI AN CH COIL HOUSING / FRONT C YLINDER SPACER HALF RETAINER RING (C O N VEX . SIDE FACING SPACER) SHAFT NUT F ig . 2 --A -6 C o m p re s s o r C ro s s S e c tio n CAUTION: Do not kink or place excessive tension on lines or hoses. W hen a compressor is removed from the car for servicing, the am ount of oil remaining in the compressor should be drained and measured. This oil should then be discarded and new 525 viscosity refrigerant oil added to the compressor. CLUTCH PLATE AND HUB ASSEMBLY Remove 1. Place Holding Fixture J-9396 in a vise and clamp the compressor in the Holding Fixture. 2. Keep clutch hub from turning with Clutch Hub Holder J-25030 or J-9403, and remove locknut from end of shaft using Thin Wall Socket J-9399 (Fig. 3). CAUTION: To avoid internal damage to the compressor, DO NOT DRIVE OR POUND on the Clutch Plate and Hub assembly OR on the end of the shaft. I f proper tools to remove and replace clutch parts are not used, it is possible to disturb the position o f the axial plate (keyed to the main shaft), resulting in compressor damage and seal leakage due to shifting o f the crankshaft. 3. Thread C lutch Plate and H ub assembly Remover J-9401 into hub. Hold body of Remover with a wrench and tighten center screw to remove Clutch Plate and Hub assembly (Fig. 4). F ig . 3 --R e m o v in g S h a ft L o c k N u t 4. Remove square drive key from shaft or drive plate hub. 5. Remove hub spacer retainer ring using Snap-Ring Pliers J-5403(#21), and then remove hub spacer (Fig. 5). 6. Inspect driven plate for cracks or stresses in the drive surface. D o not replace driven plate for a scoring condition. (Fig. 6). TR U C K SUP P - O V E R H A U L 1-4 A IR C O N D ITIO N IN G COMPRESSOR 2. Line up the key in the hub with keyway in the shaft (Fig- 7). 3. Position the Drive Plate Installer J-9480-1 on the threaded end of the shaft. The Spacer J-9480-2 should be in place under the hex nut on the tool. This tool has a left hand thread on the body. (Fig. 8). 4. Press the driven plate onto the shaft until there is approximately 3/32" space between the frictional faces of the clutch drive plate and pulley. CAUTION: Make certain key remains in place when pressing hub on shaft. A ZERO thrust race is approximately 3/32" thick and may be used to roughly gage this operation. Use Clutch Hub H older J-25030 or J-9403 to hold clutch plate and hub if necessary. 5. Install the hub spacer and, using Snap-Ring Pliers J-5403 (# 2 1 ), install the retainer ring (see installed Retainer Ring in inset of Fig. 2), with convex side of ring facing spacer. 6. Use Thin-W all Socket J-9399 and Clutch Hub Holder J-25030 or J-9403 to install a new shaft locknut w ith F ig . 4 - R e m o v in g C lu tc h P la te a n d H u b A s s e m b ly shoulder or circular projection on the locknut facing towards retainer ring. Tighten the nut to 14-26 lb. ft. torque. A ir gap between the frictional faces should now be .022" to .057"(Fig. 9). If not, check for mispositioned key or shaft. 7. The pulley should now rotate freely. 8. Operate the refrigeration system under M AXimum load conditions and engine speed at 2000 RPM . Rapidly cycle the clutch by turning the air conditioning on-and-off at least 15 times at approximately one second intervals to burnish the mating parts of the clutch. PULLEY AND BEARING ASSEMBLY Remove 1. Remove clutch plate and hub assembly as described in “Compressor Clutch Plate and Hub Asm .” Removal procedure. 2. Remove pulley retainer ring using Snap-Ring Pliers J-6435 (# 2 6 ), Fig. 10. F ig . 5 --R e m o v in g o r In s t a llin g R e ta in e r R in g in A -6 C lu tc h D riv e P la te If the frictional surface shows signs of damage due to excessive heat, the clutch plate and hub and pulley and bearing should be replaced. Check further for the underlying cause of the damage (i.e. low coil voltage coil should draw 3.2 amps at 12 volts) or binding of the compressor internal mechanism, clutch air gap too wide, broken drive plate to hub asm. springs, etc. Replace 1. Insert the square drive key into the hub of driven plate; allow it to project approximately 3/16" out of the keyway. 3. Pry out absorbent sleeve retainer, and remove absorbent sleeve from compressor neck. 4. Place Puller Pilot J-9395 over end of compressor shaft. CAUTION: I t is im portant tha t P u ller P ilo t J-9395 be used to prevent in tern a l damage to compressor when rem oving pulley. Under no circumstances should Puller be used DIRECTLY against drilled end of shaft . 5. Remove Pulley and Bearing Assembly using Pulley Puller J-8433 (Fig. 11). Inspection Check the appearance of the pulley and bearing assembly. See Fig. 6. The frictional surfaces of the pulley and bearing assembly should be cleaned with a suitable solvent before reinstallation. T R U C K SUPP - O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-5 D R IV E P L A T E D R IV E N P L A T E SC O R IN G O F D R IV E AND D R IV E N P L A T E S IS N O R M A L . DO N O T R E P L A C E F O R T H IS C O N D IT IO N . F ig . 6 --C lu tc h D riv e n P la te a n d D riv e P la te DRIVE PLATE INSTALLER J-9480-01 SPACER J-9480-2 KEY K E Y W A Y IN SHAFT J-9396 HOLDING FIXTURE HOLDING FIXTURE J-9396 F ig . 8 —In s t a llin g D riv e P la te F ig . 7 - - A lig n in g D riv e P la te K e y and prevent damage to bearing. Replace 1. If original pulley and bearing assembly is to be reinstalled, wipe frictional surface of pulley clean. If frictional surface of pulley shows any indication of damage due to overheating, the pulley and bearing should be replaced. 2. Check bearing for brinelling, excessive looseness, noise, and lubricant leakage. If any of these conditions exist, bearing should be replaced.See “ Compressor Pulley Bearing” Replacement Procedure. 3. Press or tap pulley and bearing assembly on neck of compressor until it seats, using Pulley and Bearing Installer J-9481 with Universal H andle J-8092 (Fig. 12). The Installer will apply force to inner race of bearing 4. Check pulley for binding or roughness. Pulley should rotate freely. 5. Install retainer ring, using Snap Ring Pliers J-6435 (# 2 6 ). 6. Install absorbent sleeve in compressor neck. 7. Install absorbent sleeve retainer in neck of compressor. Using sleeve from Seal Seat Remover-Installer J-23128, install retainer so that outer edge is recessed 1/32" from compressor neck face. 8. Install clutch plate and hub assembly as described in “ Compressor Clutch Plate and H ub Asm .’’Replacement Procedure. TRUCK SUPP - OVERH AUL 1-6 A IR C O N D ITIO N IN G COMPRESSOR PULLER J—843 3 CLEARANCE .022 " TO .057 PULLER PILOT PULLEY A N D B E A R IN G ASSEMBLY F ig . 9 --C h e c k in g A ir G a p F ig . 1 1 - R e m o v in g P u lle y a n d B e a r in g A s s e m b ly SNAP RING PLIERS J—6 4 3 5 (# 2 6 ) PULLEY ASSEMBLY UN IVERSAL HANDLE J-8 0 9 2 RETAINER RING PULLEY A N D BEARING INSTALLER J —9481 F ig . 1 0 --R e m o v in g P u lle y R e ta in e r R ing Fig. 1 2 —In s ta llin g P u lle y a n d B e a r in g A s s e m b ly PULLEY BEARING Remove BEARING RETAINER 1. Remove clutch plate and hub assembly as described in “Compressor Clutch Plate and H ub A sm .” Removal procedure. 2. Remove pulley and bearing assembly as described in “Compressor Pulley and Bearing A sm .” Removal procedure. 3. Remove pulley bearing retainer ring with a small screwdriver or pointed tool (Fig. 13). 4. Place pulley and bearing assembly on inverted Support Block J-21352 and, using Pulley Bearing Remover J-9398 with Universal Handle J-8092, drive Bearing assembly out of pulley (Fig. 14). Replace 1. Install new bearing in pulley using Pulley and Bearing Installer J-9481 with Universal Handle J-8092 (Fig. 15). The Installer will apply the force to the outer race of the bearing. Fig. 1 3 --R e m o v in g P u lle y a n d B e a r in g R e ta in e r R ing CAUTION: D O N O T C L E A N N E W B E A R IN G A SS E M B LY W IT H A N Y TYPE O F S O LV E N T Bearing is supplied with correct lubricant when assembled and requires no other lu brican t a t any time. TR U C K S UPP ■ O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-7 2. Install bearing retainer ring, making certain that it is properly seated in ring groove. “Compressor Pulley and Bearing A sm .” Replacement procedure. 3. Install pulley and bearing assembly as described in 4. Install clutch plate and hub assembly as described in “Compressor Clutch Plate and Hub Asm .” Replacement procedure. UNIVERSAL HANDLE J-8092 CLUTCH COIL AND HOUSING ASSEMBLY PULLEY & BEARING INSTALLER J-9398 PULLEY Remove 1. Remove clutch plate and hub assembly as described in “Compressor Clutch Plate and Hub Asm.” Removal procedure. ASSEMBLY 2. Remove pulley and bearing assembly as described in “Compressor Pulley and Bearing Asm.” Removal procedure. 3. Note position of terminals on coil housing and scribe location on compressor front head casting . 4. Remove coil housing retaining ring using Snap-Ring Pliers J-6435 ( # 2 6 ) (Fig. 16). 5. Lift Coil and Housing assembly off compressor. Replace 1. Position coil and housing assembly on compressor front head casting so that electrical terminals line up with marks previously scribed on compressor (Fig. 17). F ig . 1 4 --R e m o v in g B e a r in g fr o m P u lle y A s s e m b ly 2. Align locating extrusions on coil housing with holes in front head casting. 3. Install coil housing retainer ring w ith flat side of ring facing coil , using Snap-Ring Pliers J-6435 (# 2 6 ). 4. Install pulley and bearing assembly as described in “Compressor Pulley and Bearing A sm .” Replacement procedure. 5. Install clutch plate and hub assembly as described in “Compressor Clutch Plate and H ub Asm .” Replacement Procedure. THIS RIDGE OF TOOL MUST BE UP WHEN INSTALLING BEARING Clutch Coil and Housing Assembly R etainer Ring SUPPORT BLOCK J— 21 PULLEY A N D BEARING INSTALLER J—9481 F ig . 1 5 - -In s ta llin g B e a r in g o n P u lle y F ig . 1 6 -R e m o v in g C o il H o u s in g R e ta in e r R ing TRUC K S U P P • O V E R H A U L 1-8 A IR C O N D ITIO N IN G COMPRESSOR ELECTRICAL TERMINALS Fig. 1 7 —1n s ta llin g C o il H o u s in g MAJOR A-6 COMPRESSOR REPAIR PROCEDURES Service repair procedures to the Compressor Shaft Seal, Pressure Relief Valve and Superheat Switch, or disassembly of the Internal Compressor Mechanism are considered "M A JO R " SINCE THE REFRIGERATION SYSTEM M UST BE COMPLETELY PURGED OF REFRIGERANT before proceeding and/or because major internal operating and sealing components of the compressor are being disassembled and serviced. A clean workbench, preferably covered w ith a sheet of clean paper, orderliness in the work area and a place for all parts being removed and replaced is of great importance, as is the use of the proper, clean service tools. Any attem pt to use make-shift or inadequate equipment may result in damage and/or improper compressor operation. These procedures are based on the use of the proper service tools and the condition tha t an adequate stock of service parts is available. All parts required for servicing are protected by a preservation process and packaged in a manner which w ill eliminate the necessity of cleaning, washing or flushing of the parts. The parts can be used in the mechanism assembly just as they are removed from the service package. Piston shoe discs and shaft thrust races will be identified by “num ber” on the parts themselves for reference to determine their size and dimension (see Fig. 41). SHAFT SEAL Seal Leak Detection A SHAFT SEAL SHOULD NOT BE CHANGED BECAUSE OF AN OIL-LINE ON THE HOOD INSULATOR. The seal is designed to seep some oil for lubrication purposes. Only change a shaft seal when a leak is detected by the following procedure . When refrigerant system components other than the compressor are replaced, the compressor must be removed and oil drained from the compressor if oil was sprayed in large amounts due to leaks or a broken shaft seal. Compressor shaft seals, unless replaced during a compressor overhaul, are to be replaced only on the basis of actual refrigerant leakage as determined by test with an electronic-type leak detector. TRUC K S U P P - O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-9 F ig . 1 9 --R e m o v in g S h a ft S e a l S e a t a n d O -R ing 5. W ith Seal Protector J-22974 still over the end of the shaft, engage the tabs on the seal assembly with the tangs on Seal Installer J-9392 by twisting the tool clockwise, w hile pressing the tool down . Then lift the seal assembly out (see Fig. 20). 6. Remove the seal seat O-ring from the compressor neck using O-Ring Remover J-9533 (See Fig. 19). F ig . 1 8 --R e m o v in g o r In s ta llin g S h a ft S e a l S e a t R e ta in in g R ing W H E N R E PL A C IN G T H E SH A FT SEAL ASSEMBLY, even if the compressor remains on the vehicle during the operation, IT W ILL BE N ECESSARY TO P U R G E TH E SYSTEM O F R E F R IG E R A N T as outlined earlier in the Service Manual. Remove 1. A fter first purging the system of refrigerant, remove the clutch plate and hub assembly and shaft key as described in “Compressor Clutch Plate and H ub A sm .” Removal procedure. 7. Recheck the shaft and inside of the compressor neck for dirt or foreign m aterial and be sure these areas are perfectly clean before installing new parts. Inspection SEALS SHOULD NOT BE REUSED. ALW AYS USE A NEW SEAL KIT ON REBUILD. Be extremely careful that the face of the seal to be installed is not scratched or damaged in any w a y . M ake sure that the seal seat and seal are free of lint and dirt that could damage the seal surface or prevent sealing. Replace 2. Pry out the sleeve retainer and remove the absorbent sleeve. Remove the shaft seal seat retaining ring, using Snap-Ring Pliers J-5403 (# 2 1 ). See Fig. 18. 1. Coat new seal seat O-ring with clean 525 viscosity refrigerant oil and install in compressor neck, making certain it is installed in bottom groove (Fig. 20 and Fig. 21). Top groove is for retainer ring. Use O-Ring Installer J-21508. 3. Thoroughly clean inside of compressor neck area surrounding the shaft, the exposed portion of the seal seat and the shaft itself. This is absolutely necessary 2. Coat the O-ring and seal face of the new seal assembly with clean 525 viscosity refrigerant oil. Carefully m ount the seal assembly to Seal Installer J-9392 by engaging the tabs of the seal with the tangs of the tool (Fig. 20). to prevent any dirt or foreign material from getting into compressor . 4. Place Seal Protector J-22974 over the end of the shaft to prevent chipping the ceramic seat. Fully engage the knurled tangs of Seal Seat Rem over-Installer J-23128 into the recessed portion of the seal seat by turning the handle clockwise . Lift the seat from the compressor with a rotary motion (Fig. 19). CAUTION: DO NOT tighten the handle with a wrench or pliers; however, the handle must be hand-tightened securely to remove the seat. 3. Place Seal Protector J-22974 (Fig. 20) over end of shaft and carefully slide the new seal assembly onto the shaft. Gently tw ist the tool CLOCK-WISE, while pushing the seal assembly down the shaft until the seal assembly engages the flats on the shaft and is seated in place. Disengage the tool by pressing downward and twisting tool counterclockwise. 4. Coat the seal face of the new seal seat with clean 525 viscosity refrigerant oil. M ount the seal seat on Seal Seat Remover-Installer J-23128 and install it in the compressor neck, taking care not to dislodge the seal TR U C K S UPP - O V E R H A U L 1-10 A IR C O N D ITIO N IN G COMPRESSOR O-RING -INSTALLER J-21508 L E A K T E S T superheat ADAPTER SHUTOFF J-9 625 SWITCH OIL FITTING SEAL INSTALLER J -9 3 9 2 ^ SEAL PROTECTOR J-22974 F ig . 2 2 --L e a k T e s tin g A -6 C o m p re s s o r position and oil sump down, rotate the compressor shaft in normal direction of rotation several times by hand. Leak test the seal with an electronic-type Leak Detector. Correct any leak found. Remove and discard the shaft nut. F ig . 2 0 --R e p la c in g S e a l a n d O -R ing 1 /3 2 " (APPROX.) ^ ------- -----------STR A IG H T EDGE l/VIRE GAGE ,026 SHOULD "GO" .075 SHOULD "NOT GO' A B S O R B E N T SLEEVE SLEEVE RETAINER SEAL SEAT RETAINER R IN G SEAL SEAT O R IN G SEAL ASSEMBLY F ig . 2 1 --C o m p re s s o r S h a ft a n d S e a l seat O-ring and being sure the seal seat makes a good seal with the O-ring. Remove Seal Protector J-22974 from the end of the shaft (see Fig. 19). 5. Install the new seal seat retainer ring w ith its flat side against the seal s e a t , using Snap-Ring Pliers J-5403 (# 2 1 ). See Fig. 18. Use the sleeve from Seal Seat Rem over-Installer J-23128 (Fig. 19) to press in on the seal seat retainer ring so that it snaps into its groove. 6. Install Compressor Leak Test Fixture J-9625 on rear head of compressor and connect gage charging lines as shown for bench test in Fig. 22 or pressurize SUCTION SID E of compressor on car with Refrigerant-12 vapor to equalize pressure to the drum pressure. Temporarily install the shaft nut and, with compressor in horizontal 7. Remove any excess oil, resulting from installing the new seal parts, from the shaft and inside the compressor neck. 8. Install the new absorbent sleeve by rolling the material into a cylinder, overlapping the ends, and then slipping the sleeve into the compressor neck with the overlap towards the top of the compressor. With a small screwdriver or similar instrum ent, carefully spread the sleeve until the ends of the sleeve butt at the top vertical centerline. 9. Position the new metal sleeve retainer so that its flange face will be against the front end of the sleeve. Pulley Puller Pilot J-9395 (See Fig. 11) may be used to install the retainer. Press and tap with a mallet, setting the retainer and sleeve into place (retainer should be recessed approximately 1/32" from the face of the compressor neck). See Fig. 21. 10. Reinstall the clutch plate and hub assembly as described in“Compressor Clutch Plate and Hub Asm .” Replacement procedure. Some compressor shaft seal leaks may be the result of mispositioning of the axial plate on the compressor shaft. The mispositioning of the axial plate may be caused by im proper procedures used during pulley and driven plate removal, pounding, collisions or dropping the compressor. If the axial plate is mispositioned, the carbon face of the shaft seal assembly may not contact the seal seat and the rear thrust races and bearing may be damaged. If there appears to be too m uch or insufficient air gap between the drive and driven plates, dislocation of the shaft should be suspected. If the carbon seal is not seating against the seal seat, it will not be possible to completely evacuate the system as outlined under “Evacuating the Refrigeration System.” To check for proper positioning of the axial plate on the shaft, remove the clutch driven plate and measure the distance between the front head extension and the flat TRUC K SUP P ■ O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-11 DISCHARGE SYSTEM BEFORE REMOVING HIGH PRESSURE RELIEF VALVE OR SUPERHEAT SWITCH HI. PRESS RELIEF VALVE SUPERHEAT SWITCH REAR HEAD F ig . 2 3 —H i. P ress. R e lie f V a lv e L o c a tio n shoulder on the shaft as shown in Fig. 21. To measure this distance, use a wire gage (the clearance should be between .026" and .075"). If the shaft has been pushed back in the axial plate (measurement greater than .075"), disassemble the compressor and replace the shaft and axial plate assembly rear thrust races and thrust bearing. 11. Evacuate and charge system as outlined under "Evacuating and Charging the Refrigeration System". PRESSURE RELIEF VALVE W hen necessary to replace the pressure relief valve, located in the compressor rear head casting, the valve assembly should be removed after P U R G IN G T H E SYSTEM OF R E F R IG E R A N T and a new valve and gasket installed. The entire system should then be “Evacuated and Recharged.” (Fig. 23). INTERNAL M ECHANISM Service operations to the rear head or internal mechanism of the compressor should be performed w ith the compressor removed from the vehicle to insure that the necessary degree of cleanliness may be maintained. Clean hands, clean tools and a clean bench, preferably covered with clean paper, are of extreme importance. An inspection should be made of the internal mechanism assembly to determ ine if any service operations should be performed. A detailed inspection of parts should be made to determine if it is economically feasible to replace them. Remove 1. Before proceeding with disassembly, wipe exterior surface of compressor clean. 2. All oil in compressor should be drained and measured. Assist draining by positioning compressor with oil drain plug down. Record the amount of oil drained from the compressor. F ig . 2 4 - C o m p r e s s o r In s ta lle d in H o ld in g F ix tu re 3. Invert compressor and Holding Fixture J-9396 with front end of compressor shaft facing downward. (Fig. 24). Additional oil may leak from compressor at this time. All oil must be drained into a container^so that TO TA L am ount can be measured. A liquid measuring cup may be used for this purpose. D rained oil should then be discarded. 4. Remove four locknuts from threaded studs on compressor shell and remove rear head. Tap uniformly around rear head if head is binding. (Fig. 24) 5. Wipe excess oil from all sealing surfaces on rear head casting webs, and examine sealing surfaces (Fig. 25). If any damage is observed, the head should be replaced. 6. Remove suction screen and examine for any damage or contamination. Clean or replace if necessary. 7. Paint an identifying m ark on exposed face of inner and outer oil pump gears and then remove gears. Identifying marks are to assure that gears, if reused, will be installed on identical position. 8. Remove and discard rear head to shell O-ring. 9. Carefully remove rear discharge valve plate assembly. Use two small screwdrivers under reed retainers to pry up on assembly (Fig. 26). Do not position screwdrivers between reeds and reed seats . 10. Examine valve reeds and seats. Replace entire assembly if any reeds or seats are damaged. 11. Using two small screwdrivers, carefully remove rear suction reed (Fig. 27). Do not pry up on horseshoe-shaped reed valves . T R U C K SUPP - O V E R H A U L 1-12 A IR C O N D ITIO N IN G COMPRESSOR SUPERHEAT SHUTOFF SWITCH A LIN G SURFACES U C T IO N SCREEN EAR HEAD HELL TO HEAD O ' R IN G OIL PUMP R O TO R S F ig . 2 8 - R e m o v in g O il P ic k -U p T u b e F ig . 2 5 - R e a r H e a d R e m o v a l REAR DISCHARGE REED RETAINERS other hand. Invert compressor and position on bench with Internal Assembly Support Block resting on bench. 15. Lift front head and com pressor shell assembly up, leaving internal mechanism resting on Internal Assembly Support Block. CAUTION: To prevent damage to shaft, DO NOT TAP ON END OF COMPRESSOR SHAFT to remove internal mechanism. I f mechanism will not slide out o f compressor shell, tap on front head with a plastic hammer. 16. Rest compressor shell on its side and push front head assembly through compressor shell, being careful not to damage sealing areas on inner side of front head. Discard O-ring. Fig. 2 6 - R e m o v in g R e a r D is c h a rg e V a lv e P la te It may be necessary to tap on outside of front head, using a plastic hammer, to overcome friction of O-ring seal between front head and compressor shell. 17. Wipe excess oil from sealing surfaces on front head casting webs and examine sealing surface. If any surface damage is observed, the head should be replaced. # Rear Suction R F ig . 2 7 - R e m o v in g R e a r S u c tio n R eed 18. Remove front discharge valve plate assembly and front suction reed plate. Examine reeds and seats. Replace necessary parts. 19. Remove suction cross-over cover by prying with screwdriver between cylinder casting and cover (Fig. 29). 20. Examine internal mechanism for any obvious damage. If internal mechanism has sustained major damage, due to loss of refrigerant or oil, it may be necessary to use the Service internal mechanism Assembly rather than replace individual parts. 12. Examine reeds for damage, and replace if necessary. INTERNAL M ECHA NISM 13. Using Oil Pick-Up Tube Remover J-5139 (Fig. 28), remove oil pick-up tube. Remove O-ring from oil inlet. Disassembly 14. Loosen compressor from Holding Fixture J-9396, place Internal Assembly Support Block J-21352 over oil pump end of shaft and, holding Support Block in position with one hand, lift compressor from Holding Fixture with Use Parts Tray J-9402 (Fig. 33) to retain compressor parts during disassembly. 1. Remove internal mechanism from compressor as described in “Compressor Internal M echanism” Removal procedure. TR U C K S U P P - O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-13 F ig . 3 1 - S e p a r a tin g C y lin d e r H a lv e s TEFLON RING GROOVE (PISTON FRONT END) Fig . 3 2 - N o t c h I d e n tify in g F r o n t E nd o f A -6 P is to n 4. Carefully remove the rear half of the cylinder from the pistons and set the front cylinder half, with the piston, shaft and axial plate in Compressing Fixture J-9397. F ig . 3 0 - N u m b e r in g P is to n a n d C y lin d e r B o re s 2. Identify by pencil m ark, or some other suitable means, each piston numbering them as 1, 2, and 3 (Fig. 30). N um ber the piston bores in the front cylinder half in like manner, so that pistons can be replaced in their original locations. 3. Separate cylinder halves, using a wood block and mallet (Fig. 31). Make certain that discharge cross-over tube does not contact axial plate when separating cylinder halves (a new Service discharge cross-over tube will be installed later). CAUTION: UNDER NO 5. Pull up on compressor shaft and remove piston previously identified as No. 1, with balls and shoe discs, from axial plate. a. Inspect the Teflon piston rings for nicks, cuts or metal particles imbedded in exposed ring surface and replace the piston rings as required if either condition exists. See “Teflon Piston Ring” Replacement procedure. 6. Remove and discard the piston shoe discs. 7. Remove and examine piston balls, and if satisfactory for re-use, place balls in No. 1 com partm ent of Parts Tray J-9402 (Fig. 33). 8. Place piston in No. 1 com partm ent of Parts Tray J-9402, with notch in casting web at front end of piston (Fig. 32) into the dimpled groove of Parts Tray compartment. CIRCUM STANCES SH O U LD S H A F T B E STR U C K A T E IT H E R E N D in an effo rt to separate upper and low er cylinder 9. Repeat Steps 5 through 9 for Pistons No. 2 and No. 3. 10. Remove rear combination of thrust races and thrust halves because the shaft and the axial plate could be damaged. bearing from shaft. Discard races and bearing. TR U C K S UPP - O V E R H A U L 1-14 A IR C O N D ITIO N IN G COMPRESSOR Fig. 3 3 --A -6 P a rts T ra y F ig . 3 5 —In s ta llin g N e e d le B e a rin g Thrust Races SUPPORT BLOCK J-21352 Fig. 3 4 --R e m o v in g F ro n t T h r u s t R aces a n d B e a rin g s 16. Needle bearings may be removed if necessary by driving them out with special Thin-W all Socket J-9399. Insert socket in hub end (inner side) of cylinder head and drive bearing out. To install needle bearing, place cylinder half on Support Block J-21352, and insert bearing in end of cylinder head with bearing identification marks UP. Use Needle Bearing Installer J-9432 and drive bearing into cylinder head (Fig. 35), until tool bottoms on the cylinder face. Two different width needle bearings are used in Production compressors - a 1/2" size and a 5/8" size. The bearings ARE interchangeable. Service replacement bearings are all 1/2". 11. Remove shaft assembly from front cylinder half. If the discharge cross-over tube remained in the front cylinder half, it may be necessary to bend discharge cross-over tube slightly in order to remove shaft. 17. Wash all parts to be re-used with trichlorethylene, Stoddard solvent, kerosene, or a similar solvent. Air-dry parts using a source of clean, dry air. 12. Remove front combination of thrust races and bearing from shaft. Discard races and bearing. Compressor internal components may be identified by referring to Fig. 1 and Fig. 2. 13. Examine surface of axial plate and shaft. Replace as an assembly , if necessary. INTERNAL M E CHA NISM Gaging Operation A certain am ount of shoe disc wear on axial plate is normal, as well as some markings indicating load of needle bearings on shaft. 1. Install Compressing Fixture J-9397 on Holding Fixture J-9396 in vise. Place front cylinder half in Compressing Fixture, flat side down. Front cylinder half has long slot extending out from shaft hole. 14. Remove discharge cross-over tube from cylinder half, using self-clamping pliers. 2. Secure from Service parts stock four ZERO thrust races and three ZERO shoe discs. This is necessary only on original factory equipment, as ends of the tube are swedged into cylinder halves. The discharge cross-over tube in internal mechanism assemblies that have been previously serviced have an O-ring and bushing at EA CH E N D of the tube, and can be easily removed by hand (see Fig. 53). 15. Examine piston bores and needle bearings in front and rear cylinder halves. Replace front and rear cylinders if any cylinder bore is deeply scored or damaged. 3. Install a ZERO thrust race, thrust bearing, and a second ZERO thrust race on front end of compressor shaft. Lubricate races and bearing with petrolatum. 4. Insert threaded end of shaft through needle bearing in front cylinder half, and allow thrust race and bearing assembly to rest on hub of cylinder. 5. Now install a ZERO thrust race on rear end of compressor shaft (Fig. 36), so that it rests on hub of axial plate. Then install thrust bearing and a second ZERO thrust race. Lubricate races and bearing with petrolatum. TRUC K SUP P - O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-15 PISTON DRIVE FR O N T TH R UST RACES A N D B E A R IN G REAR NEEDLE THRUST BEARING AND "ZERO” THRUST RACES FRONT CYLINDER F ig . 3 6 - - ln s ta llin g R e a r T h r u s t R a c e s a n d B e a rin g s jm TEFLON RING1 Fig. 3 8 —In s t a llin g P is to n D u rin g G a g in g O p e ra tio n 10. Position piston over No. 1 cylinder bore (notched end of piston being on bottom and piston straddling axial plate) and lower the shaft to allow piston to drop into its bore (Fig. 38). 11. Repeat Steps 6 through 10 for Pistons No. 2 and No. 3. 12. Install rear cylinder half on pistons, aligning cylinder with discharge cross-over tube hole in front cylinder. Tap into place using a plastic mallet or piece of clean wood and ham m er (Fig. 39). F ig . 3 7 - - ln s ta llin g F R O N T S h o e D is c 13. Position discharge cross-over tube opening between a pair of Compressing Fixture bolts to permit access for feeler gage. 14. Install top plate on Compressing Fixture J-9397. Tighten nuts to 15 lb. ft. torque using a 0-25 lb. ft. torque wrench. 6. Lubricate ball pockets of the No. 1 Piston with 525 viscosity refrigerant oil and place a ball in each socket. Use balls previously removed if they are to be re-used. 7. Lubricate cavity of a ZERO shoe disc with 525 viscosity refrigerant oil and place shoe disc over ball in front end of piston (Fig. 37). Front end of piston has an identifying notch in casting web (Fig. 32). CAUTION: Exercise care in handling the Piston and R ing Assembly, p a rticu la rly during assembly in to and rem oval from the cylinder bores to prevent damage to the Teflon piston rings. Shoe discs should not be installed on rear of piston during following "Gaging" operation. Gaging Procedure (Steps 15 thru 18) The gaging operations which follow have been worked out on a simple basis to establish and provide necessary running tolerances. Two gaging procedures are necessary. The first is made to choose the proper size shoe discs to provide, at each piston, a .0016" to .0024" total preload between the seats and the axial plate at the tightest place through the 360-degree rotation of the axial plate at the tightest plate. The bronze shoe discs are provided in .0005" variations, including a basic ZERO shoe. The second , performed at the rear shaft thrust bearing and 8. R otate shaft and axial plate until high point of axial plate is over the No. 1 Piston cylinder bore. race pack, is designed to obtain .0025" to .0030" preload between the hub surfaces of the axial plate and the front and rear hubs of the cylinder. A total of 14 steel thrust races, including a basic ZER O race, are provided in increments of .0005" thickness to provide the required fit. 9. Lift shaft assembly up and hold front thrust race and bearing assembly against axial plate hub. Feeler Gage Set J-9564 or J-9661-01 may be used for gaging proper shoe disc size. Feeler Gage Set J-9564-01 or Dial Indicator Set J-8001-3 may be used to determine proper TRUC K SUP P • O V E R H A U L 1-16 A IR C O N D ITIO N IN G COMPRESSOR Fig. 4 0 --G a g in g R ear P iston Ball Fig. 3 9 --A s s e m b lin g C y lin d e r H alves thrust race size. PR O PE R SELEC TIO N O F TH R U ST RACES A N D BALL SEATS IS O F E X TR EM E IM PO R TA N C E. 15. Measure clearance between rear ball of No. 1 Piston and axial plate, in following manner: a. Select a suitable combination of well-oiled Feeler Gage leaves to fit snugly between ball and axial plate. which corresponds to the last three digits of the piece part number. (See Shoe Disc size Chart in Fig. 41 above.) Once a proper selection of the shoe has been made, THE M ATCHED C O M B IN A TIO N OF SHOE DISC TO REAR BALL AND SPHERICAL CAVITY IN PISTON M UST BE KEPT IN PROPER RELATIONSHIP during disassembly after gaging operation, and during final assembly of internal mechanism. b. A ttach a spring scale, reading in 1-ounce increments, to the feeler gage. A distributor point checking scale or Spring Scale J-544 may be used. 19. Repeat in detail the same gaging procedure outlined in Steps 15 through 18 for Piston No. 2 and No. 3. c. Pull on Spring Scale to slide Feeler Gage stock out from between ball and axial plate, and note reading on Spring Scale as Feeler Gage is removed (Fig. 40). 20. M ount Dial Indicator J-8001-3 on edge of Compressing Fixture J-9397 with Clamp J-8001-1 and Sleeve J-8001-2 (Fig. 43). Position Dial Indicator on rear end of shaft and adjust to “zero” . Reading should be between 4 and 8 ounces. d. If reading in Step c. above is under 4 O R over 8 ounces, reduce or increase thickness of Feeler Gage leaves and repeat Steps a. through c. above until a reading of 4 to 8 ounces is obtained. Record clearance between ball and axial plate that results in th* 4 to 8-ounce pull on Spring Scale. Apply full hand-force at end of mainshaft a few times before reading clearance. This will help squeeze the oil out from /betw een mating parts. Push upward and record measurement. Dial Indicator increments are .001"; therefore, reading must be estimated to nearest .0005". 16. Now rotate shaft 120° and repeat Step 15 between same ball and axial plate. Record this measurement. An alternate method of selecting a proper race is to use Gage Set J-9661-01, selecting a suitable feeler gage leaf until the result is a 4 to 8 ounce pull on the scale between the rear thrust bearing and upper (or outer rear) thrust race (Fig. 44). If the pull is just less than 4 ounces, add .0005" to the thickness of the feeler stock used to measure the clearance. If the pull on the scale reads just over 8 ounces, then subtract .0005" from the thickness of the feeler stock. Select a race TW O (2) FULL SIZES LARGER than feeler gage thickness (If feeler gage is .007", select a No. 9 or 090 race). If shaft is hard to rotate, install shaft nut onto shaft and turn shaft with wrench. 17. Rotate shaft another 120° and again repeat Step 15 between these same parts and record measurements. 18. Select a “num bered” shoe disc corresponding to minimum feeler gage reading recorded in the three checks above. (See example in Fig. 42). Place shoe discs in Parts Tray J-9402 com partm ent corresponding to Piston No. 1 and rear ball pocket position. 21. Select a thrust race w ith a "number" corresponding Shoe discs are provided in .0005" (one-half thousandths) variations, There are a total of 11 sizes available for field servicing. All shoe discs are m arked with the shoe size, to TW O (2) FULL SIZES LARGER than Dial Indicator or feeler gage measurement of the amount of end play shown. (If measurement is .007", select a No. 9 TR U C K SUPP - O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-17 SHOE DISC THRUST BEARING RACE PART NO. ENDING IN IDENTIFICATION STAMP MIN.FEELER GAGE READING PART NO. ENDING IN IDENTIFICATION STAMP DIAL INDICATOR READING 000 175 180 185 190 195 200 205 210 215 220 0 17-1/2 18 18-1/2 19 19-1/2 20 20-1/2 21 21-1/2 22 .0000 .0175 .0180 .0185 .0190 .0195 .0200 .0205 .0210 .0215 .0220 000 050 055 060 065 070 075 080 085 090 095 100 105 110 115 120 0 5 5-1/2 6 6-1/2 7 7-1/2 8 8-1/2 9 9-1/2 10 10-1/2 11 11-1/2 12 .0000 .0050 .0055 .0060 .0065 .0070 .0075 .0080 .0085 .0090 .0095 .0100 .0105 .0110 .0115 .0120 Fig. 4 1 -A v a ila b le A -6 S ervice S hoes and T h ru s t R aces P O S ITIO N 1 P O S IT IO N 2 P O S IT IO N 3 SELECT A N D USE SHOE N O . P IS TO N N O . 1 .0 1 9 " .0 1 9 5 " .0 1 9 " 19 P IS TO N N O . 2 .0 2 0 " .0 2 0 " .0 2 0 " 20 P IS TO N NO . 3 .0 2 1 " .0 2 1 " .0 2 2 " 21 Fig. 4 2 --S e le c tio n o f P ro p er A -6 S h o e Disc C lam p J-8001-1 Sleeve J-8001-2 Dial Indicator J-8001-3 Rear Rear Thrust Races Thrust Bearing field service. T hrust races are identified on the part by their thickness in thousandths, in excess of the thickness of the ZER O thrust race. This “num ber” also corresponds to the last three digits o f the piece part number. See Thrust Race size Chart in Fig. 41. 22. Remove nuts from top plate of Compressing Fixture J-9397, and remove top plate. Fig. 4 3 --G a g in g R ear T h ru s t R ace or 090 race). Place thrust race in right-hand slot at bottom center of Parts Tray J-9402 . Fifteen (15) thrust races are provided in increments of .0005" (one-half thousandths) thickness and one ZERO gage thickness, providing a total of 16 sizes available for 23. Separate cylinder halves while unit is in Fixture. It may be necessary to use a wood block and mallet. 24. Remove rear cylinder half and carefully remove one piston at a time from axial plate and front cylinder half. DO NOT LOSE THE RELATIONSHIP of the front ball and shoe disc and rear ball. Transfer each piston, ball, and shoe disc to its proper place in Parts TR U C K S U P P • O V E R H A U L 1-18 A IR C O N D ITIO N IN G COMPRESSOR Tray J-9402. 25. Remove rear outer ZERO thrust race from shaft and install thrust race just selected. The ZERO thrust race may be put aside for re-use in additional gaging or rebuilding operations. A-6 Teflon Piston Ring Replacement The Teflon piston ring installing, sizing and gaging tools are shown in Fig. 45. 1. Remove the old piston rings by C A R EFU LLY slicing through the ring with a knife or sharp instrument, holding the blade almost flat with the piston surface. Be careful not to damage the alum inum piston O R piston groove in cutting to remove the ring. 3. Set the piston on end on a clean, flat surface and install the Ring Installer Guide J-24608-2 on the end of the piston (Fig. 46). J-2460 8-3 O -R IN G 5. Push the Ring Installer J-24608-5 down over the Installer G uide J-24608-2 to install the Teflon ring in the piston ring groove (Fig. 47). If the Teflon ring is slightly off position in the ring groove, it can be positioned into place by fingernail or blunt-edged tool that will not damage the piston. The Ring Installer J-24608-5 will retain the Installer Guide J-24608-2 internally when the Teflon ring is installed on the piston. Remove the Installer Guide from the Ring Installer and DO NOT STORE THE INSTALLER GUIDE IN THE RING INSTALLER, as during storage. This could result in the O-Ring 2. Clean the piston and piston ring grooves with a recommended cleaning solvent and blow the piston dry with dry air (Trichlorethylene, Stoddard solvent, kerosene, or equivalent). J -2460 8-2 RING dull-side down and glossy-side up. the Ring Installer Segment Retainer O-Ring J-24608-3 w ill be stretched and possibly weakened W ARNING: Exercise personal care in cutting the piston ring for removal. J -2460 8-5 RING INSTALLER 4. Install a Teflon ring on the Ring Installer Guide J-24605-2 as shown in Fig. 46, w ith the dished or J-24608-3 not holding the Ring Installer segments tight enough to the Installer Guide J-24608-2 to properly install the Teflon ring on the piston. 6. Lubricate the piston ring area with 525 viscosity refrigerant oil and rotate the Piston and Ring Assembly into the Ring Sizer J-24608-6 at a slight angle (Fig. 49). R otate the piston, while pushing inward, until the piston is inserted against the center stop of the Ring Sizer J-23608-6. J -2460 8-6 R ING S IZ IN G TOOL J-24608-1 PISTON R ING GAGE INSTALLER GUIDE Fig. 4 5 - T e f l o n A -6 Piston Ring Instal ling, Sizing an d G a g in g To ols TRUC K SUP P • O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-19 J -2460 8-5 RING INSTALLER TEFLON RING Fig. 4 6 --T e flo n Piston Ring P o s itio n e d on Ring In s ta lle r G u id e CAUTION: D O N O T push the Piston and R ing Assembly in to the R ing Sizer J-24608-6 w ithout proper positioning and rotating as described above, as the ends o f the needle bearings o f the R ing Sizer may damage the end o f the piston. Fig. 4 7--I nsta 11i ng T e flo n Piston Ring 7. R otate the Piston and Ring Assembly in the Ring Sizer J-24608-6 several C O M PLETE turns, until the Assembly rotates relatively free in the Ring Sizer (Fig. 49). 8. Remove the Piston and Ring Assembly, wipe the end of the piston and ring area with a clean cloth and then push the Piston and Ring Assembly into the Ring Gage J-24608-1 (Fig. 50). The piston should go through the Ring Gage with a 6-lb. force or less without lubrication. If not, repeat Steps 6 and 7. 9. Repeat the procedure for the opposite end of the piston. Fig. 4 8 --T e flo n A -6 Piston Ring In s ta lle d in Piston G roove CAUTION: Reasonable care should be exercised in installing the piston in to the cylinder bore to prevent damage to the Teflon ring. A-6 COMPRESSOR INTERNAL M ECHA NISM CAUTION: D O N O T lay the piston down on a d irty Assembly surface where d irt o r m etal chips m ight become imbedded in the Teflon rin g surface. After properly performing the “ Gaging Procedure” , choosing the correct shoe discs and thrust races, and installing any needed Teflon Piston Rings, the cylinder assembly may now be reassembled. Be sure to install all NEW seals and O-rings. All are included in the compressor 10. Lubricate BOTH ENDS of the piston with 525 viscosity refrigerant oil before inserting the piston into the cylinder bore. TR U C K SUP P - O V E R H A U L 1-20 A IR C O N D IT IO N IN G COMPRESSOR P ISTO N A N D R IN G ASSEMBLY if**' .... ‘ | - - /V fl J -2 4 6 0 8 -6 R IN G S IZ IN G TO O L Fig. 4 9 ~ T u rn in g Piston and Ring Asm . into Ring S izin g T o ol Fig. 5 0 --G a g in g Piston Ring Size O-Ring Service Kit. Assembly procedure is as follows: 4. Repeat this operation for Pistons No. 2 and No. 3 (Fig. 52). 1. Support the F R O N T half of the cylinder assembly on Compressing Fixture J-9397. Install the shaft and axial plate, threaded end down , with its front bearing race pack (ZERO race, bearing N U M B E R E D race), if this was not already done at the end of the “Gaging Procedure” . 5. W ithout installing any O-rings or bushings, assemble one end of the new Service discharge cross-over tube into the hole in the front cylinder half (Fig. 53 and 54). 2. Apply a light smear of petroleum jelly to the “num bered” shoe discs chosen in the gaging procedure and install all balls and shoe discs in their proper place in the piston assembly. 6. Now rotate the shaft to position the pistons in a stair-step arrangement; then carefully place the rear cylinder half over the shaft and start the pistons into the cylinder bores (Fig. 55). 3. Rotate the axial plate so that the high point is above cylinder bore No. 1. Carefully assemble Piston No. 1, complete with ball and ZER O shoe disc on the front A N D ball and N U M B E R E D shoe disc on the rear , over the axial plate. Hold front thrust bearing pack tightly against axial plate hub while lifting hub. Insert the Piston Assembly into the front cylinder half (Fig. 51). 7. W hen all three Piston and Ring assemblies are in their respective cylinders, align the end of the discharge cross-over tube with the hole in the rear half of the cylinder. Be sure the flattened portion of this tube faces the inside of the compressor to allow for axial plate clearance (Fig. 54). 8. W hen all parts are in proper alignment, tap with a clean wood block and mallet to seat the rear half of the cylinder over the locating dowel pins. If necessary, clamp the cylinder in Compressing Fixture J-9397, to TRUC K SUP P - O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-21 "S E L E C T E D " R E AR SHOE DISC "S E L E C T E D " REAR TH R U S T RACE \ " Z E R O " TH R U S T RACES. LI FT S H A F T UPWARD A N D H O LD TH E TH R U S T RACES A N D B E A R IN G "Z E R O "F R O N T SHOE DISC ’■ D ischarge C rosso ver Tube TH R U S T B E A R IN G Fig. 5 1 —In s ta llin g 1st A -6 Piston A s s e m b ly In to Fro n t C y iin d e r H a lf R E A R T H R U S T R A CES A N D B E A R IN G Fig. 5 4 —In s ta llin g D is c h a rg e C ro sso ver T u b e P IS T O N S IN " S T A IR S T E P " P O S IT IO N BALL AN D F R O N T A N D REAR. A X IA L P L A T E F R O N T T H R U S T R A C ES A N D B E A R IN G S ________ f t ! ________________________ Fig. 5 2 —In stallin g 2n d A -6 Piston complete drawing the cylinder halves together. 9. Generously lubricate all moving parts with clean 525 viscosity refrigerant oil and check for free rotation of the parts. 10. Replace Fig. 5 5 --A -6 P istons P o sitio n ed in S ta ir-S te p A rra n g e m e n t the suction cross-over cover (Fig. 56). Compress the cover as shown to start it into the slot, and then press or carefully tap it in until flush on both ends. T R U C K SUP P - O V E R H A U L 1-22 A IR C O N D ITIO N IN G COMPRESSOR I : i. '' \ B U S H IN G -R IN G Fig. 5 7 —1nsta llin g O -R ing On D is c h a rg e C ross-over T u b e Fig. 5 6 -ln s ta llin g S u ctio n C ross-over C over A-6 COMPRESSOR INTERNAL M ECHA NISM Re-Install 1. Place internal mechanism on Internal Assembly Support Block J-21352, with rear-end of shaft in block hole. 2. Now install new O-ring and bushing on front-end of discharge cross-over tube (Fig. 57). The O-ring and bushing are Service parts only for internal mechanisms that have been disassembled in the field (see Fig. 53). l-ront R eed P late O il Return Slot 3. Install new dowel pins in front cylinder half, if previously removed. 4. Install front suction reed plate on front cylinder half. Align with dowel pins, suction ports, oil return slot, and discharge cross-over tube (Fig. 58). 5. Install front discharge valve plate assembly, aligning holes with dowel pins and proper openings in front suction reed plate (Fig. 59). Front discharge plate has a large diam eter hole in the center (Fig. 60). 6. Coat sealing surfaces on webs of compressor front head casting with 525 viscosity refrigerant oil. 7. Determine exact position of front head casting in relation to dowel pins on internal mechanism. M ark position of dowel pins on sides of front head assembly and on sides of internal mechanism with a grease pencil. Carefully lower front head casting into position (Fig. 62), making certain that sealing area around center bore of head assembly does not contact shaft as SUPPORT BLOCK J-21352 Fig. 5 8 —1n s ta llin g F ro n t S u c tio n Reed head assembly is lowered. Do not rotate head assembly to line up with dowel pins, as the sealing areas would contact reed retainers. 8. Generously lubricate new O-ring and angled groove at lower edge of front head casting with 525 viscosity refrigerant oil and install new O-ring into groove (Fig. 62). 9. Coat inside machined surfaces of compressor shell with 525 viscosity refrigerant oil and position shell on internal mechanism, resting on O-ring seal. T R U C K SUP P - O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-23 Front Discharge V alve I | Plate Assembly Front Head Casting Front Discharge Valve Plate Assembly SUPPORT BLOCK J-21352 F ig . 6 1—In s t a llin g F r o n t H e a d C a s tin g Fig . 5 9 - - ln s ta llin g F r o n t D is c h a r g e V a lv e P la te • Suction Reed Front H ead O -R in g Larger Dia. H o le Rear Discharge V a lv e Plate Front Discharge V a lv e Plate SUPPORT BLOCK J-21351 Fig . 6 0 --F ro n t a n d R e a r D is c h a r g e V a lv e P la te s 10. Using flat-side of a small screwdriver, gently position O-ring in around circumference of internal mechanism until compressor shell slides down over internal mechanism. As shell slides down, line up oil sump with oil intake tube hole (Fig. 63). 11. Holding Support Block, invert assembly and place back into Holding Fixture with front end of shaft down. Remove Support Block. 12. Install new dowel pins in rear cylinder half, if previously removed. 13. Install new O-ring in oil pick-up tube cavity. 14. Lubricate oil pick-up tube with 525 viscosity refrigerant oil and install into cavity, rotating compressor mechanism to align tube with hole in shell baffle (Fig. 64). 15. Install new O-ring and bushing on discharge cross-over tube (See Fig. 53). rear-end of F ig . 6 2 - F r o n t H e a d O -R in g In s ta lle d 16. Install rear suction reed over dowel pins, w ith slot TOW ARDS sump. 17. Install rear discharge valve plate assembly over dowel pins, w ith reed retainers UP . 18. Position inner oil pum p gear over shaft with previously applied identification mark UP. 19. Position outer oil pump gear over inner gear with previously applied identification mark UP and, when standing facing oil sump, position outer gear so that it meshes with inner gear at the 9-o’clock position, and resulting cavity between gear teeth is then at 3-o’clock position (Fig. 65). 20. Generously oil rear discharge valve plate assembly with 525 viscosity refrigerant oil around outer edge where large diam eter O-ring will be placed. Oil the valve reeds, TRUC K SUP P - O V E R H A U L 1-24 A IR C O N D ITIO N IN G COMPRESSOR IN N E R GEAR CAVITY BETWEEN] GEAR TEETH (3 O'C LO C K ) j O IL SUMP (6 O'C LO C K ) Fig . 6 3 - - In s ta llin g A -6 C o m p re s s o r S h e ll O IL DR A IN PLUG F ig . 6 5 --P o s itio n in g O il P u m p G e a rs 25. Install nuts on threaded shell studs and tighten evenly to 19-25 lb. ft. torque using a 0-50 lb. ft. torque wrench. 26. Invert compressor in Holding Fixture and install compressor shaft seal as described in “ Compressor Shaft Seal” Replacement procedure. F ig . 6 4 —I n s ta II i ng O il P ic k -U p T u b e pump gears, and area where sealing surface will contact rear discharge valve plate. 21. Using the 525 oil, lubricate new head to-shell O-ring and install on rear discharge valve plate, in contact with shell (Fig. 66). 22. Install suction screen in rear head casting, using care not to damage screen. 23. Coat sealing surface on webs of compressor rear head casting with 525 viscosity refrigerant oil. 24. Install rear head assembly over studs on compressor shell. The two lower threaded compressor mounting 27. Install compressor clutch coil and housing assembly as described in “Compressor C lutch Coil and Housing Asm .” Replacement procedure. 28. Install compressor pulley and bearing assembly as described in “Compressor Pulley and Bearing” Replacement procedure. 29. Install compressor clutch plate and hub assembly as described in “Compressor Clutch Plate and Hub Asm .” Replacement procedure. 30. A dd required am ount of 525 viscosity refrigerant oil. Refer to compressor oil charge, Figure 5 Section 1A, this manual. 31. Check for external and internal leaks as described in the following“Compressor Leak Testing” procedure. holes should be in alignment with the compressor sump. COMPRESSOR LEAK TESTING - EXTERNAL Make certain that suction screen does not drop out of place when lowering rear head into position (Fig. 67). A-6 and R-4 Compressors If rear head assembly will not slide down over dowels in internal mechanism, twist front head assembly back-and-forth very slightly by-hand until rear head drops over dowel pins. AND INTERNAL Bench-Check Procedure 1. Install Test Plate J-9625 on rear head of compressor. 2. A ttach center hose of gage manifold set on Charging Station to a refrigerant drum standing in an upright T R U C K SUP P - O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-25 F ig . 6 7 —-I n s ta 11i n g R e a r H ead 7. Loosen the manifold gage hose connections to the Gage A dapters J-5420 connected to the LOW and H IG H sides and allow the vapor pressure to release from the compressor. 8. Disconnect both Gage Adapters J-5420 from the Test Plate J-9625. F ig . 6 6 --A -6 S h e ll-T o -F ro n t H e a d 0 - R in g In s ta lla tio n position and open valve on drum. 3. Connect Charging Station H IG H and LOW pressure lines to corresponding fittings on Test Plate J-9625, using J-5420 Gage Adapters. 9. Rotate the complete compressor assembly ( not the crankshaft or drive plate hub ) slowly several turns to distribute oil to all cylinder and piston areas. 10. Install a shaft nut on the compressor crankshaft if the drive plate and clutch assembly are not installed. NOTE: Suction port of compressor has large internal opening. Discharge port has small internal opening into compressor. 11. Using a box-end wrench or socket and handle, rotate the compressor crankshaft or clutch drive plate on the crankshaft several turns to ensure piston assembly to cylinder wall lubrication. 4. Open LOW pressure control, H IG H pressure control and R E F R IG E R A N T control on Charging Station to allow refrigerant vapor to flow into compressor. 12. Connect the Charging Station H IG H pressure line or a H IG H pressure gage and Gage A dapter J-5420 to the Test Plate J-9625 H IG H side connector. 5. Using electronic-type Leak Detector, check for leaks at pressure relief valve, superheat switch, compressor shell to cylinder, compressor front head seal (and also rear head seal and oil charge port on A-6 compressor), and compressor shaft seal. A fter checking, shut off LOW pressure control and H IG H pressure control on Charging Station. 13. A ttach a A dapter J-5420 to the suction or LOW pressure port of the Test Plate J-9625 to open the schrader-type valve. 6. If an external leak is present, perform the necessary corrective measures and recheck for leaks to make certain the leak has been corrected. NOTE: Oil will drain out of the compressor suction port adapter if the compressor is positioned with the suction port down. 14. A ttach the compressor to the Holding Fixture J-25008-1, (R-4 compressor) and J-9396 (A-6 compressor), and clamp the fixture in a vise so that the compressor can be manually turned with a wrench. TRUC K SUP P - O V E R H A U L 1-26 A IR C O N D ITIO N IN G COMPRESSOR 15. Using a wrench, rotate the compressor crankshaft or drive plate hub 10 complete revolutions at a speed of approximately one revolution per second. NOTE: Turning the compressor at less than one revolution per second can result in a lower pump-up pressure and disqualify a good pumping compressor. 16. Observe the reading on the H IG H pressure gage at the completion of the tenth revolution of the compressor. The pressure reading for a good pumping compressor should be 50 p.s.i. or above for the R-4 and 60 p.s.i. or above for the A-6 compressor. A pressure reading of less than 45 p.s.i. for the R-4 or 50 p.s.i. for the A-6 would indicate one or more suction and/or discharge valves leaking, an internal leak, or an inoperative valve and the compressor should be disassembled and checked for cause of leak. Repair as needed, reassemble and repeat the pump-up test. Externally leak test with the electronic-type Leak Detector. 17. W hen the pressure pum p-up test is completed, release the air pressure from the H IG H side and remove the Gage A dapters J-5420 and Test Plate J-9625. 18. On the R-4, tilt the compressor so that the compressor suction and discharge ports are down. Drain the oil from the compressor. On the A-6, remove oil charge screw and drain the oil sump. 19. Allow the compressor to drain for 10 minutes, then charge with the proper am ount of oil. The oil may be poured into the suction port. NOTE: If further assembly or processing is required, a shipping plate or Test Plate J-9625 should be installed to keep out air, dirt and moisture until the compressor is installed. R4-COMPRESSOR OVERHAUL GENERAL When servicing a compressor, it is essential that steps be taken to prevent dirt or foreign material from getting on or into compressor parts and system during disassembly or reassembly of compressor. Clean tools, a clean workbench and a clean work area are very im portant for proper service. The compressor connection areas and exterior of compressor should be cleaned off as much as possible prior to any "on vehicle" repairs or removing compressor for workbench service. The parts must be kept clean at all times and any parts to be reassembled should be cleaned with clean solvent (trichlorethylene, or Stoddard solvent) and dried with dry air. W hen necessary to use a cloth on any part, it should be of a non-lint producing type. Refer to Figure 68 for the exploded view of the compressor parts and nomenclature. When a compressor is removed from the vehicle for servicing, the am ount of oil remaining in the compressor should be drained through compressor suction-discharge ports and measured. This oil should then be discarded and new oil added to the compressor before compressor is again placed in operation on vehicle. Refer to Figure 5, Section 1A of this manual for compressor oil charge. If for any reason the R-4 compressor air conditioning hose assembly is removed from the compressor, care must be taken to insure that the hose plate is fully seated to the compressor during re-installation. Should the plate be cocked and the retainer bolt driven, metal flanges in the O-Ring cavities could damage the seal surface of the compressor. Some service operations can be performed without disturbing the internal mechanism, completely removing the compressor from vehicle or discharging the system. Among them are replacement of the clutch drive plate and hub assembly, clutch rotor and bearing assembly and clutch coil and pulley rim where "on vehicle" space permits. The system must be discharged, evacuated and charged to replace the compressor shaft seal, pressure relief valve and superheat switch whether the compressor is removed from vehicle or not. See Evacuation and Charging Procedure. The service operations shown in the following procedure are based on bench overhaul with compressor removed from vehicle. For those operations possible to be performed with compressor "on the vehicle", the procedure is essentially the same. The procedures are basically in order of the normal sequence of removal for the accessibility of the components. When necessary to adjust the compressor belt tension, DO NOT pry on the compressor shell, lift at square hole on the compressor m ounting bracket. It is recommended that compressor holding fixture J-295008-1 (Fig. 69) be used for all "workbench" procedures to keep the compressor assembly off the workbench and help prevent any possible dirt contam ination of parts. The compressor holding fixture may be clamped in a vise with shaft end of compressor in a vertical, horizontal or down position for service, depending on service to be performed. TRUC K SUPP • O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-27 11 / m 1. Screw 13. S u p e r h e a t S w itch 24. B e lle v ille W a s h e r 2. L o c k in g W a s h e r 14. O -R in g 25. O -R in g 3. P u lle y Rim 15. P ressure R e lie f V a lv e 26. S h e ll Assy. 4. C o il a n d H o u s in g Assy. 16. O -R in g 27. R in g S e a l 5. R otor B e a rin g 17. S crew 28. M a in B e a rin g 6. R otor a n d B e a rin g Assy. 18. S h ip p in g P la te 29. F ro n t H e a d Assy. 7. R e ta in in g R ing 19. O -R in g 30. S cre w a n d W a s h e r Assy 8. C lu tc h D rive Assy. 20. R e ta in in g R ing 9. 2 1 . V a lv e P la te Assy. C lu tc h H u b Key 10. S h a ft N u t 22. 11. C a p 2 3 . T h ru s t W a s h e r 12. C y lin d e r a n d S h a ft Assy. 31. O -R in g 32. S h a ft S e a l 33. Seal Seat 34. R e ta in in g R ing R e ta in in g R in g F ig . 6 8 - R a d ia l F o u r C y lin d e r C o m p re s s o r - E x p lo d e d V ie w TRUC K SUP P - O V E R H A U L 1-28 A IR C O N D ITIO N IN G COMPRESSOR D ISC HAR G E PORT S U C T IO N PORT SUPERHEAT S W ITC H J -9 3 9 9 CLUTCH ASSEMBLY H IG H PRESSURE RELIEF VALVE Fig. 6 9 —I n s tallin g H o ld in g Fixture J -2500 8-1 COMPRESSOR CLUTCH PLATE AND HUB ASSEMBLY Removal 7 0 -R e m o v in g S h a ft L o ckn u t 1. A ttach compressor to holding fixture, J-25008-1 (Fig. 69) and clamp fixture in a vise. 2. Keeping clutch hub from turning with clutch hub holding tool J-25030, remove and discard shaft nut using Thin Wall Socket J-9399 (Fig. 70). 3. Thread clutch plate and hub assembly remover J-9401 into hub. Hold body of tool with a wrench and turn center screw into J-9401 remover to remove clutch plate and hub assembly (Fig. 71). 4. Remove the shaft key. Installation 1. Install shaft key into hub key groove (Fig. 72). Allow key to project approximately 3/16" out of key way. Shaft key is curved slightly to provide an interference fit in shaft key groove, to perm it key projection w ithout falling out. 2. Be sure frictional surface of clutch plate and clutch rotor are clean before installing clutch plate and hub assembly. 3. Align shaft key with shaft key way and assemble clutch plate and hub assembly on compressor shaft. CAUTION: To a void internal damage to compressor, do not drive or pound on clutch hub or shaft. 4. Place spacer bearing J-9480-2 on hub and insert end of clutch plate and hub assembly installer J-9480-1 through spacer J-9480-2 and thread tool onto end of compressor shaft (Fig. 73). 5. Hold hex portion of tool body with a wrench and tighten ^ center screw to press hub onto shaft until there is a .020 to .040 inch air gap between the frictional surfaces of clutch plate and clutch rotor (Fig. 6). 6. Install a new shaft nut with the small diameter boss of nut against crankshaft shoulder, using special thin wall socket J-9399. Hold clutch plate and hub assembly with clutch hub holding tool J-25030 and tighten to 8-12 foot pounds torque. COMPRESSOR SHAFT SEAL ASSEMBLY Removal W hen replacing shaft seal assembly, it will be necessary to discharge the refrigerant from the system before replacing shaft seal assembly or removing compressor from vehicle. 1. Discharge the system and remove clutch plate and hub assembly as described under "Compressor Clutch Plate and Hub Assembly". 2. Remove shaft seal seat retainer ring using snap ring pliers J-5403. 3. Thoroughly clean the inside of compressor neck area surrounding compressor shaft, seal seat and shaft, to remove all dirt and foreign material before removing seal seat. 4. Insert seal seat remover and install tool J-23128 (Fig. 74) over the shaft into the recessed area of seal seat and tighten tool clockwise to securely engage knurled tangs of tool with the seal seat. Remove seal seat with a twisting and pull motion. D iscard seat. 5. Insert seal remover and installer J-9392 (Fig. 75) over shaft and engage shaft seal by pressing downward on tool to overcome shaft seal spring pressure and turn tool clockwise to engage seal assembly tabs with tangs of tool. Remove seal assembly by pulling straight out from compressor shaft. Discard seal. T R U C K SUP P - O V E R H A U L AIR C O N D IT IO N IN G COMPRESSOR 1-29 Fig. 7 3 —I nsta Ming C lu tch P late and H ub A sse m b ly Pig. 7 4 --R e m o v in g S e a l S e a t Fig. 7 2 —In s ta llin g S h a ft Key 6. Remove seal seat "O" ring from compressor neck using tool J-9553. Discard "O" ring. remover and installer J-9392, seal protector J-22974 and "O" ring installer J-21508 are clean internally and externally. The seal seat "O" ring, shaft seal and seal seat should be dipped in clean 525 Viscosity oil and not handled any more than is absolutely necessary by hand, particularly the mating surfaces. Any dirt or lint on sealing surfaces could cause a seal leak or seal damage. Installation 1. Dip new seal seat "O" ring in clean 525 Viscosity oil and assemble onto "O" ring installer J-21508 (Fig. 76). Inspect the inside of compressor neck and shaft area for any lint, dirt or foreign material and be sure these areas are perfectly clean before installing new seal parts. Be sure seal 2. Insert "O" ring installer J-21508 into the compressor neck until the tool "bottom s". Lower the movable slide of "O" ring installer to release "O" ring into seal seat TR U C K SUP P - O V E R H A U L 1-30 A IR C O N D ITIO N IN G COMPRESSOR shaft. Slowly turn the tool clockwise while applying light pressure until seal engages the flats of compressor shaft and can be seated into place. R otate tool J-9392 counterclockwise to disengage from seal tabs and remove tool. 5. A ttach ceramic seal seat to the seal seat remover and installer J-23128 and dip ceramic seat in clean 525 viscosity oil to coat seal face and outer surface. Carefully install seat over compressor shaft and seal protector J-22974 and push seat into place with a rotary motion. Remove tools J-23128 and J-22974. 6. Install new seal seat retainer ring with snap ring pliers J-5403. 7. Leak test compressor as described under "Leak Testing the Compressor" and correct any leaks found. 8. Reinstall clutch plate and hub assembly as described under "Compressor Clutch Plate and Hub Assembly". COMPRESSOR CLUTCH ROTOR & BEARING Compressor Clutch Rotor & Bearing Fig. 75 --R e m o v in g S h a ft S eal 1. Remove the clutch plate and hub assembly as described under "Compressor Clutch Plate and Hub Assembly". 2. Remove rotor and bearing assembly retaining ring using snap ring pliers J-6083 (Fig. 77). M ark the location of clutch coil terminals. If clutch rotor a n d /o r rotor bearing only are to be replaced, bend the lockwashers away from pulley rim m ounting screws (Fig. 78) and remove the six m ounting screws and special lockwashers before proceeding with Step 3. Discard special lockwashers. 3. Install rotor and bearing puller guide J-25031-1 over the end of compressor shaft and seat on the front head of compressor (Fig. 78). 4. Install rotor and bearing puller J-25031-2 down into rotor until the puller arms engage the recessed edge of rotor hub. Hold puller and arms in place and tighten puller screw against puller guide to remove clutch rotor and assembly parts (Fig. 79). If pulley rim mounting screws and washers were removed in Step 2, only clutch rotor and bearing assembly will be removed for replacement. Fig. 7 6 --In s ta llin g S e a l S e a t " 0 " Ring "O" ring groove. R otate installer tool to seat "O" ring and remove tool. Inspect the internal neck area for cleanliness and proper "O" ring positioning. 3. Dip new shaft seal "O" ring and seal face in clean 525 Viscosity oil and carefully engage shaft seal assembly with locking tangs of seal remover and installer J-9392 (Fig. 8). 4. Install shaft seal protector J-22974 over the end of compressor shaft and slide shaft seal onto compressor The clutch coil and housing assembly is pressed onto front head of compressor with an interference fit and will not be removed unless pulley rim mounting screws are left securely in place and pulley rim pulls coil and housing assembly off with total clutch rotor and pulley rim assembly (Fig. 80). CLUTCH ROTOR BEARING REPLACEMENT Removal 1. Perform "Compressor Clutch R otor and Bearing Assembly Removal" and remove the pulley rim mounting screws as described in Step 2. 2. Place rotor and bearing assembly on blocks (Fig. 82) and drive bearing out of rotor hub with rotor bearing remover and rotor assembly installer J-25029. It will not be necessary to remove the staking at the rear of the TR U C K SUP P - O V E R H A U L AIR C O N D IT IO N IN G COMPRESSOR 1-31 J -2 5 0 3 1 -2 Fig. 7 7 ~ R e m o v in g B e a rin g R e ta in in g Ring Fig. 7 9 --ln s ta llin g R o to r and B earin g P uller J-25031-1 LO C K IN G WASHER SCREW Fig. 7 8 --ln s ta llin g R otor and B earin g P u lle r G u id e rotor hub to remove the bearing. See Figure 81. In s ta lla tio n 1. Place rotor and hub assembly face down on a clean, flat and firm surface (Fig. 83). 2. Align new bearing squarely with hub bore and using pulley and bearing installer J-9481 with Universal Handle J-8092, drive bearing fully into hub. The tool will apply force to outer race of bearing. Fig. 8 0 --C lu tc h C oil an d H o u sin g A sse m b ly 3. Stake bearing in place with a 45° angle punch (Fig. 81) but do not stake too deep (.045 - .055 inch) and possibly distort the outer race of bearing. Use new stake locations 120° apart. D o not use old stake locations. 4. Recommended Method Press rotor and bearing assembly onto the front head of the compressor, using R otor and Bearing Assembly Installer J-25029 (Fig. 84). The Installer will apply force to the inner race of the rotor bearing when installing the TRUCK SUPP - O VERH AUL 1-32 A IR C O N D IT IO N IN G COMPRESSOR BEARING STAKE LOCATIONS Fig. 8 1 ~ B e a r in g S ta k e L o catio n s assembly onto the front head. A lternate method Reassemble the rotor and bearing assembly to the front head of the compressor using Rotor Bearing Remover and Rotor Assembly Installer J-25029. W ith Installer assembled to the Universal Handle J-8092 as shown in Fig. 85, force w ill be applied to the inner race of the bearing when installing the assembly on the front head of the compressor. 5. Install rotor and bearing using Snap Ring Pliers J-6083. 6. Assemble and fully seat pulley rim to clutch rotor and bearing assembly as shown in Figure 84, using Loctite RC-75 or equivalent on screw threads and use new lockwashers. Do not torque m ounting screws to final torque limits until pulley rim is checked to be rotating "in line". 7. Tighten pulley rim m ounting screws to a 100 inch pounds torque and lock screw heads in place as shown in Figure 84. 8. Assemble clutch plate and hub assembly as described under "Compressor Clutch Plate and Hub Assembly". CLUTCH COIL AND PULLEY RIM REPLACEMENT Removal 1. Perform "Com pressor Clutch R otor and Bearing Assembly Removal" but do not loosen or remove pulley rim m ounting screws until clutch rotor, coil and pulley rim assembly have been removed from front head in Step 4. 2. Remove pulley rim m ounting screws and slide pulley rim off rotor and hub assembly. The pulley rim and Fig. 8 2 --R e m o v in g C lu tch R otor B earin g clutch coil are replaceable at this point. Installation 1. Assemble clutch coil, pulley rim and clutch rotor and bearing assembly as shown in Figure 80, using Loctite RC-75 or equivalent on screw threads and using new lockwashers, but do not lock screw heads in place. 2. Place assembly on neck of front head and seat into place using rotor bearing remover and rotor assembly installer J-25029 as shown in Figure 84. Before fully seating the assembly on front head, be sure the clutch coil terminals are in the proper location in relation to compressor and that the three protrusions on the rear of the clutch coil align with the locator holes in front head. 3. Install rotor and bearing assembly retaining ring and reassemble clutch plate and hub assembly. 4. R otate pulley rim and rotor to be sure pulley rim is rotating "in line" and adjust or replace as required. Tighten pulley rim m ounting screws to 100 inch pounds torque and lock screw heads in place. TR U C K S UPP - O V E R H A U L A IR C O N D IT IO N IN G COMPRESSOR 1-33 S P A C E R -U S E PIECE O F F L A T S TO C K J 25029 ROTO R AND B E A R IN G A S M . IN S T A L L E R J 25008-1 H O L D IN G F IX T U R E Fig. 8 4 —In s ta llin g R otor and B e a rin g A ss e m b ly Fig. 8 3 ~ ln s ta llin g C lutch R o to r B earin g FRONT HEAD AND M A IN BEARING ASSEMBLY R em oval 1. Remove clutch rotor and bearing assembly but do not loosen or remove pulley rim m ounting screws and remove clutch rotor, coil and pulley rim assembly as a total assembly. 2. Remove compressor shaft seal. 3. Remove the four front head mounting screws (Fig. 86) and remove front head assembly and discard seal ring. At this point front head and bearing assembly, front head seal ring (Fig. 87) or the Belleville and thrust washers may be replaced. Installation 1. Check front head and compressor cylinder area for any dirt or lint and install a new thrust washer kit if required. 2. Dip new front head seal ring in 525 Viscosity oil and install seal in seal groove of front head (Fig. 87). 3. Position oil hole in front head to be "up" when assembled to compressor cylinder to correspond with "up" position of compressor. Install front head on compressor shaft. Be sure seal ring stays in place and front head seats correctly to cylinder. Tighten front head mounting screws to 18-22 foot pounds. 4. Install a new compressor shaft seal. 5. Install clutch rotor and bearing assembly, clutch coil and pulley rim assembly to front head (Fig. 84). Before fully seating the assembly on front head be sure clutch coil terminals are in the proper location in relation to compressor and that the three protrusions on rear of clutch coil align with the locator holes in front head. 6. Install rotor and bearing assembly retaining ring and reassemble clutch plate and hub assembly. 7. Leak test compressor as described under "Leak Testing the Compressor" and correct any leaks found. T R U C K SUP P - O V E R H A U L 1-34 A IR C O N D IT IO N IN G COMPRESSOR FR ON T H EAD J-8092 J -2 5 0 2 9 Fig. 8 6 -R e m o v e F ro n t H ead A sse m b ly H O L D IN G FIXTURE J-2 5 0 0 8 -1 O IL HOLE TO SHAFT SEAL AREA F R O N T H EA D SEAL R IN G M A IN B E A R IN G Fig. 8 5 - A lt e r n a t e In s ta lla tio n o f R-4 R otor and B earin g A s s e m b ly THRUST AND BELLEVILLE WASHER REPLACEMENT 1. Remove two thrust and one belleville washer from compressor shaft. N ote the assembled position of the washers. 2. Install a new thrust washer on compressor shaft with thrust washer tang pointing up (Fig. 88). 3. Install the new belleville washer on shaft with the high center of the washer up (Fig. 88). 4. Install the remaining thrust washer on shaft with the tang pointing down (Fig. 88). THR UST A N D BELLEVILLE W A S H E R S 5. Lubricate the three washers with clean oil (525 Viscosity) and assemble front head to cylinder. Fig. 8 7 —1n s tallin g F ro n t H ead M A IN BEARING REPLACEMENT Removal 1. Remove front head assembly. 2. Place front head assembly on two blocks (Fig. 89) and using main bearing remover J-24896 drive bearing out of front head. 2. Align new bearing and bearing installer J-24895 squarely with bearing bore of front head and drive bearing into front head (Fig. 90). The tool J-24895 must seat against front head to insert bearing to proper clearance depth. Installation 1. Place front head with neck end down on a flat, solid surface. 3. Assemble front head to cylinder and complete the assembly. TR U C K SUP P - O V E R H A U L AIR C O N D IT IO N IN G COMPRESSOR 1-35 J-24895 M A IN BEARING BELLEVILLE W A SH ER THRUST W A SH ER Fig. 9 0 --I nsta lling M a in B earin g Fig. 8 8 --R e p la c in g T h ru s t and B e lle v ille W a s h e rs SHELL R ETAIN IN G STRAP J -2 4 8 9 6 FRONT HEAD ill \VJH ..iL r Fig. 9 1 -R e le a s in g R eta in in g S tra p Fig. 8 9 -R e m o v in g M a in B earin g COMPRESSOR SHELL, CYLINDER "O" RING AND VALVE PLATE REPLACEMENT The clutch plate and hub assembly, the clutch rotor and bearing assembly, the clutch coil and pulley rim must be removed before compressor shell can be removed or replaced. The location of clutch coil term inals should be marked for reference on reassembly. Allow compressor to cool to room tem perature before attem pting to remove compressor shell as greater force will be required to remove the compressor shell when hot due to metal expansion difference between the aluminum cylinder and steel compressor shell. 1. Pry shell retaining strap away from cylinder and position the strap high enough to clear cylinder as shell is removed (Fig. 91). 2. Remove compressor holding fixture J-25008-1 and reverse holding fixture step block protrusions engaging compressor shell. Install medium length bolts through holding fixture and thread them into compressor cylinder until the step of the fixture protrusions contact TR U C K S UPP - O V E R H A U L 1-36 A IR C O N D ITIO N IN G COMPRESSOR Fig. 9 2 --R e m o v in g S hell A sse m b ly Fig. 9 3 -R e m o v in g V a lv e P late compressor shell, finger tight, both sides (Fig. 92). Check to be sure the step protrusions do not overlap the cylinder but will pass both sides. 3. Using a wrench, alternately tighten each bolt approximately 1/4 turn to push shell free of "O" rings on cylinder. If one screw appears to require more force to turn than the other, immediately turn the other screw to bring the screw threading sequence in step or the shell will be cocked and made more difficult to remove. Norm al removal does not require m uch force on wrench if the screws are kept in step while turning. The shell can be removed by hand as soon as shell is free of shell to cylinder "O" rings. Do not turn screws any further than necessary to release shell. P IS T O N A N D REED A S S E M B L Y 4. Remove compressor shell, remove holding fixture J-25008-1 from compressor, reverse fixture to again hold compressor by the opposite side using the short length screws. At this point the valve plate retainer ring may be removed using internal snap ring pliers, J-4245 (Fig. 93) and remove the compressor valve plate (Fig. 94) for replacement or piston inspection. Fig. 9 4 -ln s p e c tin g Piston and Reed A sse m b ly Installation 1. Remove old cylinder to shell "O" rings and discard. Check compressor assembly and interior of compressor shell to be sure they are free of lint or dirt. 2. Dip a cylinder to shell "O" ring in 525 Viscosity oil and install in rear "O" ring groove of cylinder. Be careful in moving "O" ring across cylinder surface to prevent damaging "O" ring. 3. Dip remaining cylinder to shell "O" ring in oil and install it in front "O" ring groove of cylinder. 4. Place compressor shell on cylinder and rotate retaining strap to its original location (Fig. 92). 5. A ttach shell installing fixture J-25008-2 to the holding fixture J-25008-1, using the long bolts and plate washers of tool set. TRUC K SUP P - O V E R H A U L AIR C O N D IT IO N IN G COMPRESSOR 1-37 a hammer. 9. Remove shell installing fixture J-25008-2 and leak test compressor. OIL CHARGE The radial four cylinder compressor is charged with 6.0 ounces of 525 viscosity oil. During normal operation a certain amount of oil will circulate with the Refrigerant 12 (R-12) in the system. When necessary to replace a system component it is recommended that oil be added to the system in accordance to the following procedure. If compressor is operable, idle vehicle for 10 minutes with the A /C controls set for Maximum Cooling and High Blower prior to discharging the system. Add additional oil as indicated in Section 1A of this manual. Oil Charge-Compressor Replacement 1. Gravity drain oil from a new compressor. Position compressor with shaft end "u p ” and drain compressor suction and discharge ports. The compressor should gravity drain for 10 minutes. Fig. 9 5--I nsta I ling S h ell A s s e m b ly Align the step projections of shell installing fixture J-25008-2 to contact compressor shell evenly both sides. 6. Push compressor shell as close to "O" ring (Fig. 95) as possible by hand and check for equal alignment of shell around cylinder. Tighten fixture screws finger tight. 7. Using a wrench, alternately tighten each bolt approximately 1/4 turn to push compressor shell over "O" rings and back against shell stop flange at the rear of compressor cylinder. If one screw appears to require more force to turn than the other, immediately turn the other screw to bring the screw threading sequence in step or the shell will be cocked and made more difficult to install. N orm al installation does not require m uch force on wrench if screws are kept in step while turning. 8. When shell is seated against the stops, bend shell retaining strap down into place by tapping gently with Add additional oil as indicated in Section 1A of this manual. When necessary to flush system with R - ll, drain assembly and blow dry with air prior to the installation of a new compressor. It is not necessary to drain oil from the replacement compressor. 2. The refrigerant 12 (R-12) is to be slowly discharged from the system. 3. Remove original compressor from vehicle, gravity drain the oil from compressor as in Step 1 and determine the am ount of oil drained from the original compressor. Refer to the oil usage chart in the service section of this manual for proper am ount of oil to be added. SYSTEM PERFORMANCE EVALUATION Wrhen system performance, efficiency and proper oil charge is in doubt and must be evaluated accurately, it is recommended that the system be flushed with R -11 and the exact oil charge (6 ounces) of 525 viscosity oil be added to the compressor prior to any further checks of the system. TR U C K S UPP - O V E R H A U L 1-38 A IR C O N D IT IO N IN G COMPRESSOR SPECIAL TOOLS 1. 2. 3. 4. 5. 6. 7. 8. 9. J -8 3 9 3 J -2 4 0 9 5 J -5 4 5 3 J -9 4 5 9 J -2 5 4 9 9 J -5 4 2 0 J -2 5 4 9 8 J -6 0 8 4 J -8 4 3 3 J -9 3 9 5 J -2 3 5 9 5 10. J-6 2 7 1 -0 1 C h a rg in g S ta tio n O il In d u c e r G o g g le s 7 /1 6 "-2 0 9 0° G a u g e Line 3 /8 " -2 4 A d a p te r 7 /1 6 "-2 0 S tra ig h t G a u g e Line 3 /8 " A d a p te r Leak D e te cto r P u lle r P u lle r P ilo t R e frig e ra n t C an V a lv e (S id e -T a p ) R e frig e ra n t C an V a lv e (T o p -T a p ) 11. 12. 13. 14. J-5 4 2 1 -0 2 J-5 40 3 J-6 4 3 5 J -9 3 9 6 15. J -2 5 0 3 0 16. J-9 40 3 17. J-9 3 9 9 18. J-9401 19. J-9 48 0 -0 1 2 0. J-9 3 9 2 2 1. J-2 3 1 2 8 P ocket Th e rm om e te rs (2) N o . 21 S n a p Ring P liers N o . 26 S n a p R ing P liers C om p re sso r H o ld in g F ix tu re C om p re ssin g F ix tu re C lu tc h H u b H o ld in g Tool 9 /1 6 " Thin W a ll Socket H u b a n d D rive P la te A sse m bly Rem over H u b a n d D rive P la te A sse m bly In s ta lle r S eal Rem over S e a l S e a t Rem over 22. 23. 24. 25. J -9 3 9 8 J-9481 J -8 0 9 2 J -2 1 3 5 2 29. J -2 1 5 0 8 P u lle y B e a rin g Rem over P u lle y a n d B e a rin g In s ta lle r H a n d le In te r n a l A sse m bly S u p p o rt B lock O il P ic k u p T u b e Rem over N e e d le B e a rin g In s ta lle r S e a l S e a t " O " Ring Rem over S e a l S e a t " O " Ring 30. J -2 2 9 7 4 3 1 . J -9 6 2 5 3 2 . J -9 4 0 2 In s ta lle r S h a ft S e a l P ro te c to r Pressure Test C o n n e c to r Parts T ra y 26. J -5 1 3 9 27. J -9 4 3 2 2 8 . J -9 5 5 3 -0 1 Fig. 9 6 - A i r C o n d it io n in g S p ec ia l T o ols , \i T R U C K SUP P - O V E R H A U L S E C T IO N 3 FRONT AXLE K10, K20 FRONT AXLE INNER OIL SEAL INSTALLATION TOOL The procedure for oil seal replacement on page 3-1 of the 1974 Overhaul Manual should be revised to include special tool J -25 111 for installing the oil seals. The seals are illustrated as item 28 in figure 1 below: Fig. 1 ~ ln n e r O il S eal S E C TIO N 4 REAR AXLE DIFFERENTIAL OVERHAUL G E N E R A L IN F O R M A T IO N Except for one modification (in the D ana 10-1/2" Axle), all overhaul procedures found in section 4 of the 1974 Overhaul M anual are applicable to 1976 differentials. Two items should be noted: 1. The differential case (item 14 on page 4-55) is now a one-piece design. 2. The pinion spider (item 21) is now a pinion shaft, using two pinion gears rather than four. PINION DEPTH SETTING USE OF DIAL INDICATOR • Note the 8-1/2" axles on G10 models in figure 1. Procedures for these units are listed under "Passenger C ar 8-1/2" Ring Gear" in the 1974 Overhaul manual. It is im portant to use a dial indicator correctly when determining pinion depth requirements. • The 6 2 0 0 # D ana differential is overhauled in an identical m anner to the 7 5 0 0 # Dana. Be sure to record the number indicated by the indicator needle; do not record the am ount of travel of the needle. DANA 1 0 -1 /2 RING GEAR DIFFERENTIAL Modification The differential shown on page 4-55 of the 1974 Overhaul M anual has been modified for some vehicles . For these modified units, A fter "zeroing" the dial indicator on the highest point of deflection on the gauge plate, the indicator probe is swung off the gauge plate, allowing the needle to move. The number which the needle points toward is the correct shim thickness required for a nominal pinion. See figure 2. TR U C K S U P P - O V E R H A U L 4-2 REAR AXLE DIFFER EN TIA L SOURCE TYPE /C A PA C ITY RING GEAR SIZE C10 C hevrolet S a lis b u r y /3 7 5 0 # * K10 C h evrolet S a lis b u r y /3 7 5 0 # 8 -7 /8 ” K10 C h evrolet S a lis b u r y /4 0 0 0 # 8 - 7 /8 '' P10 C h e v ro le t S a lis b u ry /3 5 0 0 # 8 -7 /8 ” G10 C h evrolet S a lis b u ry /3 1 0 0 # 8 -7 /8 ” G10 C h e v ro le t S a lis b u ry /3 1 0 0 # 8 -1 /2 ” MODEL 8 - 7 /8 " C20 (Except Crew Cab) C hevrolet S a lis b u r y /5 7 0 0 # 1 0 -1 /2 ” C20 (Crew Cab) C h e vro le t S a lis b u r y /7 5 0 0 # 1 0 -1 /2 ” K20 C h e v ro le t S a lis b u ry /5 7 0 0 # 1 0 -1 /2 ” P20 C h e v ro le t S a lis b u ry /5 7 0 0 # 1 0 -1 /2 ” G20 C h e vro le t S a lis b u r y /3 5 0 0 # 8 - 7 /8 " "ZE R O " THE IN D ICATO R, WITH THE PROBE ON THE HIGH POINT OF THE GAUGING SURFACE. SWING THE PROBE OFF THE GAUGE PLATE. (Except C30 C30 Dual Wheel Camper) (Dual Wheel Camper) P30 p (With H22/H 23) G30 _„n 030 ___ G30 (Dual Wheel) (Dual Wheel) C h e vro le t S a lis b u ry /7 5 0 0 # 1 0 -1 /2 " Dana S a lis b u ry /7 5 0 0 # 1 0 -1 /2 " C h e v ro le t S a lis b u r y /7 9 0 0 # 1 0 -1 /2 ” C h e v ro le t B a n jo /1 1 ,0 0 0 # 1 2 -1 /4 " C h e v ro le t S a lis b u r y /5 7 0 0 # 1 0 -1 /2 " Dana S a lis b u ry /6 2 0 0 # 9 -3 /4 ” Dana S a lis b u ry /7 5 0 0 # 1 0 -1 /2 " Fig. 1 -A x le C h a rt THE IN D IC A TO R NEEDLE WILL MOVE TOWARD. . . . THE PROPER NUMBER, WHICH INDICATES THE REQUIRED SHIM FOR A NO M INAL PINION. THIS NUMBER IS THE CORRECT SHIM THICKNESS FOR A N O M IN A L PINION. Fig. 2 - C o r r e c t Use o f D ial In d ic a to r TR U C K SUP P - O V E R H A U L S E C T IO N 5 BRAKES The 1976 brake boosters are essentially the same as those described in the 1974 Overhaul M anual, with the following exceptions. DELCO SINGLE DIAPHRAGM BOOSTER POWER PISTON GROUP ASSEMBLY The assembly procedure is the same as outlined in the 1974 Overhaul Manual; however, when assembling the support plate to the power piston be sure to press down and rotate the support plate clockwise until the locking lugs o f the power piston come against the stops on the support plate. GAUGING All 1976 master cylinders incorporate shallow socket prim ary pistons; therefore, all gauging procedures should incorporate the use of Gauge J-22647. DELCO SINGLE AND DUAL DIAPHRAGM BOOSTERS STAKING FRONT AND REAR CYLINDER HOUSINGS Delco single and dual diaphragm booster cylinder housings are staked in two places 180° apart (fig. 1). When reassembling cylinder housings, be sure the housings are fully locked. Using a 1/8" diameter rod (or equivalent tool), stake the two housings in two places 180° apart. CAUTION: The interlock tabs should not be used for staking a second time; stake two of the remaining tabs. W hen all tabs have been staked once, the housing must be replaced. Fig. 1 -D e lc o B o o ste r W ith S ta k e d T a b s T R U C K SUP P - O V E R H A U L 5-2 BRAKES BENDIX HYDRAULIC BRAKE BOOSTER (HYDRO-BOOST) IN D E X Disassembly............................................................................................5-2 Cleaning and Inspection.................................................................... ..5-3 A ssem bly............................................................................................... .5-4 OVERHAUL OPERATIONS The Bendix H ydraulic Brake Booster utilizes the hydraulic pressure supplied by the power steering pump to provide power assist for brake applications (fig. 3). The dual master cylinder is m ounted to the output push rod end of the booster. The procedures below include removal of the mounting bracket even though it is not necessary to remove the bracket for overhaul of the internal assembly. Disassembly (Fig. 4) 1. Secure the booster in a vise (bracket end up) and use a ham m er and chisel to cut the bracket nut that secures the mounting bracket to the power section (cut the nut at the open slot in the threaded portion of the housing). Be careful to avoid damage to the threads on the booster hub. Spread the nut and remove it from the power section. Then remove the mounting bracket. 3. Place Tool J-24569 around the pedal rod and resting on the input rod end as shown in Figure 5. 4. Place a punch (or similar tool) through the pedal rod from the lower side of Tool J-24569. Push the punch on through to rest on the higher side of the tool. Lift up on the punch to shear the pedal rod retainer; remove the pedal rod. 5. Remove the rem nants of the rubber grommet from the groove near the end of the pedal rod and from the groove inside the input rod end. 6. W ith a small screwdriver, pry the plastic guide out of the output push rod retainer. Disengage the tabs of the spring retainer from the ledge inside the opening near the master cylinder mounting flange of the booster. Remove the retainer and the piston return spring from the opening. 7. Pull straight out on the output push rod to remove the push rod and push rod retainer from inside the booster piston. PRESSURE PORT RETURN PORT 2. Remove the pedal rod boot (if equipped) by pulling it off over the pedal rod eyelet. PEDAL ROD ACCUMULATOR 8. Press in on spool plug, and using a small screwdriver, remove the snap ring from the housing bore. 9. Use pliers to remove the spool plug from the bore. Remove the "O" ring seal from the plug; discard the "O" ring. Remove the spool spring from the bore. 10. Place the booster cover in a vise equipped with soft jawed devices. Using special socket J-25085, remove the five screws that secure the booster housing to the cover. MOUNTING BRACKET OUTPUT PUSH ROD BOOSTER POWER SECTION Fig. 3- -B end ix H yd ro -B o o s t B ra ke Boo ste r 11. Remove the booster assembly from the vise and while holding the unit over a pan, separate the cover from the housing. Remove the large seal ring from the groove in the cover; discard the seal. 12. Remove the input rod and piston assembly, and the spool assembly from the booster housing. TRUC K SUP P - O V E R H A U L BRAKES 5-3 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Pedal Push Rod Pedal Rod R etainer B oot B racket N u t Linkage B racket Booster Cover Cover to Housing Seal In p u t Rod Seals In p u t Rod and Piston Assy. Spool A ssem bly 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. Plunger Seat " 0 " Ring Seal Plunger Spacer Check V a lv e Ball A c c u m u la to r C heck V alve " 0 ” Ring Seal Piston Seal Booster Housing T u b e Seat Inserts 21 . 22 . 23 . 24 . 25 . 26 . 27. 28. 29 . O u tp u t Push R od Push Rod R etainer S pool Spring Plug " 0 ” Ring S pool Plug Snap Ring Piston R etu rn Spring Spring R etainer Housing to C over Bolts Fig. 4 - P o w e r B o o ste r C o m p o n e n ts (T y p ic a l) 13. Remove the input rod seals from the input rod end, and the piston seal from the piston bore in the housing; discard the seals. 14. Remove the plunger, seat, spacer and ball from the accum ulator valve bore in the flange of the booster housing. Remove the "O" ring from the seat; discard the "O" ring. 15. Thread a screw extractor into the opening in the check valve in the bottom of the accum ulator valve bore, and remove the check valve from the bottom of the bore. Discard the check valve and "O" ring. NOTE: Using a screw extractor damages the seat in the check valve. A new charging valve kit must be installed whenever the check valve is removed from the accum ulator valve bore. 16. Use a 1/4" or a 5/16" spiral flute type screw extractor to remove the tube seats from the booster ports. Cleaning and Inspection 1. Clean all metal parts in a suitable solvent. Be careful to avoid losing small parts. 2. Inspect the valve spool and the valve spool bore in the booster housing for corrosion, nicks, scoring or other damage. Discoloration of the spool or bore, particularly in the grooves, is not harmful and is no cause for concern. 3. If the valve spool or the valve spool bore has nicks or scoring that can be felt with a fingernail, particularly on the lands, the entire booster should be replaced as an assembly. NOTE: The clearance between the valve spool and the spool bore of the housing assembly is important. Because of this, the valve spool and the housing assembly make up a selective assembly (the valve spool is selected to m atch the spool bore). TR U C K S U P P ■ O V E R H A U L 5-4 BRAKES (T y p ic a l) 4. Inspect the input rod and piston assembly for corrosion, nicks, scoring or excessive wear. If the piston is damaged, the input rod and piston assembly should be replaced. 5. Inspect the piston bore in the booster housing for corrosion, nicks, scoring or other damage. If the bore is damaged, the entire booster must be replaced as an assembly. Assembly CAUTION: Be sure to keep parts clean until reassembly. Re-wash at reassembly if there is any occasion to doubt cleanliness - such as parts dropped or left exposed for eight hours or longer. Lubricate all seals and metal friction points with power steering fluid. Whenever the booster is disassembled, all seals, tube inserts and bracket nut should be replaced. All of these parts are included in a seal kit. I f any of the accumulator valve components are damaged or lost, replace all valve components (all are included in charging valve kit). 1. Position a NEW tube seat in each booster port and screw a spare tube nut in each port to press the seat down into the port. Do not tighten the tube nuts in the port as this may deface the seats. 2. Remove the spare tube nuts and check for aluminum chips in the ports. Be sure that any foreign m atter is removed. 3. Coat the piston bore and the piston seal with clean power steering fluid, and assemble the NEW seal in the bore. The lip of the seal must be toward the rear (away from the m aster cylinder m ounting flange). Be sure the seal is fully seated in the housing. 4. Lubricate the input rod end, NEW input rod seals and Seal Installer Tool J-24553 with clean power steering fluid. Slide the seals on the tool with the lip of the cups toward the open end of the tool (fig. 6). 5. Slide the tool over the input rod end and down to the second groove; then slide the forward seal off the tool and into the groove. Assemble the other seal in the first groove. Be sure that both seals are fully seated. 6. Lubricate the piston and Piston Installing Tool J-24551 with clean power steering fluid. Insert the large end of the tool into the piston (fig. 7), and slide the tool and piston into the piston bore and through the piston seal. 7. Assemble the NEW "O" ring onto the NEW accum ulator check valve, and dip the assembly in clean power steering fluid. Insert the check valve into the accum ulator valve recess in the housing flange. Fig. 6 —1nsta I ling In p u t Rod S eals 8. Assemble the new ball and spacer in the same recess. TRUC K SUP P ■ O V E R H A U L BRAKES 5-5 Fig. 8 --ln s ta llin g M o u n tin g B ra c k e t N u t (T yp ical) 9. Assemble the NEW "O" ring onto the charging valve plunger seat and insert the plunger into the seat. Dip the assembly in clean power steering fluid, and insert it into the charging valve recess. 10. Dip the spool assembly in clean power steering fluid, and insert the assembly into the spool bore in the housing. Be sure that the pivot pins on the upper end of the input rod lever assembly are engaged in the groove in the sleeve. Remove Tool J-24551 from the piston assembly. 11. Position a NEW housing seal in the groove in the housing cover. Then join the booster housing and cover and secure with five screws. Tighten the screws to 18-26 ft. lbs. using Special Socket J-25085. CAUTION: See "Caution "on Page 1 o f this section. 12. Assemble a NEW "O" ring seal on the spool plug. Insert the spool spring and the spool plug in the forward end of the spool bore. Press in on plug and assemble the plug snap ring in the groove in the bore. 13. Position the m ounting bracket on the booster. The tab on the inside diam eter of the large hole in the bracket should fit into a slot in the threaded portion of the booster hub. 14. Install the NEW bracket nut with the staking groove outw ard on the threaded hub of the booster. Using Tool J-24554 and a torque wrench (fig. 8), tighten the nut to 95-120 ft. lbs. CAUTION: See "Caution " on Page 1 o f this section. 15. Use a ham m er and a small punch inserted into the staking groove of the nut, at the slot in the booster hub (fig. 9), to stake the nut in place. Be sure that the outer thread of the nut is upset. 16. Assemble a NEW boot (if used) on the pedal rod. Then assemble a NEW grommet in the groove near the end of the pedal rod. 17. Moisten the grommet with water (to ease assembly), and insert the grom m et end of the pedal rod into the input rod end of the booster housing. Push on the end of the pedal rod to seat the grommet in the groove inside the housing. NOTE: W hen the grommet is fully seated, the pedal rod will rotate freely with no binding. 18. Slide the boot on the pedal rod and assemble the large end of the boot onto the hub of the power section. T R U C K SUP P - O V E R H A U L 5-6 BRAKES SPECIAL TOOLS €D ■ m m m hm m m m u J awp i » in 'i (dltaH H i B fjp ^ r r g r * i | J 14 L 11 I 17 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. J-4880 J-25085 J-21183 J-21524 J-21601 J-22657 J-22647 J-22677 J-22733 J-22805 Snap Ring Pliers Special Socket Height Gauge Power Piston Remover and Installer Power Brake Retainer and Installer Bushing Retainer Socket Height Gauge Power C ylinde r Seal Installer Seal Installer and P rotector Power C ylinder H olding F ixtu re 11. J-22839 12. J-22893 13. J-23101 14. J-23175 15. J-23188 16. J-24551 17. J-24553 18. J-24554 19. J-24569 20. J-9504 F ro n t Plate H olding F ixtu re Booster Separating A dap ter Power Piston H olding Tool C ontrol Valve Installer Secondary Bearing P rotector Piston Installer In p u t Rod Seal Installer Socket Pedal Push Rod Remover Power C ylinde r Spanner Wrench Fig. 1 0 -S p e c ia l To ols TRUC K SUP P - O V E R H A U L S E C T IO N 6 ENGINE REPAIR PROCEDURES CAM SH AFT Inspection W hen checking the camshaft for alignment, using the "V" block method, the dial indicator will indicate the exact am ount the cam shaft is out of true. If it is out more than .001" dial indicator reading, the camshaft should be replaced. REPAIRS Piston Selection Piston-to-bore clearance for all engines is increased by .0010" for 1976. Refer to page 6-35 (fig. 74) in the 1974 Overhaul Manual. T R U C K SUP P - O V E R H A U L - % 1 '" I S E C T IO N 6 M CARBURETOR C O N T E N T S OF T H IS S E C T IO N In tro d u ctio n ............................................................................................ 6M -1 Rochester 1M V.................................................................................... .. 6M-1 Rochester 2G C..................................................................................... 6M-5 Rochester 4M V .................................................................................... .. See Introduction Rochester M 4M C /M 4M E ................................................................. .. 6M-11 Special T o o ls......................................................................................... 6M-20 INTRODUCTION A carburetor is designed to meet the particular requirements of the engine, transmission and vehicle and although they may look alike, they are not always interchangeable. Refer to carburetor part num ber a n d /o r specifications. part of a general overhaul, should be performed (if practical) with the carburetor on the engine. Typical illustrations and procedures are used except where specific illustrations or procedures are necessary to clarify the operation. This section, divided into sub-sections by carburetor model, covers the repair procedures for the various carburetors, assembly and disassembly procedures and internal carburetor adjustment. A lthough illustrations showing bench operations are used, most single operations, when not Refer to 1974 Overhaul Manual for overhaul procedures on the Rochester 4MV carburetor. Refer to Light D uty Truck Service Section for external carburetor adjustm ent procedures. ROCHESTER 1M V CARBURETOR IN D E X Disassembly........................................................................................... ..6M -1 Cleaning and Inspection.......................................................................6M-4 A ssem bly..................................................................................................6M-4 Special T o o ls...........................................................................................6M-20 2. Remove fast idle cam from boss on float bowl by DISASSEMBLY removing attaching screw. Then, remove fast idle cam Air Horn from choke rod and choke rod from upper choke lever Removal (Fig. 2). N ote position of rod and cam for ease in 1. Remove auxiliary vacuum break diaphragm assembly from air horn by removing two attaching screws. Remove auxiliary vacuum break diaphragm plunger from vacuum diaphragm link which is permanently attached to the choke lever. The lever and link assembly can be removed, if desired, during choke valve removal (Fig. 1). * . 7 reassembly. NOTE: U pper choke lever is spun on end of choke shaft and cannot be removed. 3. Remove six air horn to bowl attaching screws and lockwashers (three long and three short screws). ' TRUC K S U P P - O V E R H A U L 6M -2 C ARBURETOR Disassembly 1. If desired, the choke valve and choke shaft can be removed from air horn by first removing the therm ostatic coil lever from the end of choke shaft by removing attaching screw. PRESSURE RELIEF VALVE DISC Remove the two choke valve attaching screws; then, remove the choke valve and choke shaft from air horn. The choke valve screws are held in place by Loctite or equivalent so it will be necessary to restake or use Loctite or equivalent during assembly. PRIMARY V A C U U M BREAK D IA P H R A G M 2. No further disassembly of the air horn is necessary. The pressure relief valve disc need not be removed from the top of the air horn for cleaning purposes. Float Bowl (Fig. 3) C H O K E LEVER 1. Remove air horn to float bowl gasket. Gasket is slit next to metering rod lever so that it can be slid over lever for ease in removal. A U XILIARY V A C U U M BREAK D IA P H R A G M 2. Remove float assembly from float bowl by lifting upward on float hinge pin. Remove hinge pin from float arm (Fig. 4). F ig . 1 - A ir H o rn A s s e m b ly 3. Remove float needle from seat. 4. Remove prim ary vacuum break diaphragm unit from the air horn casting. Then, remove the vacuum break hose assembly and link from slotted diaphragm plunger stem. 5. Remove air horn by lifting straight up, invert and place on clean bench. A ir horn to float bowl gasket can remain on bowl for removal later. CHOICE SHAFT AN D LEVER ASSEMBLY AUXILIARY CHOKE VACUUM BREAK DIAPHRAGM 4. Disconnect accelerator pum p and power piston actuator lever from end of throttle shaft by removing lever attaching screw (Fig. 4). 5. Hold down on power piston while removing lever. Power piston spring and metering rod assembly may now be removed from float bowl (Fig. 4). 6. Remove lower end of power piston link from actuator lever by rotating until tang on rod slides out of notch PUMP LEVER PRIMARY CHOKE VACUUM BREAK DIAPHRAGM CHOKE ROD FUEL FILTER PUMP A N D ----METER IN G ROD A C T U A T IN G LEVER IDLE STOP SOLENOID THROTTLE LEVER Fig. 2 - 1 M V C a r b u r e t o r IDLE MIXTURE SCREW A N D LIMITER CAP Fig. 3 - F l o a t B o w l A s s e m b ly TR U C K S U P P - O V E R H A U L C AR BURETOR 6M -3 ACCELER ATO R PUM P P LUN G ER IDLE M A IN W ELL TU B E BLEED H IN G E P IN POW ER P IS T O N FLO A T M E T E R IN G ROD PUMP D IS C H A R G E S P R IN G Fig. 4 - F lo a t a n d A c c e le r a to r P u m p in lever. F ig . 5 - R e m o v in g P u m p D is c h a rg e S p rin g 2. No further disassembly of the throttle body is necessary 7. Remove actuator lever from lower end of accelerator pump link in same manner. unless the idle mixture needle is damaged or the idle 8. Push down on accelerator pum p and remove actuator link by rotating until tang on rod is aligned with slot on pum p plunger lever. Remove the link. mixture needle, cut the tang from the plastic limiter cap. 9. Remove pump assembly from float bowl. readjusted. 10. Remove pump return spring and power piston spring from float bowl. 11. Remove "T" guide and pump discharge spring using needle nose pliers. channels need cleaning. If necessary to remove the idle Do not install a replacement cap as a bare mixture screw is sufficient to indicate that the mixture has been NOTE: Due to the close tolerance fit of the throttle valve in the bore of the throttle body, do not remove the throttle valve or shaft. 12. Pum p discharge ball and idle tube can be removed at the same time by inverting the bowl. 13. Remove main metering jet from bottom of fuel bowl. 14. Remove float needle seat and gasket. TH R O TTLE 15. Remove two screws from idle compensator cover (A.T. only). Then remove cover, hot idle com pensator and seal from recess in bowl. 16. The idle stop solenoid can be removed at this time, if desired. TH R O TTLE V A LV E 17. Remove the fuel inlet nut and gasket; then, remove the filter and relief spring. No further disassembly of the float bowl is required. T h ro ttle Body (Fig. 6) 1. Invert carburetor bowl on bench and remove two throttle body to bowl attaching screws and lockwashers. Throttle body and insulator gasket may now be removed. SPAR K PORTS Fig. 6 - T h r o t t l e B od y A s se m b ly TR U C K S UPP - O V E R H A U L 6M -4 C AR BURETOR CLEANING AND INSPECTION The carburetor should be cleaned in a cold immersion type cleaner. 1. Thoroughly clean carburetor castings and metal parts in an approved carburetor cleaner such as Carbon X (X-55) or its equivalent. Rubber and plastic parts should not be immersed in carburetor cleaner. However, the air horn which has the plastic relief valve will withstand normal cleaning in carburetor cleaner. 2. Blow out all passages in castings with compressed air. Do not pass drills through jets or passages. 3. Examine float needle and seat assembly for wear. Install a new factory m atched set if worn. 4. Inspect upper and lower casting sealing surfaces for damage. 5. Inspect holes in levers for excessive wear or out of round condition. If levers are worn they should be replaced. 6. Examine fast idle cam for excessive wear or damage. 7. Check throttle and choke levers and valves for binds and other damage. 8. Check all springs for distortion or loss in tension; replace as necessary. NOTE: W hen carburetor has been disassembled, new gaskets and filter m ust be used. ASSEMBLY T h ro ttle Body 1. Invert float bowl and install new throttle body to bowl insulator gasket. 2. Install throttle body on bowl gasket so that all holes in throttle body are aligned with holes in gasket. 3. Install two throttle body to bowl attaching screws and lockwashers. Tighten even and securely to 15 ft. lbs. Float Bowl 11. Install power piston return spring into piston cavity in the bowl. 12. Install power piston actuating rod (right angle end) into slot in the power piston. 13. Install piston, metering rod and actuating rod assembly into the float bowl. End of actuating rod must enter hole in bowl. Locate metering rod into jet orifice. 14. Install pum p plunger assembly into pump well with actuating lever protruding through bottom of bowl casting. Push downward on pum p fever and install pump assembly drive link into slot in lower end of shaft. Ends of drive link point inboard tow ard carburetor bore. Tang on upper end of link retains link to pump shaft. (Fig. 4). 15. Install lower end of pump link into actuator lever which fits on throttle shaft. 16. Install curved power piston actuator link into throttle actuator lever. End protrudes outward away from throttle bore and has tang which retains link to lever. 17. Before fastening power piston and pum p actuator lever to end of throttle shaft, hold power piston assembly down and slide upper end of curved power piston actuator link into lower end of power piston actuator rod. 18. Install actuating lever on end of throttle shaft by aligning flats on lever with flats on shaft. Install lever retaining screw and tighten securely. 19. Install float needle valve into needle seat. 20. Install float hinge pin into float arm. Then install float and hinge pin into float bowl. Float Level Adjustm ent (Fig. 7) 1. Hold float retaining pin firmly in place and push down on float arm at outer end against top of float needle. 2. Use adjustable "T" scale and measure distance from top of float at index point on toe to float bowl gasket surface (gasket removed). 1. Install idle stop solenoid, if removed. 2. (A.T. only) Install seal into recess in idle compensator cavity in float bowl, then install compensator assembly. 3. Install idle com pensator cover, retaining with two attaching screws. Tighten securely. 4. Install main metering jet into bottom of fuel bowl. Tighten securely. 5. Install needle seat and gasket. 6. Install idle tube flush with bowl casting. 7. Install pump ball, spring and "T" into pump discharge hole. 8. Push down on pum p discharge "T" until flush with bowl casting. (Fig. 4). 9. Install fuel filter spring, filter, inlet nut and gasket. 10. Install accelerator pum p return spring. F ig . 7 - F lo a t L e ve l A d ju s tm e n t T R U C K SUP P - O V E R H A U L C A R BU RE TO R 3. Bend float pontoon up or down at float arm junction to adjust. Metering Rod Adjustment (Fig. 8) 2. To check adjustment, back out idle stop solenoid and rotate fast idle cam so that fast idle cam follower is not contacting steps on cam. 3. W ith throttle valve completely closed, apply pressure to top of power piston and hold piston down against its stop. 4. Holding downward pressure on power piston, swing metering rod holder over flat surface of bowl casting next to carburetor bore. 5. Insert gauge between bowl casting and lower surface of metering rod holder. Gauge should have a slide fit between both surfaces, as shown. © F LO A T BOWL SURFACE (GASKET R EM OVED) R BACK O U T ID LE SPEED SCREW HO LD TH R O T TLE V A L V E C OM PLETELY CLOSED Air Horn 1. Install choke shaft assembly and choke valve into air horn, if removed. Align choke valve, tighten two retaining screws and stake securely or use Loctite or equivalent. 2. Install air horn to float bowl by lowering gently onto float bowl until seated. Install three long and three short air horn to float bowl attaching screws and lockwashers. Tighten screws securely. Install the prim ary choke vacuum break diaphragm assembly under the two short air horn screws next to the therm ostatic coil lever. Connect the choke vacuum break diaphragm link to slotted diaphragm plunger stem and install lever to the end of the choke shaft, using retaining screw. Tighten all screws securely. 4. Assemble choke rod into the slot in the upper choke lever. End of rod points away from air horn casting when installed properly. PLUG GAUGE © 8. Install air horn gasket on float bowl by carefully sliding slit portion of gasket over metering rod holder. Then align gasket with dowels provided on top of bowl casting and press gasket firmly in place. 3. Install the choke vacuum break diaphragm hose to the diaphragm on air horn and tube on float bowl. BENDING TOOL H O LD POWER PISTON D O W N ' 6. To adjust, carefully bend metering rod holder up or down. 7. After adjustment, install metering rod and spring assembly. Install rod in jet, then install in hanger. 1. Open throttle valve, slide metering rod out of holder and remove from main metering jet. ® 6 M -5 5. Install iow er end of choke rod into fast idle cam. Steps on fast idle cam should face fast idle tang on throttle lever. Install fast idle cam to, boss on float bowl with attaching screw. Tighten securely. 6. Install auxiliary vacuum break diaphragm link attached to the choke lever to slot in the diaphragm plunger stem. Then, install the auxiliary vacuum break diaphragm unit to air horn using two attaching screws. Tighten securely. Fig. 8 - M e te r in g Rod A d ju s tm e n t ROCHESTER 2GC INDEX G eneral................................................................................................... ..6M-6 Disassembly........................................................................................... ..6M-6 Cleaning and Inspection.......................................................................6M-8 A ssem bly..................................................................................................6M-9 Special T o o ls...........................................................................................6M-20 TRUC K SUP P - O V E R H A U L 6M -6 C AR BU RETOR GENERAL Flooding, stumble on acceleration and other performance complaints are, in m any instances, caused by the presence of dirt, water or other foreign m aterial in the carburetor. To aid in diagnosing the cause of complaint, the carburetor should be carefully removed from the engine without draining fuel from the bowl. The contents of the fuel may then be examined for dirt or water problems as the carburetor is disassembled. The following is a step-by-step sequence by which the model 2GC carburetor (Fig. 1C) may be completely disassembled and reassembled. Adjustments may be made and various parts of the carburetor may be serviced without completely disassembling the entire unit. Refer to service section for external adjustments. SPR IN G LIP AIR H O R N S' ACCELERATO R PU M P ROD FUEL INLET THROTTLE LEVER Fig. 2 C -R e m o v in g P um p Rod S p rin g C lip of the choke rod cannot be removed from the choke lever until after the air horn has been removed from the float bowl. 7. Remove eight air horn attaching screws and lockwashers, then lift air horn from float bowl (Fig. 3C). 8. Place air horn on flat surface. Remove float hinge pin and lift float from air horn. Float needle, and pull clip (if used), may now be removed from float arm (Fig. 4C). C H O K E HEAT INLET PURG E TUBE 9. Remove float needle seat and gasket with a wide blade screwdriver. Fig. 1 C -F to ch e ster 2 G C C a rb u re to r DISASSEMBLY 10. Remove power piston by depressing stem and allowing it to snap free. Use care not to bend the power piston stem. Air Horn 1. Remove fuel inlet filter nut and gasket, and remove filter and spring. 2. Disconnect lower end of pump rod from throttle lever by removing spring clip (Fig. 2C). 3. Remove upper end of pump rod from pump lever by rotating rod out of hole in lever. 4. Remove the vacuum break diaphragm hose from tube on throttle body and tube on vacuum break diaphragm unit. Then remove the vacuum break diaphragm assembly from air horn by removing two attaching screws. Remove diaphragm and link assembly from lever on end of choke shaft. 5. Remove vacuum break lever from end of choke shaft by removing retaining screw in end of shaft. Then, remove the interm ediate choke rod from the vacuum break lever and from the lever on the therm ostatic coil housing. 6. Remove fast idle cam attaching screw from side of float bowl. Remove fast idle cam from end of choke rod by rotating rod out of hole in fast idle cam. The upper end Fig. 3 C - R e m o v i n g A ir Horn T R U C K SUP P • O V E R H A U L C AR BU RETOR 6 M -7 INNER PUMP LEVER ACCELERATING PUMP ASSEMBLY SCREW (B) M A IN M ETERING JET FLOAT UMP PLUNGER RETURN SPR IN G PUMP INLET CHOKE VALVE FLOAT HINGE PIN ruw cR VALVE NEEDLE AND SEAT Fig . 5 C - F lo a t B o w l F ig . 4 C - A ir H o rn 11. Remove the pump plunger assembly and inner pump lever from pump shaft by loosening set screw on inner lever. To remove the pum p plunger stem from the inner pump lever it will be necessary to break off the swedged or flattened end of the pump plunger stem. This should not be done unless pump assembly replacement is necessary, such as during overhaul. The service pump assembly uses a grooved pump plunger stem and retaining clip. A fter removing the inner pum p lever and pum p assembly, remove the outer pump lever and shaft assembly from air horn. Remove the plastic washer on pump plunger shaft. 12. Remove air horn gasket from air horn. 13. Remove fuel inlet baffle next to needle seat. 14. Remove two choke valve attaching screws, then remove choke valve. Care should be taken when removing attaching screws so that the choke shaft will not be bent. It may be necessary to file off staked ends on choke valve screws before removing. ADJUSTABLE PART THROTTLE FUEL INLET 5. Invert carburetor and remove three large throttle body to bowl attaching screws and lockwashers. Throttle body and gasket may now be removed. Throttle Body 1. Remove the three choke cover attaching screws and retainers, then remove therm ostatic coil and cover assembly and gasket from choke housing (Fig. 7C). CAUTION: D o n o t remove cup baffle from beneath therm ostatic co il cover because c o il distortion may result. 2. Remove baffle plate from inside choke housing (Fig. 8C). 3. Remove the two choke housing attaching screws from inside choke housing, then remove choke housing and gasket from throttle body casting. 15. Remove choke valve shaft from air horn. 16. Remove the fast idle cam rod and lever from the choke shaft. PLASTIC M A IN WELL INSERT Float Bowl 1. Remove pump plunger return spring from inside pump well. Then remove aluminum check ball from bottom of pump well by inverting bowl (Fig. 5C). SPRING RETAINER 2. Remove main metering jets, power valve and gasket from inside float bowl. 3. Remove three screws holding venturi cluster to float bowl and remove cluster and gasket. Then remove the plastic main well inserts in the main well cavity. 4. Using a pair of long nosed pliers, remove pump discharge spring retainer (Fig. 6C). Then, spring and check ball may also be removed from discharge passage. Fig. 6 C - R e m o v i n g S p rin g R et ain er TR U C K S UPP - O V E R H A U L 6M -8 C AR BU RETOR O FF-ID LE D IS C H A R G E PORT !DLE M'XTURE CHOKE CO VER SC R EW (3 ) E H O U S IN G SPEED SCR EW CHOKE VACUUM TUBE R ETA IN ER (3) FIXED IDLE A IR BLEED INTERM EDIATE C H O K E LEVER F ig . 7 C - T h r o ttle B o d y 4. Remove screw from end of intermediate choke shaft and remove intermediate choke lever from shaft (Fig. 9C). Remove inner choke coil lever and shaft assem blyfrom choke housing. Remove rubber dust seal from inside choke housing. 5. The idle m ixture needles have been adjusted and set at the factory and capped, to prevent excessive adjustment in the field. However, the carburetor has a limited idle mixture adjustment. If it is necessary to remove the idle mixture needles for cleaning purposes or if they are defective, the following procedure should be used: Using a pair of side cutter pliers, clip off the limit tang on the limiter cap. Then unscrew the idle m ixture screw and spring from throttle body. If new idle mixture needles are installed, no plastic limiter caps are required. If the original idle m ixture needles had to be removed, install the idle mixture needle and springs into throttle body as described under Assembly. No further disassembly of the throttle body is necessary. F ig . 9 C - C h o k e H o u s in g CAUTION: N o attem pt should be made to remove the th ro ttle valves o r shaft as i t may be impossible to reassemble the th ro ttle valves correctly in relation to the id le discharge orifices. CLEANING AND INSPECTION Dirt, gum, water or carbon contam ination in or on exterior moving parts of the carburetor are often responsible for unsatisfactory performance. For this reason, efficient carburetion depends upon careful cleaning and inspection while servicing. 1. Thoroughly clean carburetor casting and metal parts in an approved carburetor cleaning solution. (Example: X-55 or equivalent). CAUTION: A n y rubber parts, plastic parts, diaphragm assemblies, pum p plungers, should not be immersed in carburetor cleaner. 2. Blow out all passages in castings dry with compressed air and blow off all parts until they are dry. CAUTION: D o n o t pass d rills o r wires through calibratedjets o r passages as they m ay enlarge orifices and seriously affect carburetor calibration. 3. Check all parts for wear. If wear is noted, defective parts must be replaced. N ote especially the following: CH O KE H O U S IN G C HO KE COVER b. Check float lip for wear and float for damage. Repair or replace as necessary. SCREW BAFFLE PLATE Fig. 8 C - C a r b u r e t o r C h o k e a. Check float needle and seat for wear. If wear is noted, the assembly must be replaced. c. Visually check throttle and choke shaft bores in throttle body and cover castings for wear and out of round. Repair or replace as necessary. d. Inspect idle adjusting needles (if removed) for burrs or ridges, or being bent. Such a condition requires replacement. TR U C K S U P P - O V E R H A U L C AR BURETOR 6M -9 e. Inspect fast idle cam. If wear is noted on steps of cam, it should be replaced as it may upset engine idle speed during the warm-up period. 3. Drop small alum inum inlet check ball into hole in pum p well, install pump return spring, pressing with finger to center in pump well. f. Inspect the pump plunger cup and expander spring. Replace plunger if cup or spring is damaged or distorted. 4. D rop steel pum p discharge ball into pump discharge hole located beneath the venturi cluster. Ball is 3/16" diameter (do not confuse with aluminum inlet ball). Install pump discharge ball spring and retainer. g. Inspect power piston and spring for burrs or being bent. Replace as necessary. 4. Check filters for dirt or lint. Replace as necessary. 5. Inspect venturi cluster casting. If any parts in casting are loose or damaged, the cluster assembly must be replaced. 6. Use new gaskets in reassembly. ASSEMBLY Throttle Body 1. Install idle speed screw and spring assembly in throttle body if removed (Fig. 7C). 2. If it was necessary to remove the idle mixture needles, install the idle m ixture needles and springs into the throttle body until finger tight and seated. Back out screws four turns as a preliminary idle adjustment. 3. Install new rubber dust seal into cavity inside choke housing (Fig. 9C). Lip on seal faces towards carburetor after the housing is installed. 4. Install inner choke coil lever and shaft assembly into choke housing. 5. W ith the choke coil lever and shaft assembly installed into housing, install the interm ediate choke lever on flats of intermediate choke shaft and retain with screw. Tighten securely. 6. Install new choke housing to carburetor gasket. 7. Position choke housing on throttle body and retain with two attaching screws. Tighten securely (Fig. 8C). 8. Before installing the choke cover coil and baffle plate assembly, refer to interm ediate choke rod adjustment (Service) to adjust interm ediate choke rod so that with the choke valve closed, the lever inside the choke housing lines up with gauge. 9. Install choke therm ostatic coil and cover assembly with new gaskets and end of coil below plastic tang on the inner choke housing lever. Refer to autom atic choke coil adjustm ent (Service) to index cover. Install three choke therm ostatic coil retainers and screws. Tighten securely (Fig. 1C). 10. Place a new gasket on the bottom of the float bowl with holes in gasket aligned with holes in casting, then position the throttle body on gasket and install the three attaching screws. Tighten screws evenly and securely. Float Bowl 1. Install two main metering jets into bottom of float bowl (Fig. 5C). 2. Install power valve and gasket into bottom of float bowl using slotted screwdriver. Tighten securely. 5. Install plastic main well inserts into the main fuel wells located beneath the venturi cluster and make sure they are seated in recesses provided (Fig. 6C). Then install venturi cluster and gasket, tighten three screws evenly and securely. M ake certain center screw is fitted with a gasket to prevent pum p discharge leakage. Air Horn (Fig. 4C) 1. Install the upper choke rod lever and collar assembly on to choke shaft. Then install the choke shaft assembly into the air horn from the throttle lever side. Then install the choke valve onto the choke shaft with the letters "RP" or part num ber facing upward. Install the choke valve attaching screws. Center the choke valve before tightening choke valve screws. Tighten choke valve screws and stake lightly in place. Check choke and shaft for freedom of movement. 2. If removed, install the outer pump shaft and lever assembly into air horn casting. Make sure the plastic washer is in place before installing the outer pump shaft and lever assembly. 3. Instair the pum p plunger to the inner lever and retain with clip provided in the repair kit. End of pump plunger shaft should point inward towards center of carburetor when installed correctly. Then install inner pump lever onto the pum p shaft and tighten set screws securely. 4. Position the float needle seat gasket on the needle seat and install seat in the air horn. Tighten securely. 5. Install the power piston assembly into the air horn casting and lightly stake the retaining washer to casting. M ake sure the piston travels up and down freely and is not bent. < 6. Install fuel inlet baffle next to needle seat. Make sure baffle is seated in grooves in air horn casting. 7. Install air horn gasket onto air horn casting. 8. Install float needle into needle seat. Then install float assembly on air horn and insert hinge pin. Check float action and for free movement of needle in the seat. 9. Check float level and drop adjustments. Float Level Adjustment With air horn inverted, gasket in place and needle seated measure distance from lip at toe of float to air horn gasket. Adjust float to specifications by bending the float arm at point shown (Fig. 10C). TRUC K SUP P - O V E R H A U L 6M -10 C ARBURETOR (3 )V IS U A L L Y C H EC K FO R FL O A T A LIG N M E N T Float Drop Adjustment W ith air horn right side up so that float can hang free, measure distance from lip at toe of float air horn gasket. Adjust float drop to specifications by bending tang (Fig. 11C) at the rear of the float hanger. 10. Install choke rod in upper choke lever and collar assembly rotating rod until squirt in end of rod aligns with slot in lever. Air Horn to Float Bowl 1. Place the air horn assembly on bowl, making certain that the accelerator pum p plunger is correctly positioned into pump well and will move freely. 2. Install lockwashers and tighten eight air horn attaching screws evenly and securely (Fig. 12C). F ig . 1 2 C - A ir H o rn T ig h te n in g S e q u e n c e 3. Install filter pressure relief spring into air horn casting, then install fuel inlet filter (gasket end facing nut) and fuel inlet nut and gasket. Tighten nut to 25 ft. lbs. 4. Install fast idle cam to lower end of choke rod (part number or identification faces outward on fast idle cam assembly). Then install the fast idle cam to float bowl retaining with the fast idle cam attaching screw. Tighten securely. Move linkage up and down to make sure that the cam will fall freely. 5. Install pum p rod into upper pum p lever by rotating offset end into hole in lever and install lower end of pump rod to throttle lever and retain with a spring clip (Fig. 2C). 6. Install vacuum break diaphragm assembly onto air horn with two attaching screws. Tighten securely. 7. Install lower end of intermediate choke rod into intermediate choke lever on choke housing and connect upper end of rod to vacuum break lever. Install vacuum break diaphragm rod into stem of vacuum break diaphragm and vacuum break lever. 8. Install the vacuum break lever onto end of choke shaft making sure that the lever fits over flats on shaft. Install attaching screw and tighten securely. 9. Connect vacuum break hose to diaphragm unit and vacuum tube on throttle body. After complete carburetor assembly, check and re-set (if necessary) all choke adjustments and pum p rod adjustments. T R U C K SUP P - O V E R H A U L C AR BU RETOR 6M -11 M 4 M C /M 4 M E QUADRAJET CARBURETOR IN D E X G eneral................................................................................................... .. 6M-11 Disassem bly........................................................................................... .. 6M -11 Cleaning and Inspection....................................................................... 6M-16 A ssem bly...................................................................................................6M-17 Special T ools............................................................................................6M-20 GENERAL Before performing any service on the carburetor, it is essential that the carburetor be placed on a holding fixture such as Tool J-8328. W ithout the use of the holding fixture, it is possible to bend or nick throttle valves (Fig. 1MQ and 1MQ-A). DISASSEMBLY Throttle Lever Actuator Remove the throttle lever actuator vacuum unit and bracket assembly used on some truck applications. CAUTION: The th ro ttle lever actuator should not be immersed in any type o f carburetor cleaner and should always be removed before complete carburetor overhaul. Fig. 1 M Q - M 4 M C Q u a d r a j e t C a r b u r e t o r Air Horn 1. Remove upper choke lever from the end of choke shaft by removing retaining screw (Fig. 2MQ). Then rotate upper choke lever to remove choke rod from slot in lever. 2. Remove choke rod from lower lever inside the float bowl casting by holding lower lever outward with small screwdriver and twisting rod counterclockwise. 3. Remove secondary metering rods by removing the small screw in the top of the metering rod hanger. Lift upward on metering rod hanger until the secondary metering rods are completely out of the air horn. Metering rods may be disassembled from the hanger by rotating ends out of the holes in the end of the hanger. (Fig. 3MQ). 4. Using special tool J-25322, drive small roll pin (pump lever pivot pin) inward just enough until pump lever can be removed from air horn. Then remove pump lever from pump rod (Fig. 4MQ). Fig. 1 M Q - A - - M 4 M E Q u a d r a j e t C a r b u re t o r TR U C K SUP P - O V E R H A U L 6M -12 C AR BU RETOR P U M P LEVER Fig . 2 M Q - R e m o v in g U p p e r C h o k e L e v e r F ig . 4 M Q - R e m o v in g P u m p L e ve r CAUTION: Use care in rem oving sm all ro ll p in to CAUTION: When rem oving a ir horn from floa t prevent damage to pum p lever casting bosses in a ir horn. bowl, use care to prevent bending the sm all tubes protruding from the a ir horn. These tubes are perm anently pressed in to the a ir horn casting. D O N O T R EM OVE. 5. Remove nine air horn to bowl attaching screws; two attaching screws are located next to the venturi. (Two long screws, five short screws, and two countersunk screws). (Fig. 5MQ). 6. Remove air horn from float bowl by lifting straight up. The air horn gasket should remain on the float bowl for removal later (Fig. 6MQ). Air Horn Disassembly Remove front vacuum break bracket attaching screws. The diaphragm assembly may now be removed from the air valve dashpot rod and the dashpot rod from the air valve lever (Fig. 7MQ). CAUTION: D o not place vacuum break assembly in carburetor cleaner. Further disassembly of the air horn is not required for cleaning purposes. If part replacement is required, proceed as follows: Fig. 3 M Q - R e m o v i n g S e c o n d a r y M e te r in g Rods Fig. 5 M Q - R e m o v i n g A ir Horn S crew s TR U C K S U P P - O V E R H A U L C AR BU RETOR 6M -13 Float Bowl 1. Remove air horn gasket by lifting out of dowel locating pins and lifting tab of gasket from beneath the power piston hanger, being careful not to distort springs holding the main metering rods (Fig. 8MQ). 2. Remove pump plunger from pump well. 3. Remove pum p return spring from pump well. 4. Remove power piston and metering rods by depressing piston stem and allowing it to snap free (Fig. 9MQ). The power piston can be easily removed by pressing the piston down and releasing it with a snap. This will cause the power piston spring to snap the piston up against the retainer. This procedure may have to be repeated several times. CAUTION: D o n o t remove pow er piston by using pliers on m etering ro d hanger. Remove the power piston spring from the well. F ig . 6 M Q -R e m o v in g A ir H o rn 1. Remove staking on two choke valve attaching screws, then remove choke valve and shaft from air horn. 2. A ir valves and air valve shaft should not be removed. 3. If it is necessary to replace the air valve closing spring or center plastic eccentric cam, a repair kit is available. CAUTION: The A .P .T. metering rod adjustment screw is pre-set a t the factory and no attem pt should be made to change this adjustment in the field. I f flo a t bowl replacement is required during service, the new bowl assembly w ill be supplied w ith an A.P.T. m etering ro d screw which w ill be pre-set as required. 5. Remove metering rods from power piston by disconnecting tension spring from top of each rod, then rotate rod to remove from hanger (Fig. 10MQ). CAUTION: Use care when disassembling rods to prevent distortion o f tension spring a n d /o r metering rods. Note carefully position o f tension spring fo r la te r reassembly. Instructions for assembly are included in the repair kit. Fig. 7 M Q - R e m o v i n g Fron t V a c u u m B re ak Fig. 8 M Q - R e m o v i n g A ir Horn G a s k e t and Pum p P lunge r TRUC K SUP P - O V E R H A U L 6M -14 C A R BU RE TO R R E T A IN IN G Fig. 9 M Q - R e m o v in g P o w e r P is to n a n d M e te rin g R ods 6. Remove plastic filler block over float valve. 7. Remove float assembly and float needle by pulling up on retaining pin. Remove float needle seat and gasket. (Fig. 11MQ). 8. Remove aneroid cavity insert from float bowl (Fig. 12MQ). 9. Remove prim ary main metering jets (Fig. 13MQ). NOTE: No attem pt should be made to remove the secondary m etering orifice plates. These jets are fixed and, if damaged, bowl replacement is required. 10. Remove pum p discharge check ball retainer and check ball. F ig . 1 1 M Q - F lo a t A s s e m b ly M 4 M E M o d e l W ith R e a r V a c u u m B r e a k 11. Remove hose from rear vacuum break control assembly. Remove two screws from rear vacuum break bracket and rotate the assembly to remove vacuum break rod from slot in plunger head (Fig. 14MQ). CAUTION: Do not place vacuum break assembly in carburetor cleaner. R E TA IN IN G SPRING METERING ROD POWER PISTON POWER PISTON SPRING Fig. 1 0 M Q - P o w e r Piston an d M e t e r in g Rods Fig. 1 2 M Q - R e m o v i n g A n e r o id C av ity Insert TRUC K SUP P • O V E R H A U L C AR BU RE TO R PUMP DISCHARGE 6M -15 On M 4M C hot air choke model, it is not necessary to remove baffle plate from beneath the therm ostatic coil. Distortion of the therm ostatic coil may result if forced off the center retaining post on the choke cover. 2. Remove choke housing assembly from float bowl by removing retaining screw and washer inside the choke housing (Fig. 15MQ). The complete choke assembly can be removed from the float bowl by sliding outward. 3. Remove secondary throttle valve lock-out lever from float bowl. (Fig. 16MQ). 4. Remove lower choke lever from inside float bowl cavity by inverting bowl. 5. Remove plastic tube seal from choke housing (Fig. 16MQ). CAUTION: Plastic tube seal should not be immersed in carburetor cleaner. Fig. 1 3 M Q - F lo a t B o w l J e ts 12. Remove vacuum break rod by holding down on fast idle cam (hot idle position); move end of vacuum break rod away from float bowl; then disengage rod from hole in intermediate choke lever. Choke 1. Remove three attaching screws and retainers from choke cover and coil assembly. Then pull straight outw ard and remove cover and coil assembly from choke housing. Remove choke cover gasket, if used. 6. To disassemble intermediate choke shaft from choke housing, remove coil lever retaining screw at end of shaft inside the choke housing (Fig. 15MQ). Then remove therm ostatic coil lever from flats on intermediate choke shaft. Remove intermediate choke shaft from the choke housing by sliding outward. The fast idle cam can now be removed from the intermediate choke shaft (Fig. 16MQ). CAUTION: Remove the cup seal from inside choke housing shaft hole if the housing is to be immersed in carburetor cleaner. Also, remove the cup seal from the floqt bowl plastic insert for bowl cleaning purposes. DO NOT ATTEMPT TO REMOVE PLASTIC INSERT. CHOKE H O U S IN G Fig. 1 4 M Q - R e a r V a c u u m B re ak A T T A C H IN G SCREW Fig. 1 5 M Q - R e m o v i n g C h o k e Housing TRUC K S U P P ■ O V E R H A U L 6M -16 C AR BU RETOR ATTACHING SCREWS TUBE SEAL REAR VACUUM BREAK LEVER FAST IDLE CAM LOCKOUT PIN SECONDARY LOCK OUT LEVER FAST IDLE CAM FOLLOWER INTERMEDIATE CHOKE SHAFT F ig . 1 8 M Q -R e m o v in g T h r o tt le B o d y F ig . 1 6 M Q - C h o k e H o u s in g A s s e m b ly Float Bowl Disassembly 1. Remove fuel inlet nut, gasket and filter (Fig. 17MQ). 2. Remove secondary air baffle, if replacement is required. 3. Remove pum p well fill slot baffle, if replacement is required. 4. Remove throttle body by removing throttle body to bowl attaching screws (Fig. 18MQ). 5. Remove throttle body to bowl insulator gasket (Fig. 19MQ). Throttle Body Disassembly cap. Do not install a replacement cap as a bare mixture screw is sufficient to indicate that the mixture has been re-adjusted. CLEANING AND INSPECTION 1. Thoroughly clean carburetor castings and metal parts in an approved carburetor cleaner, such as Carbon X(X-55) or its equivalent. CAUTION: The th ro ttle lever actuator, electric choke rubber parts, filte r plastic parts, pum p plunger, and choke vacuum break(s) should not be immersed in carburetor cleaner. However, the th ro ttle valve shafts w ill withstand norm al cleaning in carburetor cleaner. 1. Remove pum p rod from throttle lever. 2. DO N O T REM O V E idle m ixture limiter caps, unless it is necessary to replace the m ixture needles or normal soaking and air pressure fails to clean the idle passages. If the idle mixture needles are removed, refer to Service Section for adjustm ent procedure. If necessary to remove the idle mixture needle, destroy plastic limiter FUEL INLET NUT FILTER SPRING Fig. 1 7 M Q - F u e l Filter Fig. 19 M Q - R e m o v i n g In s u la to r G a s k e t TR U C K SUP P - O V E R H A U L CAR BU RETOR 2. Blow out all passages in castings with compressed air. CAUTION: Do not pass drills through jets or passages. 3. Examine float needle and seat for wear. Replace, if necessary, with new float needle and seat assembly. 4. Inspect upper and lower surfaces of carburetor castings for damage. 5. Inspect holes in levers for excessive wear or out of round conditions. If worn, levers should be replaced. 6. Examine fast idle cam for wear or damage. 7. Check air valve for binding conditions. If air valve is damaged, air horn assembly m ust be replaced. 8. Check all throttle levers and valves for binds or other damage. ASSEMBLY Throttle Body 1. If removed, install idle m ixture needles and springs until seated. Back out the mixture needles 4 turns as a preliminary idle adjustment. Final adjustm ent must be made on the engine using the procedures described under slow idle adjustment. 2. Install lower end of pum p rod in throttle lever by aligning tang on rod with slot in lever. End of rod should point outwards towards throttle lever. Float Bowl Assembly 1. Install new throttle body to bowl gasket over two locating dowels on bowl. 2. Install throttle body making certain throttle body is properly located over dowels on float bowl, then install throttle body to bowl screws and tighten evenly and securely (Fig. 18MQ). 6M -17 properly aligned when both inside and outside levers face towards fuel inlet. Install inside lever retaining screw into end of interm ediate choke shaft. Tighten securely. 6. Using Tool J-23417, install lower choke rod lever into cavity in float bowl. Install plastic tube seal into cavity on choke housing before assembling choke housing to bowl. Install choke housing to bowl sliding intermediate choke shaft into lower choke lever (Fig. 20MQ). NOTE: The interm ediate choke shaft lever and fast idle cam are in correct relation when the tang on lever is beneath the fast idle cam. Do not install choke cover and coil assembly until inside coil lever is adjusted. Refer to Service Section for adjustment procedures. Float Bowl M 4 M E M odel W ith Rear Vacuum Break 1. Holding down on fast idle cam (hot idle position), install end of vacuum break rod in hole in intermediate choke lever. 2. Install end of vacuum break rod in slot in rear vacuum break plunger head. Then install rear vacuum break control and bracket assembly to float bowl using two attaching screws (Fig. 14MQ). Tighten securely. NOTE: Do not attach vacuum break hose until after the vacuum break adjustm ent is complete. Refer to Service Section for adjustm ent procedure. A ll Models 3. If removed, install air baffle in secondary side of float bowl with notches tow ard the top. Top edge of baffle must be flush with bowl casting. 3. Place carburetor on proper holding fixture J-8328. 4. Install fuel inlet filter spring, filter, new gasket and inlet nut and tighten nut to 18 pounds feet (Fig. 17MQ). NOTE: Ribs on closed end of filter element prevent filter from being installed incorrectly unless forced. CAUTION: Tightening beyond specified torque can damage nylon gasket. Choke 1. Install new cup seal into plastic insert on side of float bowl for intermediate choke shaft. Lip on cup seal faces outward. 2. Install secondary throttle valve lock-out lever on boss on float bowl with recess in hole in lever facing inward. 3. Install new cup seal into inside choke housing shaft hole. Lips on seal face inward, towards inside of housing. 4. Install fast idle cam onto the interm ediate choke shaft (steps on fast idle cam face downward) (Fig. 16MQ). 5. Carefully install fast idle cam and interm ediate choke shaft assembly through seal in choke housing; then install therm ostatic coil lever onto flats on intermediate choke shaft. Inside therm ostatic choke coil lever is Fig. 2 0 M Q - l n s t a l l i n g C h o k e Rod Lever TRUC K SUP P - O V E R H A U L 6M -18 C AR BU RETOR 4. If removed, install baffle in pum p well fill slot. 5. Install pump discharge check ball and retainer in passage next to pum p well. Tighten retainer securely. 6. Install prim ary main metering jets (Fig. 13MQ). 7. Install aneroid cavity insert into float bowl. 8. Install new needle seat assembly, with gasket. 9. To make adjustm ent easier, bend float arm upward at notch in arm before assembly. Install needle by sliding float lever under needle pull clip-correct installation of the needle pull clip is to hook the clip over the edge of the float on the float arm facing the float pontoon (Fig. 21MQ). W ith float lever in pull clip, hold float assembly at toe and install retaining pin from aneroid cavity side (ends of retaining pin face the accelerating pump well). CAUTION: D o n o t in s ta ll flo a t needle p u ll clip in to holes in flo a t arm. 10. Adjust float level. Float Level (Fig. 2 2M Q ) a. Hold float retainer firmly in place. b. Push float down lightly against needle. c. W ith adjustable T-scale, gauge from top of float bowl casting (air horn gasket removed) to top of float gauging point 1/16" back from end of float at toe. d. Bend float arm as necessary for proper adjustm ent by pushing on pontoon. Refer to adjustm ent chart for specification. e. Visually check float alignment after adjustment. 11. Install plastic filler block over float needle, pressing downward until properly seated. 12. Install power piston spring in power piston well. If main metering rods were removed from hanger, reinstall making sure tension spring is connected to top of each rod (Fig. 9MQ). Install power piston assembly in well (aligning pin on piston with slot in well) with metering rods properly positioned in metering jets. Press down firmly on plastic power piston retainer to make sure the retainer is seated in recess in bowl and the top is flush with the top of the bowl casting. If necessary, using a drift punch and small hammer, tap retainer lightly in place. 13. Install pum p return spring in pump well. 14. Install air horn gasket by carefully sliding tab of gasket around main metering rods and beneath the power piston hanger. Position gasket over the two dowel pins on the float bowl. 15. Carefully lift one corner of the air horn gasket and install pump plunger in the pum p well by pushing the plunger to the bottom of the well against return spring tension. While holding in this position, align pump plunger stem with hole in gasket and press gasket in place. Air Horn 1. If removed, install choke shaft, choke valve, and two attaching screws. Tighten screws securely and stake lightly in place. 2. Check choke valve for freedom of movement and proper alignment before staking screws in place. Air Horn to Bowl Installation 1. Holding down on air horn gasket at pump plunger location, carefully lower air horn assembly onto float bowl making sure that the bleed tubes, accelerating well tubes, pull-over enrichm ent tubes (if used), and pump plunger stem are positioned properly through the holes in the air horn gasket. CAUTION: D o not force the a ir horn assembly onto the bow l but rather lig h tly low er in place. 2. Install two long air horn screws, five short screws, and two coutersunk screws into prim ary venturi area. All air horn screws must be tightened evenly and securely. See Figure 5MQ for proper tightening sequence. 3. Install vacuum break diaphragm rod into the slot in lever on the end of the air valve shaft. Then install the other end of rod into hole in the front vacuum break diaphragm plunger. Install front vacuum break control and bracket assembly to air horn using two retaining screws through the bracket. Tighten screws securely. NOTE: Do not attach vacuum break hose until vacuum break adjustment is completed. Refer to Service Section for adjustm ent procedure. 4. Connect upper end of pump rod to pump lever by placing rod in specified hole in lever. Align hole in pump lever with hole in air horn casting using J-25322. Using small screwdriver, push pump lever roll pin back TR U C K SUP P • O V E R H A U L C AR BU RETOR 6M -19 G A U G E FR O M TO P OF C A S T IN G TO TOP OF FLO AT — G A U G IN G P O IN T 3 / 1 6 ” BACK F R O M END OF FLO AT A T TOE (SEE INSET) (IN S E T) G A U G IN G P O IN T ( 3 / 1 6 ” BACK FR O M TOE) ( 4 ) R E M O V E FLO AT A N D BEND FLO AT A R M UP OR D O W N TO A D J U S T © P U S H FLOAT D O W N L IG H T L Y A G A IN S T NEEDLE ( 5 ) V IS U A L L Y CHECK FLO AT A L IG N M E N T W AFTER A D J U S T IN G Fig . 2 2 M Q - F lo a t Le ve l A d ju s tm e n t through casting until end of pin is flush with casting bosses in air horn. CAUTION: Use care installing the sm all ro ll p in to prevent damage to pum p lever casting bosses. 5. Install two secondary metering rods into the secondary metering rod hanger (upper end of rods point toward each other). Install secondary metering rod holder, with rods, onto air valve cam follower. Install retaining screw end tighten securely. W ork air valves up and down several times to make sure they are free in all positions. 6. Connect check rod into lower choke lever inside bowl cavity; they install choke rod into slot in upper choke lever and retain the choke lever to the end of the choke shaft with attaching screw. Tighten securely. M ake sure that the flats on the end of the choke shaft align with flats in the choke lever. The front and rear vacuum break units, fast idle cam (choke rod), and inside therm ostatic choke coil lever must be adjusted properly before installing the choke therm ostatic coil and cover assembly and gasket. Refer to the A djustm ent Procedures, in Service Section. 7. After the vacuum break, fast idle cam (choke rod), and inside therm ostatic coil lever are adjusted, the therm ostatic coil and cover, and gasket on hot air choke model, should be installed and the cover assembly rotated until the choke valve just closes. On all models (except 454 V8), tang on therm ostatic coil must be installed in slot in inside choke coil lever pick-up arm. On M 4M E electric choke model, coil tang contacts bottom side of inside choke coil lever pick-up arm. CAUTION: On M 4M E electric choke model, do not in s ta ll a choke cover gasket between the electric choke assembly and the choke housing. Align index point on cover with specified m ark on housing as shown on adjustment chart. Install three choke cover retainers and screws and tighten securely. 8. If used, position and retain throttle lever actuator. TRUCK SUPP - O VER H A U L 6M -20 C ARBURETOR SPECIAL TOOLS J-22973 THER-MAC THERMOMETOR J-8328 CARBURETOR HOLDING TOOL (Set of 4) J-9789-01 UNIVERSAL CARBURETOR GAUGE SET J-25322 PUMP LEVER PIN DRIVE PUNCH C—--- J-23417 CHOKE LEVER INSTALLING TOOL J-5197 BENDING TOOL Fig. 1S T- -S pe cial To ols TRUC K S U P P - O V E R H A U L S E C T IO N 6 Y ENGINE ELECTRICAL NOTE: Except for the following changes, all information listed in Section 6Y o f the 1974 Light Duty Truck Overhaul Manual is applicable to 1976 light duty trucks. Refer to 1974 Overhaul Manual for any overhaul procedure not contained herein. STARTING MOTOR The 1976 starter is mostly carryover from 1974. The only difference being that the “ R ” terminal of the starter solenoid has been removed. This terminal was removed because with the High Energy Ignition System there is no longer any requirement for the electrical lead from the starter solenoid to the ignition coil. Refer to Section 6Y of the 1974 Overhaul Manual for all overhaul procedures. 10-SI SERIES 100 TYPE GENERATOR The 1976 10-SI generator is mostly carryover from 1974. The only difference being that a 40-ohm resistor has been added to the warning and indicator circuit (see Section 6Y in service section of this manual). The purpose of this resistor is to provide a definite warning indicator light in the case o f an open field circuit in the generator. Refer to Section 6Y of the 1974 Overhaul Manual for all overhaul procedures. STARTING SOLENOID The 1976 starter solenoid is mostly carryover from 1974. The only difference being that the “ R ” terminal of the solenoid has been removed. This terminal was removed because with the High Energy Ignition System there is no longer any requirement for the electrical lead from the starter solenoid to the ignition coil. Refer to Section 6Y of the 1974 Overhaul Manual for all overhaul procedures. SECTION 7M MANUAL TRANSMISSIONS CONTENTS OF THIS SECTION 3-Speed Tremec Transm ission.......................................................... 7M-1 4-Speed M uncie Transmission (CH 465)....................................... 7M-12 New Process Transfer Case Model 2 0 3 ......................................... 7M-15 3 SPEED - TREMEC MANUAL TRANSMISSION IN D E X Overhaul O perations........................................................ 7M-1 Transmission Disassembly............................................ 7M-1 Mainshaft Disassembly..................................................7M-3 Cleaning and Inspection............................................... 7M-3 Transmission C a se ....................................................... 7M-3 F ront and Rear Bearings............................................ 7M-3 Roller Bearings..............................................................7M-4 G ears................................................................................7M-4 Repairs...............................................................................7M-4 Synchronizer Keys and Spring..................................7M-4 Extension Oil Seal or B ushing..................................7M-5 Clutch Bearing Retainer Oil Seal............................. 7M-6 M ainshaft A ssem bly........................................................ 7M-6 Transmission A ssem bly...................................................7M-8 OVERHAUL OPERATIONS TRAN SM ISSIO N DISASSEMBLY 1. Remove lower extension housing bolt and drain transmission (fig. 3R). 2. Remove top cover and gasket from case. 3. Remove long spring that retains the detent plug in the case (fig. 4R). Remove the detent plug with a small magnet. 4 Remove extension housing and gasket. Fig. 1 R -3 -S p e e d T re m e c TR U C K SUPP - O V E R H A U L 7M -2 M A N U A L TRA N S M IS SIO N 5. Press down on speedometer gear retainer and remove speedometer drive gear and retainer from output shaft. 6. Remove fill plug from right side of case (fig. 3R). Working through the plug opening drive out countergear roll pin with a 3/16 inch pin punch that has been chamfered slightly. NOTE: Do not attem pt to retrieve pin at this time. Pin can easily be retrieved after output shaft assembly is removed. 7. Insert dum m y shaft tool J-25232 into bore at front of case, tap lightly on tool to push countershaft out rear of case (fig. 5R). NOTE: W ith countershaft removed, allow countergear to lie at bottom of case. 8. Punch alignm ent m ark in front bearing retainer and transmission case to ensure correct assembly and remove front bearing retainer and gasket (fig. 6R). 9. Remove large locating snap ring from front bearing and smaller snap ring from clutch gear shaft. 10. Remove clutch shaft front bearing using tool J-6654-01 and tool J-8433-1 (fig. 7R). NOTE: It may be necessary to alternate the tightening of the bolts between tools J-6654-01 and J-8433-1 to remove the front bearing. 11. Remove large locating snap ring from rear bearing and smaller retaining snap ring from output shaft. NOTE: It may be necessary to place a screwdriver or a piece of bar stock between the case and the first-reverse sleeve and gear assembly. This will hold the output shaft assembly in place while removing the rear bearing. NOTE: First and reverse sleeve and gear must pass through notch at right rear end of case. 20. Remove clutch gear through top of case. 21. Remove both shifter fork shafts (fig. 11R). 22. Remove countergear (with tool in place), thrust washers and roll pin. 23. Remove reverse idler gear and thrust washers by tapping shaft with ham m er until end of idler gear shaft (end with roll pin) clears counterbore in rear of case and remove shaft (fig. 12R). 24. From the bottom of the case retrieve, clutch shaft roller bearing or countergear needle bearing that may have fallen into case during disassembly. M AINSHA FT DISASSEMBLY 1. Remove snap ring from front of output shaft and remove Second-Third synchronizer assembly and second gear. M ark hub and sleeve for correct assembly. 2. Remove snap ring and tabbed thrust washer from shaft and remove first gear and blocking ring. 3. Remove First-Reverse hub retaining snap ring. NOTE: Observe position of spring and keys before removal, also, m ark hub and sleeve for correct assembly. 4. Remove sleeve and gear, spring and three keys from hub (fig. 13R). 5. Using an arbor press, remove hub from output shaft. 12. Remove rear bearing from output shaft using tool J-8 157-01 (fig. 8R). 13. Remove set screw from First-Reverse shifter fork and slide shift rail out rear of case. 14. Shift First-Reverse sleeve and gear all the way forward and rotate First-Reverse shifter fork upward and out of case. Remove First-Reverse D etent plug from case. 15. Shift Second-Third Shifter fork rearw ard to gain access to setscrew, remove setscrew, rotate shift rail 90° with pliers to clear bottom detent plug and remove interlock plug with magnet (fig. 9R). 16. Using a long thin punch (1 /4 inch diam eter or less) insert through access hole in rear case to drive out shift rail and expansion plug located in shift rail bore at front of case. CLEANING AND INSPECTION Transmission Case 1. Wash the transmission thoroughly inside and outside with cleaning solvent, then inspect the case for cracks. 2. Check the front and rear faces for burrs, and if present, dress them off with a fine mill file. Front and Rear Bearings 1. Wash the front and rear ball bearings thoroughly in a cleaning solvent. 2. Blow out bearings with compressed air. 17. Rotate second-third shifter fork upward and out of case. CAUTION: D o not allow the bearings to spin, turn 18. Remove the bottom detent plug and short detent spring from case. them slow ly by hand. Spinning bearings w ill damage the race and balls. 19. Separate clutch gear from output shaft and remove output shaft assembly (fig. 10R); tilt spline end of shaft downward and lift gear end upward and out of case. 3. Make sure bearings are clean, then lubricate with light engine oil and check them for roughness by slowly turning the race by hand. TRUC K S U P P - O V E R H A U L M A N U A L TRA N S M IS SIO N 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 3 \. 32. 33. 34. M A IN SH A FT ROLLER BEARINGS 2ND & 3RD SYNCHRONIZER RETA IN IN G RING SYNCHRONIZER BLOCKER RINGS 2ND & 3RD SYNCHRONIZER SPRING 2ND & 3RD SYNCHRONIZER SLEEVE 2ND & 3RD SYNCHRONIZER KEYS 2ND & 3RD SYNCHRONIZER HUB SECOND SPEED GEAR 1ST SPEED GEAR R ETA IN IN G RING 1ST SPEED GEAR TABBED WASHER 1ST SPEED GEAR REVERSE SYNCHRONIZER SPRING 1ST & REVERSE SYNCHRONIZER SLEEVE & GEAR REVERSE SYNCHRONIZER KEYS 1ST & REVERSE SYNCHRONIZER HUB 1ST & REVERSE SYNCHRONIZER RETA IN IN G RING REAR BEARING RETA IN IN G RING TRANSMISSION M AINSHAFT REVERSE-SYNCHRONIZER ASSEMBLY ACCESS COVER BOLTS ACCESS COVER ACCESS COVER GASKET BEARING R E T A IN E R -T O CASE BOLTS BEARING RETAINER CLUTCH GEAR GASKET - CLUTCH GEAR BEARING RETAINER SEAL ASSEMBLY - CLUTCH GEAR BEARING RETAINER CLUTCH GEAR BEARING RETAIN ING RING CLUTCH GEAR BEARING LOCK RING CLUTCH GEAR BEARING ASSEMBLY CLUTCH GEAR EXPANSION PLUG FILLER PLUG TRANSMISSION CASE MAGNET CASE 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 7M -3 EXTENSION HOUSING TO CASE GASKET SPEEDOMETER D R IVER GEAR R ETA IN IN G CLIP TRANSMISSION REAR BEARING LOCK RING M AIN SHA FT BEARING ASSEMBLY SPEEDOMETER D R IVE GEAR EXTENSION TO CASE WASHER EXTENSION TO CASE BOLT TRANSMISSION EXTENSION V EN TILA TO R ASSEMBLY EXTENSION HOUSING ASSEMBLY EXTENSION HOUSING BUSHING EXTENSION HOUSING O IL SEAL ASSEMBLY COUNTERGEAR THRUST WASHER COUNTERGEAR SPACER COUNTERGEAR ROLLET BEARINGS COUNTERGEAR SHAFT COUNTERGEAR SPRING PIN COUNTERGEAR 2ND & 3RD SHIFTER FORK SHIFT FORK LOCKING SCREW 1ST & 2ND SHIFTER INTERLOCK SPRING SHIFTER INTERLOCK PIN 1ST & REVERSE SHIFT R A IL 1ST & REVERSE SH IFT FORK 2ND & 3RD SHIFTER INTERLOCK SPRING 2ND & 3RD SHIFT RAIL REVERSE IDLER GEAR THRUST WASHER REVERSE IDLER GEAR SHAFT SPRING PIN IDLER GEAR SHAFT REVERSE IDLER GEAR BUSHING REVERSE IDLER GEAR REVERSE IDLER GEAR ASSEMBLY SEAL TRANSMISSION SHIFTER TRANSMISSION SHIFTER SHAFT & LEVER ASSEMBLY Fig. 2R -- Ex plo ded V i e w T r e m e c 3 - S p e e d T R U C K SUP P - O V E R H A U L 7M -4 M A N U A L T R A N S M IS SIO N NOTE: A L IG N ROLL PIN HOLE WHEN IN S T A L LIN G DU M M Y SH A FT TOOL J-25232 C O UNTERSHAFT A L IG N M E N T MARKS UPPER D ETEN T SPRING (LONG) Fig. 4 R ~ L o c a tio n o f U p p e r D e te n t S p rin g Bearing Rollers Fig. 6 R ~ R e m o v in g F ro n t B e a rin g R e ta in e r All clutch gear and countergear bearing rollers should be inspected closely and replaced if they show wear. Inspect REPAIRS countershaft and reverse idler shaft at the same time, replace Synchronizer Keys and Spring if necessary. Replace all worn washers. Replacement Gears 1. Inspect all gears for excessive wear, chips, or cracks and replace any that are worn or damaged. 2. Check both clutch sleeves to see that they slide freely on their hubs. 1. M ark hub and sleeve so they can be matched upon reassembly. 2. Push the hub from the sliding sleeve, the keys and the springs may be easily removed. 3. Install one spring into second-third hub. Be sure spring covers all three key slots in hub. Align second-third sleeve to hub using marks made during disassembly, and T R U C K SUP P - O V E R H A U L M A N U A L T R A N S M IS S IO N 7M -5 TU R N R A IL 90' J-6654-01 Fig. 7 R --R e m o v in g F ro n t B e a rin g BEA RING REM OVER TOO L J - 8 1 5 7 - 0 1 F ig . 9 R --R o ta tin g S h ift R ail F IR S T -R E V E R S E S L E E V E A N D G E A R IN F O R W A R D P O S IT IO N TO CLEAR CASE PULLER SCREWS F ig . 8 R --R e m o v in g R e a r B e a rin g start sleeve onto hub. 4. Place the three keys into hub slots and on top of spring, F ig . 1 0 R - R e m o v in g O u tp u t S h a ft A s s e m b ly NOTE: Keys have small lip on each end. When correctly installed, this lip will fit over spring (fig. 14R). then push sleeve fully onto hub to engage keys in sleeve Extension Oil Seal or Bushing (fig. 14). If bushing in rear of extension requires replacement, remove seal and use Tool J-5778 to drive bushing into extension housing (fig. 15R). Using the same tool, drive new bushing in from the rear. Coat I.D. of bushing and seal with transmission lubricant, then install new oil seal using Tool 5. Install remaining spring in exact same position as first spring. Ends of both spring must cover same slots in hub and not be staggered. TR U C K SUP P - O V E R H A U L 7M -6 M A N U A L T R A N S M IS S IO N SPRING" UNDER LIP OF O - RING LOCATION KEYS FIRST-REVERSE SLEEVE A N D GEAR HUB > R E T A IN IN G SNAP RING F ig . 1 1 R—S h ift F o rk S h a fts FIRST-REVERSE SY N C H R O N IZER F ig . 1 3 R --F irs t-R e v e rs e S y n c h r o n iz e r H u b A L IG N M E N T MARKS KEYS<3) A L IG N ROLL PIN W ITH COUNTERBORE WHEN IN STA LLIN G SPRING (UN DER LIP OF KEYS ) REVERSE IDLER GEAR SH A FT Fig. 1 2 R - R e m o v in g R e v e rs e Id le r G e a r S h a ft J-5154 (fig. 16R). Clutch Bearing Retainer Oil Seal If the lip seal in the retainer needs replacement; pry the old seal out and replace with a new seal using Installer Tool J-25233, or similar tool, until seal seats in its bore (fig. 17R). ASSEMBLY OF M AINSHA FT 1. Install First-Reverse synchronizer hub on output shaft splines by hand. Slotted end of hub should face front of shaft. Use an arbor press to complete hub installation on shaft and install retaining snap ring (in most rearward groove). CAUTION: D O N O T attem pt to drive hub onto shaft w ith hammer. Hammer blows w ill damage hub and splines. SLEEVE HUB F ig . 1 4 R --S e c o n d -T h ird S y n c h r o n iz e r A s s e m b ly Install First-Reverse sleeve and gear half-way onto hub with gear end of sleeve facing rear of shaft. Index sleeve to hub with marks made during disassembly. Install spring in First-Reverse hub. (Make sure spring is bottomed in hub and covers all three key slots.) Position three synchronizer keys in hub, with small ends in hub slots and large ends inside hub. Push keys fully into hub so they seat on spring. Then slide First-Reverse sleeve and gear over keys until the keys engage in the TR U C K SUP P - O V E R H A U L M A N U A L TR A N S M IS S IO N O IL RETURN SLOT 7 M -7 TOOL J-25233 J-5778 / FRO NT BEARING CAP F ig . 1 5 R—In s t a llin g E x te n s io n H o u s in g B u s h in g Fig. 1 7 R—In s t a llin g C lu tc h B e a rin g R e ta in e r S e a l TABBED THRUST WASHER (SHARP EDGE MUST FACE OUT) F ig . 18 R--I n s ta 11i ng T a b b e d T h r u s t W a s h e r F ig . 16 R—I n s ta 11i ng E x te n s io n H o u s in g S e a l synchronizer sleeve (fig. 13R). 4. Place first gear blocking ring on tapered surface of gear. Install First gear on output shaft. R otate gear until notches in blocking ring engages keys in First-Reverse hub. 5. Install tabbed thrust washer (sharp edge facing out) and retaining snap ring on output shaft (fig. 18R). 6. Place second gear blocking ring on tapered surface of gear and install second gear on output shaft with tapered surface of gear facing front of output shaft (fig. 19R). 7. Install Second-Third synchronizer assembly with flat portion of synchronizer hub facing rearward on output shaft. R otate Second gear until notches in blocking ring engages keys in Second-Third synchronizer assembly. NOTE: It may be necessary to tap synchronizer with a plastic ham m er to ease assembly. 8. Install retaining snap ring on output shaft and measure end play between snap ring and Second-Third synchronizer hub with feeler gauge (fig. 20R). End play TR U C K S U P P - O V E R H A U L 7M -8 M A N U A L TR A N S M IS S IO N SECOND GEAR I NOTE: Be sure to align and seat roll pin in shaft into counterbore in rear of case. 3. Measure reverse idler gear end play by inserting feeler gauge between thrust washer and gear. End play should be 0.004 to 0.018 inch. If end play exceeds 0.018 inch, remove idler gear and replace thrust washer. 4. Install shaft tool J-25232 in bore of countergear and load a row of needle bearing (25) in each end of gear. Use heavy grease or equivalent to hold them in place. Install one needle bearing retainer on each end of gear. 5. Position countergear thrust washer in case, use vaseline or equivalent to hold washers in place. NOTE: Be sure to engage locating tabs on thrust washer in locating slots in case. BLOCKING RING F ig . 19 R —In s t a llin g S e c o n d G e a r 6. Insert countershaft into bore at rear of case just far enough to hold rear thrust washer from being displaced when the countergear is installed. 7. Align bore in countergear with countershaft and front thrust washer, then start countershaft into countergear. Before countershaft is completely installed make sure that roll pin hole in countershaft is aligned with hole in case. When holes are aligned, tap countershaft into place, remove tool J-25232 (fig. 5R). 8. Measure countershaft end play by inserting feeler gauge between thrust washer and countergear. End play should be 0.004 to 0.018 inch. If end play exceeds 0.018 inch, remove gear and replace thrust washers. 9. After correct end play has been obtained, install roll pin in case. F ig . 2 0 R ~ M e a s u rin g O u tp u t S h a ft E nd P la y should be 0.004 to 0.0014 inch. If end play exceeds 0.014 inch, replace thrust washer and all snap rings on output shaft assembly. ASSEMBLY OF TRANSM ISSIO N 1. Coat transmission case reverse idler gear thrust washer surfaces with Vaseline (or equivalent) and position thrust washer in case. NOTE: Be sure to engage locating tabs on thrust washers in locating slots in case. 2. Install reverse idler gear with helical cut gear towards front of case. Align gear bore, thrust washers, case bores, and install reverse idler gear shaft from rear of case. 10. Lower shorter detent spring in detent bore in case (fig. 21R). Allow spring to drop into place at bottom of Second-Third shift rail bore. Insert lower detent plug in detent bore on top of spring. T R U C K SUP P • O V E R H A U L M A N U A L TRA N S M IS SIO N 7M -9 11. Install shifter fork shafts in their case bores with the pivot lug facing up. NOTE: Shifter fork shafts are interchangeable. 12. Install (15) roller bearings in clutch shaft bore. Use vaseline (or equivalent) to hold bearings in place. CAUTION: D o not use chassis grease o r a sim ilar "heavy" grease in clutch shaft bore. Heavy grease w ill p lu g the lubricant holes in the shaft and prevent proper lubrication o f the ro lle r bearing. 13. Install blocking ring on clutch gear and place clutch gear through top of case and position in front case bore. 14. Install output shaft assembly in case. Be sure First-Reverse sleeve and gear is in N eutral (centered) position on hub so gear end of sleeve will clear notch in top of case when output shaft assembly is installed. 15. Assemble the clutch gear to the output shaft. 16. Move Second-Third sleeve rearw ard to Second gear position and position Second-Third shifter fork in groove of sleeve. Be sure setscrew hold in shifter fork is facing up. Fig. 2 3 R --ln s ta llin g R ear B earin g N OTE: Second-Third fork is the smaller of the two shifter forks. 17. Engage Second-Third shifter fork in shifter fork shaft and insert Second-Third shift rail through front case bore and into shifter fork. N OTE: Tapered end of rail faces front of case. Fig. 2 4 R —In s ta llin g S p e e d o m e te r R e ta in e r and G e a r 20. Install interlock plug in detent bore. W ith Second-Third synchronizer in N eutral position, top of plug will be slightly below surface of First-Reverse shift rail bore. Fig. 2 2 R --ln s ta llin g F ro n t B earin g 18. T urn shift rail until detent notches in rail face bottom of case. Insert a phillips screwdriver in detent bore to depress lower detent plug and push shift rail into rear bore. Move rail inward until detent plug engages forward notch in shift rail (second gear position). 19. Secure fork to rail with setscrew and move second-third synchronizer to N eutral (centered) position. 21. Move first reverse synchronizer forward to first gear position. Place First-Reverse shifter fork in groove of sleeve. Be sure setscrew hole in fork is facing up. R otate fork into position in case, engage fork in shifter fork shaft, and insert First-Reverse shift rail through rear case bore and shifter fork. 22. Turn shift rail until detent notches in rail face upward. Move rail inward until setscrew hole in fork and setscrew bore in shift rail are aligned. Secure fork to rail with setscrew and place First Reverse sleeve and gear into N eutral (centered) position (fig. 20R). TRUCK SUPP • O VERH AUL 7M -10 M A N U A L TRA N S M IS SIO N 23. Install large snap ring on front bearing. 24. Install front bearing on clutch gear shaft by hand drive bearing on clutch gear shaft using tool J-24433 (fig. 22R). 25. Install smaller snap ring on clutch gear shaft. 26. Position bearing retainer gasket on case. Be sure cut-out in gasket is aligned with oil return hole in case. 27. Install front bearing retainer and tighten attaching bolts to 30 to 36 foot-pounds of torque. Be sure to index cap to case with alignment marks, and that oil return slot in cap is aligned with oil return hole in case. 31. Engage speedometer gear retainer in hole provided in output shaft, with retainer loop forward, slide speedometer gear over output shaft and into position (fig. 24R). Position extension housing gasket on case and install extension housing to case. Tighten bolts to 42 to 50 foot pounds torque. Install expansion plug in Second-Third shift rail bore in front of case. Be sure plug is fully seated in bore and is approximately 1/16 inch below front face of case. 28. Install large snap ring on rear bearing. Install upper detent plug in detent bore, then install long detent spring on top of plug. Install transmission fill plug and tighten 10 to 20 foot pounds torque. 29. Install rear bearing on output shaft by hand. Drive bearing onto shaft and into case with tool J-22609, make sure snap ring groove is facing rear of shaft (fig. 23R). Install top cover and gasket on case and secure with attaching bolts. Tighten bolts 20 to 25 foot pounds torque. 30. Install smaller snap ring on output shaft to hold rear bearing in place. If removed, install backup light switch in extension housing and TCS switch in case. Tighten switches to 15 to 20 foot pounds torque. TR U C K SUP P - O V E R H A U L M A N U A L TRA N S M IS SIO N 7M -11 SPECIAL TOOLS 1. J -2 4 4 3 3 FR O N T B E A R IN G INSTALLER 2 . J -2 2 6 0 9 REAR B E A R IN G INSTALLER 3 . J -2 5 2 3 2 C O U N T E R G E A R D U M M Y SH AFT 4 . J -8 4 3 3 -1 FR O N T B E A R IN G REM OVER 5 . J -6 6 5 4 -1 FR O N T B E A R IN G REM OVER 6. J -2 5 2 3 3 B E A R IN G R ETAIN ER O IL SEAL INSTALLER 7. J -5 1 5 4 E X T E N S IO N H O U S IN G SEAL INSTALL'ER 8 . J -5 7 7 8 E X T E N S IO N H O U S IN G B U S H IN G INSTALLER 9 . J - 8 1 5 7 -0 1 REAR B E A R IN G REM OVER F ig . 2 5 R --T re m e c S p e c ia l T o o ls T R U C K SUP P - O V E R H A U L 7M -12 M A N U A L TRA N S M IS SIO N FOUR-SPEED MUNCIE TRANSMISSION (CH 465) IN D E X Transmission A ssem bly..................................................................... M ainshaft A ssem bly........................................................................... 7M-12 7M-13 ASSEMBLY (Fig. 1X) 1. In reassembling the transmission cover, care must be used in installing the shifter shafts. They should be installed in the order shown in Fig. 2X, namely, reverse 3rd-4th and lst-2nd. Figure IX illustrates difference between shafts. 2. Place fork detent ball springs and balls in position in holes in cover. 3. Start shifter shafts into cover; depress dentent balls with small punch and push shafts on over balls. (See Fig. 2X). Hold reverse fork in position and push shaft through yoke. Install split pin in fork and shaft; then, push fork in neutral position. 4. Hold 3rd and 4th fork in position and push shaft through yoke, but not through front support bore. 5. Place two (2) interlock balls in cross-bore in front support boss between reverse and 3rd and 4th shifter shaft. Install the interlock pin in the 3rd and 4th shifter shaft hole and grease to hold in place. Push 3rd and 4th \ 12 1. 2. 3. 4. 5. 6. 7. Transmission Cover Interlock Balls 3rd-4th Shifter Shaft Reverse Shifter Shaft Fork Retaining Pin Detent Ball Detent Spring 8. 3rd-4th Shifter Fork 9. "C" Ring Lock Clip 10. Reverse Shifter Fork 11. Shifter Shaft Hole Plugs 12. 1st-2nd Shifter Fork 13. 14. 15. 16. 17. 11 Interlock Plunger Spring Reverse Interlock Plunger 1st-2nd Shifter Shaft Interlock Pin Cover Gasket Fig. 1 X - C o v e r A s s e m b ly - Exp lo de d V i e w TR U C K S UPP - O V E R H A U L M A N U A L T R A N S M IS S IO N shaft through fork and cover bore keeping both balls and pin in position between shafts until retaining holes line up in fork and shaft. Install retaining pin and move to neutral position. 6 . Place two (2) interlock balls between the 1st and 2nd shift shaft and 3rd and 4th shifter shaft in the cross-bore of the front support boss. Hold 1st and 2nd fork in position and push shaft through cover bore in fork until retainer hole and fork line up with hole in shaft. Install retainer pin and move to neutral position. 7. Install new shifter shaft hole expansion plugs and expand in place. 7 M -1 3 2. Remove snap ring in front of 3rd-4th synchronizer assembly. 3. Remove reverse driven gear. 4. Press behind second speed gear to remove 3rd-4th synchronizer assembly, 3rd speed gear and 2nd speed gear along with 3rd speed gear bushing and thrust washer (fig. 4X). 5. Remove 2nd speed synchronizer ring. 6. Supporting 2nd speed synchronizer hub at front face, press mainshaft through removing 1st speed gear bushing and 2nd speed synchronizer hub. 7. Split 2nd speed gear bushing with chisel and remove bushing from shaft. M A INSHA FT ASSEMBLY Disassembly (Fig. 3X) 1. Remove first speed gear and thrust washer. CAUTION: Exercise care not to damage mainshaft. F ig . 2 X - S h if t e r S h a ft In s ta lla tio n T R U C K SUP P - O V E R H A U L 7 M -1 4 M A N U A L T R A N S M IS S IO N 1. 1s t S p e e d G e a r 2 R e v e rs e D riv e n G e a r 3. 1 s t G e a r B u s h in g 6 2nd S peed G ear 3 rd -4 th S pee d 1 4. S n a p R in g 4 1 s t- 2 n d G e a r 7. T h ru s t W a s h e r S y n c h r o n iz e r H u b 15 . M a in s h a ft S y n c h r o n iz e r H u b 8. 3 r d S p e e d B u s h in g A s s e m b ly 1 6. A s s e m b ly 9 3 rd S p e e d G e a r 5 2 n d S p e e d B lo c k e r 10. R in g 3 r d S p e e d B lo c k e r 13 . R in g 1 1. 1 2. 3 rd -4 th S pee d 4 th S p e e d B lo c k e r R in g 2n d S peed G ear B u s h in g S y n c h r o n iz e r S le e v e F ig . 3 X - - M a in s h a ft A s s e m b ly E x p lo d e d V ie w T R U C K SUP P - O V E R H A U L M A N U A L T R A N S M IS S IO N 7 M -1 5 3R D G EAR ND GEAR F ig . 4 X --D is a s s e m b ly o f M a in s h a ft NEW PROCESS TRANSFER CASE MODEL 203 IN D E X Disassembly of transfer c a se ............................................................. 7M-15 R ear O utput Shaft Housing (Rear) Assembly............................. 7M-19 R ear O utput Shaft Housing (Front) A ssem bly........................... 7M-20 Assembly of Transfer Case................................................................ 7M-20 DISASSEMBLY OF TRANSFER CASE Refer to figures 1F and 2F for cross sectional 7. Remove bolts retaining front section of rear output housing assembly from transfer case. Remove housing from transfer case. 1. Position transfer case on work bench or suitable work table (Fig. 3F and 4F). 8. Remove "O" ring seal from front section of rear output housing and discard. NOTE: If lubricant was not drained from unit prior to removal from vehicle, remove front output rear cover and P.T.O. cover lower bolts and drain lubricant into waste container. 9. Disengage rear output shaft from differential carrier assembly. 2. Using Tool J-8614-1, loosen rear output shaft flange retaining nut. 3. Using Tool J-8614-1, remove front output shaft flange retaining nut, washer and flange. NOTE: Tap dust shield rearw ard on shaft (away from bolts) to obtain clearance to remove bolts from flange and allow installation of Tool J-8614-1. 4. Remove bolts retaining front output shaft front bearing retainer. Remove bearing retainer and gasket from transfer case. Discard gasket. 5. Using a hoist or other suitable lifting tool, position assembly on blocks. 6. Remove bolts retaining rear section of rear output housing assembly from front section of rear output housing and disengage. Remove shims and speedometer gear from output shaft. 10. Slide carrier unit from shaft. NOTE: A 1-1/2" to 2" water hose band type clamp may be installed on the input shaft at this time to prevent loosing bearings when removing input shaft assembly from the range box. 11. Raise shift rail and drive out pin retaining shift fork to rail. 12. Remove shift rail poppet ball plug, gasket spring and ball from case. A small magnet may be used to remove ball from case. 13. Push shift rail down, lift up on lockout clutch and remove shift fork from clutch assembly. 14. Remove bolts retaining front ouput shaft rear bearing retainer to transfer case. Tap on front of shaft or carefully pry retainer away from case. Remove retainer from shaft and discard gasket. Recover any roller bearings which may fall from rear cover. TR U C K S UPP - O V E R H A U L 7 M -1 6 M A N U A L T R A N S M IS S IO N 1 . A d a p te r 22 . 2 . In p u t D riv e Gear P ilo t Brgs. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 3. 4. 5. Range S e le c to r S lid in g C lu tc h Range S e le c to r H ousin g L o w Speed Gear B ushing 6 . L o w Speed Gear 7. T h ru s t W asher & L o c a tin g Pin 8 . G asket 9. In p u t Brg. R e ta in e r 10. In p u t Brg. 11 . Brg. O u te r R ing 12. Brg. R e ta in in g R ing 13. T h ru s t W asher, L o c a tin g P in, L u b ric a tin g W asher & Spacer 14. In te rm e d ia te (C ha in H ousin g) 15. D rive S h a ft S p ro c k e t 16. G asket 17. S lid in g L o c k C lu tc h 18. Rear O u tp u t H o usin g 19. Rear O u tp u t F r o n t Brg. 20 . V e n t 2 1 . O il Seal O il P um p S pee dom e ter D rive Gear Brg. R e ta in e r Ring Rear O u tp u t Rear Brg. Rear O u tp u t S h a ft W asher Locknut R u b b e r S p lin e Seal Rear O u tp u t Y o k e Rear O u tp u t Seal S him s In p u t S h a ft " O " R ing In p u t S h a ft P ilo t Bearings D iffe re n tia l C a rrie r A sse m b ly S p rin g W asher C up L o c k o u t C lu tc h S p rin g Snap R ing Snap R ing F r o n t O u tp u t Rear Brg. C over F r o n t O u tp u t Rear Brg. F r o n t O u tp u t D riv e S p ro c k e t G asket 44 . 45 . 46 . 47 . 48 . 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63 . 64 . 65. M a gnet D riv e C hain G asket Brg. O u te r R ing F r o n t O u t p u t F r o n t Brg. F r o n t O u tp u t S h a ft Seal F r o n t O u tp u t Brg. R e ta in e r R u b b e r S p lin e Seal Locknut F r o n t O u tp u t Y o k e C o u n te rg e a r C o u n te rg e a r Spacers and Brgs. C o u n te rg e a r S h a ft C o u n te rg e a r T h ru s t W asher G asket Brg. R e ta in e r G asket Brg. O u te r R ing In p u t Gear Brg. In p u t Gear Seals (2) Brg. Snap R ing In p u t Gear In p u t Gear Brg. R e ta in e r Fig. 1 F -N e w P rocess T ra n s fe r C ase - Cross S e c tio n TR U C K S UPP - O V E R H A U L M A N U A L T R A N S M IS S IO N 7 M -1 7 Fig. 2 F -1 -T r a n s fe r C ase E xploded V ie w TRUC K S U P P - O V E R H A U L 7 M -1 8 M A N U A L T R A N S M IS S IO N <3b 85 1. 2. 3. 4. 5. 6. 7. Adapter P.T.O. Cover Selector Housing to Chain Housing Gasket 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. Detent Plate Spring Plug Gasket D etent Plate Spring Detent Plate Locko ut S h ifte r Shaft " O " Ring Seal Lo cko u t Shaft Connector Link " 0 " Ring Seal Range Selector S h ifte r Shaft Range Selector S h ift Fork Detent Plate Pivot Pin Thrust Washer Spacer (short) Range Selector Counter Gear 88 89 90 91 92 50. Retaining Ring 51. Flange Lock N ut 52. Seal 53. F ro n t O u tp u t Yoke 54. Dust Shield 55. F ro n t O u tp u t Shaft Bearing Retainer Seal 56. F ro n t O u tp u t Shaft Bearing Retainer 57. F ro n t O u tp u t Shaft Bearing 58. Bearing O uter Ring 59. Bearing Retainer Gasket 60. F ro n t O u tp u t Shaft 61. F ro n t O u tp u t Shaft Rear Bearing 62. F ro n t O u tp u t Rear Bearing Retainer Cover Gasket 63. F ront O u tp u t Rear Bearing Retainer 64. Orive Shaft S procket 65. Drive Chain 66. Retaining Ring 67. S liding Lock Clutch 68. L ocko ut S h ift Rail 69. S h ift F ork Retaining Pin 70. L o c k o u t S h ift Fork 71. L o c k o u t Clutch Spring 72. Spring Washer Cup 73. F ro n t Side Gear 74. F ro n t Side Gear Bearing and Spaces (123 Bearings Req'd.) 75. D iffe re n tia l Carrier Assembly (132 Bearings Req'd.) 76. Rear O u tp u t Shaft R oller Bearings (15 Req'd.) 77. Rear O u tp u t Shaft 78. Speedometer Drive Gear 79. Rear O utpu t Shaft F ro n t R oller Bearing Main Drive In p u t Gear Range Selector Sliding Clutch 15. S h ift Lever Lock N ut 16. Range Selector S h ift Lever 17. S h ift Lever Retaining Ring 18. L ocko ut S h ift Lever 19. D etent Plate Spring Plug 35. 36. 37. 87 48. T hrust Washer 49. Lub ricating T h ru st Washer In p u t Gear Bearing detainer In p u t Gear Bearing Retainer Gasket In p u t Gear Bearing Retainer Seals Bearing O uter Ring Bearing to Shaft Retaining Ring Input Gear Bearing 8. Adapter to Selector Housing Gasket 9. Range Selector Housing (Range Box) 10. P.T.O. Cover Gasket 11. 12. 13. 14. 86 Countergear Roller Bearings and Spacers (72 Bearings Req'd.) Countergear Shaft Thrust Washer In p u t Shaft Roller Bearings (15 Req'd.) Thrust Washer Pins (2 Req'd.) In p u t Shaft 38. 39. " 0 " Ring Seal 40. Low Speed Gear and Bushing 41. T h ru st Washer 42. In p u t Shaft Bearing Retainer 80. O il Pump " 0 " Ring Seal 81. Rear O u tp u t Housing Gasket 82. Rear O u tp u t Housing (F ro n t) 83. " 0 " Ring Seal 84. Rear O u tp u t Housing (Rear) 85. Shim Pack 86. Bearing Retainer 87. Rear O u tp u t Rear Bearing 88. Rear O u tp u t Shaft Seal 89. Rear O utpu t Flange 43. In p u t Shaft Bearing 44. In p u t Shaft Bearing Retaining Ring (Large) 45. In p u t S h a ft Bearing Retaining Ring 46. Chain Drive Housing 47. L o cko u t S h ift Rail Poppet Plug, Gasket, Spring and Ball. 90. Rear O utpu t Shaft Rubber Seal 91. Washer 92. Flange N ut Fig. 2 F -2 -T r a n s fe r C ase E xploded V ie w T R U C K SUP P - O V E R H A U L M A N U A L T R A N S M IS S IO N 7 M -1 9 20. Pull up on shift rail and disconnect rail from link. INPUT G EAR 21. Remove (lift) input shaft assembly from range box. NOTE: At this point the transfer case is completely disassembled into its subassemblies. Each of these subassemblies should then be disassembled for cleaning and inspection. FRONT O U TPUT SHAFT ASS Y . REAR OUTPUT SHAFT HOUSING (REAR) ASSEMBLY Disassembly 1. Remove speedometer driven gear from rear section of rear output housing. C H A IN H O U S IN G RANGE H O U S IN G COUNTER GEAR 3. Using a screwdriver, pry behind open ends of snap ring and remove snap ring retaining rear bearing in housing (Fig. 5F). F ig . 3 F - F r o n t V ie w o f T r a n s fe r C ase REAR OUTPUT HOU 2. Pry old seal out of bore, using a screwdriver or other suitable tool. L O C K O U T CLUTCH SHIFT RAIL POPPET PLUG R A N G E SELECTOR HIFTER SHAFT C H A IN S IN G FRO N T OUTPUT | BEA R IN G REAR C OVER Fig. 4 F -R e a r V ie w o f T r a n s fe r C a se Fig . 5 F -R e m o v in g R e a r O u t p u t B e a rin g R e ta in in g R ing NOTE: If necessary to replace rear bearing, support cover and press bearing from cover. Position new bearing to outside face of cover and press bearing into cover with a .06 overhang. 15. From lower side of case, remove (pry) output shaft front bearing. 16. Disengage front output shaft from chain and remove shaft from transfer case. 17. Remove bolts attaching intermediate chain housing to range box. Lift or using a chain hoist, remove intermediate housing from range box. 18. Remove chain from interm ediate housing. 19. Remove lockout clutch, drive gear and input shaft assembly from range box. NOTE: A 1-1/2" to 2" hose clamp may be installed on end of the input shaft to prevent loosing the roller bearings (123) which may fall out of clutch assembly if it is pulled off the input shaft. 4. Pull or tap bearing from housing. 5. To remove the front bearing, insert a long drift through rear opening and drive bearing from housing (Fig. 6F). Remove and discard rubber seal. Assembly 1. Position rear bearing in housing and tap into place. 2. Install snap ring retaining bearing to case. NOTE: Retaining Ring is a select fit. Use service ring size A, B, C or D as required to provide tightest fit. 3. Position rear seal to bore and drive into place using tool J-22388 (Fig. 7F) or^ other suitable tool until approximately 1/8" to 3/16" below housing face. 4. If the vent seal falls out or is knocked out during disassembly, reinstall new seal or thoroughly clean and dry the area and re-cement the old seal in place. TRUC K S U P P - O V E R H A U L 7 M -2 0 M A N U A L T R A N S M IS S IO N Assembly 1. Position rubber seal in bearing bore. Use grease to hold in place. Position roller bearing in bore and press into place until bearing bottoms out in housing. 2. Position new "O" ring on housing. ASSEMBLY OF TRANSFER CASE (FIGS. IF 1. Place range box on blocks, with input gear side toward bench. 2. Position range box-to-transfer case housing gasket on input housing. 3. Install lockout clutch and drive sprocket assembly on the input shaft assembly. NOTE: A 2" band clamp may be installed on end of shaft to prevent loosing bearings from clutch assembly. 4. Install input shaft, lockout clutch and drive sprocket assembly in the range box, aligning tab on bearing retainer with notch in gasket. F ig . 6 F -R e m o v in g R e a r O u tp u t S h a ft F ro m B e a rin g 5. Connect lockout clutch shift rail to the connector link and position rail in housing bore. Rotate shifter shaft lowering shift rail into the housing, to prevent the link and rail from being disconnected. 6. Install drive chain in chain housing, positioning the chain around the outer wall of the housing. 7. Install the chain housing on the range box engaging the shift rail channel of the housing to the shift rail. Position chain on the input drive sprocket. 8. Install the front output sprocket in the case, engaging the drive chain to the sprocket. R otate clutch drive gear to assist in positioning chain on the drive sprocket. 9. Install the shift fork on the clutch assembly and the shift rail, then push the clutch assembly fully into the drive sprocket. Install roll pin retaining shift fork to shift rail. 10. Install front output shaft bearing. 11. Install front output shaft bearing retainer, gasket and retaining bolts. 12. Install the front output shaft flange, gasket, seal, washer and retaining nut. Tap dust shield back in place after installing bolts in flange. F ig . 7 F—In s ta llin g R e a r O u t p u t H o u s in g S e a l REAR OUTPUT SHAFT HOUSING (FRONT) Disassembly 1. Remove "O" ring from rear output shaft housing (front) and discard. 2. To remove roller bearings from housing, insert a long drift through rear opening and drive bearing from housing (Fig. 6F). Remove and discard rubber seal. 13. Install front output shaft rear bearing retainer, gasket and retaining bolts. NOTE: If rear bearing was removed, position new bearing to outside face of cover and press into cover until bearing is flush with opening. 14. Install differential carrier assembly on the input shaft. Carrier bolt heads should face rear of shaft. 15. Position rear output shaft to differential carrier assembly (load bearings in pinion shaft). 16. Install rear output housing (front) assembly, gasket, and retaining bolts. 17. Install speedometer gear and shims (approximately .050 inch thickness) on output shaft. TR U C K S U P P - O V E R H A U L M A N U A L T R A N S M IS S IO N 18. Position rear output housing (rear) assembly to rear output housing (front). Be sure "O" ring is in proper position on front section of output housing. NOTE: Be sure vent is in upward position. 19. Install flange, washer, and retaining nut. Leave nut loose (approximately .060 inch) until shim requirements are determined. 20. Install shim pack onto shaft, in front of rear bearing, to control end play to within 0 to .005". Hold rear flange and rotate front output shaft to check for binding of the rear output shaft. 7M -21 21. Install speedometer driven gear in housing. 22. Install lockout clutch shift rail poppet ball, spring and screw plug in case. 23. Install poppet plate spring, gasket and plug, if not installed during reassembly of range box. 24. Install shift levers on the range box shifter shaft, if not left on linkage in vehicle. 25. Torque all bolts, locknuts and plugs (except filler plug) to specifications. 26. Fill transfer case to proper level with specified lubricant. 27. Install and tighten filler plug to specifications. T RUC K SUP P - O V E R H A U L SECTION 7A AUTOMATIC TRANSMISSIONS CONTENTS OF THIS SECTION Turbo H ydra-M atic 350 Transm ission........................................... Turbo H ydra-M atic 375/400/475 T ransm ission......................... 7A-1 7A-3 TURBO HYDRA-MATIC 350 TRANSMISSION DISASSEMBLY 1. Install Holding Fixture J-8763-02 on transmission and place into Holding Tool base J-3289-20 with converter facing upward. O ” RING SEAL NOTE: Cleanliness is an im portant factor in the overhaul of the transmission. Before attem pting any disassembly operation, the exterior of the case should be thoroughly cleaned to prevent the possibility of dirt entering the transmission internal mechanism. D uring disassembly, all parts should be thoroughly cleaned in cleaning fluid and then air dried. Wiping cloths or rags should not be used to dry parts. VACUUM MODULATOR CAUTION: D o not use solvents which could damage rubber seals o r clutch facings. 2. W ith transmission in holding fixture remove torque converter assembly. 3. Remove vacuum m odulator assembly attaching bolt and retainer. 4. Remove vacuum m odulator assembly, "O" ring seal, and m odulator valve from case (fig. 1A). Discard "O" ring. INSPECTION OF CONVERTER Fig. 1 A -R e m o v in g V a c u u m m o d u la to r A s s e m o iy 3. Install Tool J-21371-3 and tighten hex nut to 3 ft. lbs. (fig. 5A). 4. Install Dial Indicator J-8001 and set it at "zero", while 1. Check converter for leaks as follows (fig. 3A): a. Install Tool J-21369 and tighten. b. Apply 80 psi air pressure to tool. its plunger rests on the cap nut of Tool J-21371-8. 5. Loosen hex nut while holding cap nut stationary. W ith c. Submerge in water and check for leaks. 2. Check converter hub surfaces for signs of scoring or wear. CONVERTER END CLEARANCE CHECK (Figs. 4A and 5A) the hex nut loosened and holding Tool J-21371-3 firmly against the converter hub, the reading obtained on the dial indicator will be the converter end clearance. End 1. Fully release collet end of Tool J-21371-8. 2. Install collet end of Tool J-21371-8 into converter hub until it bottoms; then tighten cap nut to 5ft. lbs. (fig. 4A). clearance should be less than .050". If the end clearance is .050" or greater, the converter must be replaced. T RUC K SUP P - O V E R H A U L 7A -2 A U T O M A T IC T R A N S M IS S IO N CLUTCH ASSEMBLIES FOR THM 3 50 CLUTCH D R IVE PLATE DRIVEN PLATES CUSHION SPRING 4 4 1 5 5 1 2 2 1 3 3 1 3 3 NONE 4 4 NONE 4 4 NONE 5 5 NONE FORWARD 250 L-6, 262-305 V-8 350 V-8, 400 V-8 T A X I AND TRUCK IN TER M E D IA TE 250 L-6, 262 V-8 305-350 V-8, 400 V-8 T A X I AND TRUCK DIRECT 250 L-6, 262 V-8 305-350 V-8, 400 V-8 T A X I AND TRUCK REVERSE 250 L-6, 262-305 V-8 Fig. 3 A -A ir Checking Converter 350 V-8, 400 V-8 T A X I AND TRU CK Fig. 2 A -A u to m a tic Clutch Chart Fig. 4A-Loosening Collet on Tool J -2 1 5 7 1 -8 Fig. 5A -C hecking Converter End Clearance T R U C K SUP P - O V E R H A U L A U T O M A T IC T R A N S M IS S IO N 7A -3 TURBO HYDRA-MATIC 3 7 5 /4 0 0 /4 7 5 TRANSMISSION IN D E X R ear Servo, Valve Body Spacer, Gasket, and Front Servo............................................................7A-3 Oil Pum p and Internal Case C om ponents...............7A-4 Speedometer Drive G e a r.............................................. 7A-4 Control Valve.................................................................. 7A-5 Forw ard C lutch............................................................... 7A-7 Direct C lu tc h .................................................................. 7A-9 Center Support................................................................ 7A -10 Reaction Carrier, Roller Clutch and Output Carrier Assem bly..............................................................7A -10 Front and Rear Bands, Support to Case Spacer.... 7A -10 Case Extension (Except CL M odel)..........................7A -10 Case Extension - CL M o d e l....................................... 7A -11 Case Assembly................................................................ 7A-11 Rear U n it......................................................................... 7A -11 Units to Transmission C ase........................................ 7A -11 Case Extension..................................................... .......... 7A-11 Check Balls, Control Valve Spacer Plate and Gasket, D etent Solenoid, Front Servo Assembly, and Electrical C onnector......................................................7A-12 M odulator Valve and Vacuum M odulator.............. 7A-12 Converter Assembly.......................................................7A-12 REAR SERVO, VALVE BODY SPACER, GASKET AND FRONT SERVO Removal 1. Remove rear servo cover attaching screws, servo cover and gasket. Discard gasket. 2. Remove rear servo assembly from case (fig. IB). 3. Remove rear servo accum ulator spring. Rear Band Apply Pin Selection M odel "CL " 4. M ake band apply pin selection check to determine possible cause of malfunction. NOTE: There are six selective pins identified as shown in figure 3B. Selecting proper pin is equivalent to adjusting band. a. A ttach band apply pin selection gauge (J-21370-9 and J-2 1370-6), to transmission case (lever pivot pin to rear) with rear servo cover attaching screws (fig. 2B). b. A ttach tool attaching screws finger tight and check freeness of selective pin. Torque attaching screws to 15 foot-pounds and recheck pin to make certain it does not bind. c. Apply 25 foot-pounds torque to the lever on Tool J-2 1370-6 (fig. 2B). Selection of the proper rear band apply pin is determined by the relation of the flat on Tool J :2 1370-9 to the flat machined area around the T R U C K SUP P - O V E R H A U L 7A -4 A U T O M A T IC T R A N S M IS S IO N hole on Tool J-2 1370-6. d. Before removing gauging tool make note of the proper band apply pin to be used during assembly of the transmission as determined by the six selective pins identified as shown in figure 3B. Selecting proper length pin is equivalent to adjusting band. The band lug end of each selective apply pin bears identification in the form of one, two or three rings. c. If both steps of J-2 1370-5 are below the gauge surface, the long pin, identified by 3 rings, should be used. d. If the gauge surface is between the steps, the medium pin, identified by 2 rings, should be used. e. If both steps are above the gauge surface, the short pin, identified by 1 ring, should be used. NOTE: If the transmission is in the vehicle, be careful when the detent solenoid is removed as it prevents the spacer plate and gasket and check balls from dropping down. 5. Remove detent solenoid solenoid and gasket. attaching screws, detent 6. W ithdraw electrical connector and "O" ring seal. 7. Remove control valve assembly spacer plate and gasket. 8. Remove six ( 6) check balls from cored passages in transmission case. NOTE: M ark location of balls for aid in reassembly. 9. Remove front servo piston, retainer ring, washer, pin, spring retainer and spring from transmission case. Fig. 1B-Rem oving Rear Servo Assembly OIL PUMP AND INTERNAL CASE COMPONENTS Removal Delete step num ber 13 from removal procedure as found in 1974 Overhaul Manual. SPEEDOMETER DRIVE GEAR Replacement If removal and installation or replacement of the speedometer drive gear is necessary, proceed as follows: Nylon Speedometer Drive Gear 1. Depress clip and slide speedometer drive gear off output shaft. 2. To install, place clip (square end toward flange of shaft) into hole in output shaft. Align slot in speedometer drive gear with clip and install gear. Fig. 2B -C hecking Rear Band Apply Pin - M odel "CL" "All Models Except CL " a. A ttach band apply pin selection Gauge J-2 1370-5 and J-2 1370-6 to transmission case with attaching screws checking to make certain the gauge pin does not bind in servo pin hole (fig. 4B). b. Apply 25 ft. lb. torque and select proper pin to be used during assembly of transmission. NOTE: The nylon speedometer drive gear is installed at the factory only. A LL service replacement speedometer drive gears are STEEL. When replacing the nylon speedometer drive gear with a steel gear, discard the retaining clip and refer to Step "2" of steel speedometer drive gear installation. Steel Speedometer Drive Gear 1. Install speedometer drive gear remover Tool J-2 1427-01 and J-9539 bolts with J-8105 or suitable puller on output shaft, and remove speedometer drive gear (fig. 5B). 2. Install new steel speedometer drive gear and drive to location (5-43/64" below end of output shaft for all models except CA, CG and CR) (11-15/64" below end TRUCK SUPP - OVERH AUL A U T O M A T IC T R A N S M IS S IO N GAGING STEPS LOCATED ON THREE SIDES OF TOOL J-21370-9 7A -5 PIN D E N TIFIC A TIO N PART NO. r u THIS STEP: USE PIN NO. 8627195 LONGEST PIN I THIS STEP: SIDES B TO C USE PIN NO. 8627194 Oi o co t— B THIS STEP: USE PIN NO. 8624141 mtQ THIS STEP: SIDES A TO B USE PIN NO. 8627193 t=Q CM LOWER STEP SHORTEST PIN Note: THIS STEP: USE PIN NO. 8624140 □EG LOWER STEP: USE PIN NO. 8627192 btQ The Identification Rings are .030" and .100" wide. Fig. 3 B -R e a r Band Apply Pin Identification Fig. 4B -C hecking Rear Band Apply Pin "All M odels Except CL" of output shaft for models CA) (11-29/64 below end of output shaft for models CG and CR) using J-5590 (fig. 6B). Fig. 5B -R em oving Steel Speedom eter Drive Gear 2. Remove manual valve from upper bore. CONTROL VALVE 3. Install Special Tools J-22269 and J-24675, on Disassembly accum ulator piston and remove retaining ring (fig. 8B). 1. Position control valve assembly with cored face up and accum ulator pocket nearest operator. A- ccum ulator Piston T R U C K SUPP - O V E R H A U L 7 A-6 A U T O M A T IC T R A N S M IS S IO N Inspection IN S T A L L E R S P E E D O M E TE R GEAR NOTE: See figure 9B. D o not remove the teflon oil seal ring from the front accum ulator piston unless the oil seal ring requires replacement. For service, the oil seal ring is cast iron. 1. Inspect all valves for scoring, cracks and free movement in their respective bores. 2. Inspect bushings for cracks, scratches or distortion. 3. Inspect body for cracks, or scored bores. 4. Check all springs for distortion or collapsed coils. 5. Inspect accum ulator piston and oil seal ring for damage. Assembly 1. Install front accum ulator spring and piston into valve body. 2. Install Special Tools J-22269 and J-24675 and compress spring and piston and secure with retaining "E" ring. 3. Install the 1-2 accum ulator valve train into the lower left hand bore as follows: Fig. 6 B—I n s ta llin g S te e l S p e e d o m e te r D riv e G e a r 4. Remove front accum ulator piston and spring (fig. 9B). 5. On the right side adjacent to the manual valve, remove the 1-2 valve train as follows: a. All models except CJ and CP, remove the retaining pin, 1-2 m odulator bushing, 1-2 regulator valve, 1-2 regulator spring, 1-2 detent valve and 1-2 shift valve. b. Models CJ and CP, remove the retaining pin, 1-2 m odulator bushing, 1-2 m odulator spring, 1-2 m odulator valve and 1-2 shift valve. 6. From next bore down, remove retaining pin, 2-3 shift valve spring, 2-3 m odulator valve bushing, 2-3 m odulator valve, 3-2 interm ediate spring, and 2-3 shift valve. 7. From next bore down remove retaining pin, bore plug, spring, spacer, and 3-2 valve. 8. At other end of assembly, top bore, remove retaining pin and bore plug, detent valve, detent regulator valve, spring and spacer. 9. From the next bore down, remove the 1-2 accum ulator valve train as follows: a. (Models CA, CG, CP and CR) remove the grooved retaining pin, bore plug, 1-2 accum ulator valve and spring. b. (Models CJ and CL) Remove the grooved retaining pin, bore plug, 1-2 accum ulator valve. c. (Models CT, CM and CZ) Remove the grooved retaining pin, bore plug, 1-2 accum ulator secondary spring and 1-2 accum ulator valve. a. (Model CA, CG, CP and CR) Install the 1-2 accum ulator spring and 1-2 accumulator valve, stem end out, into bore. Place the bore plug into valve bore and install grooved retaining pin from cast surface side of the valve body, with the groove entering the pin holes last. Tap pin with a ham m er until flush with cast surface of valve body. b. (Models CJ and CL) Install 1-2 accumulator valve stem end out, into bore. Place bore plug into valve bore and install grooved retaining pin from cast surface side of the valve body, with the groove entering the pin holes last. Tap pin with a hammer until flush with cast surface. c. (Models CT, CM and CZ) Install the 1-2 accum ulator valve, stem end out, and 1-2 accum ulator secondary spring. Install the bore plug and compress spring until grooved retaining pin can be inserted from the cast surface side of the valve body. Install retaining pin with the grooved end entering the pin hole last and tap in place until flush with cast surface of the valve body. 4. In next bore up, install detent spring and spacer. Compress spring and secure with small screwdriver (fig. 10B). 5. Install detent regulator valve, wide land first. 6. Install detent valve, narrow land first. 7. Install bore plug (hole out), depress spring by pressing in on plug, install retaining pin, and remove screwdriver. 8. In lower right hand bore, install 3-2 valve. 9. Install 3-2 spring, spacer, bore plug (hole out) and retaining pin. 10. In next bore up, install the 2-3 shift valve, open end out, into the bore and install 3-2 intermediate spring. TRUCK SUPP - O VERHAUL A U T O M A T IC T R A N S M IS S IO N 11 12 mb 7A -7 13 || '[iiiiBiiiilifr nil a iu n u » tt I g Q y ^ j A 21 V 22 23 28 M O D E LS CJ & CL l vimm 14 15 29 16 M O D ELS C D , CF, C G , ^CM , CP, CR, CT, & CZ 1. M a n u a l V a lv e 9. 2. R e ta in in g P in 10. 3. B o re P lu g 4. D e te n t V a lv e 5. D e te n t R e g u la to r 1-2 D e te n t V a lv e S p r in g 1 1. 12. V a lv e 16. 1-2 R e g u la to r V a lv e 17. 1-2 R e g u la to r V a lv e 1-2 M o d u la to r 18. B u s h in g 19. 6. S pacer 13. R e ta in in g Pin 7. D e te n t R e g u la to r 14. R e ta in in g Pin 20. V a lv e S p r in g 15. B o re P lu g 21 8. 1-2 A c c u m u la to r 2 -3 M o d u la t o r B u s h in g 23 A c c u m u la to r S p r in g 24 3 -2 V a lv e 2 -3 S h if t V a lv e 25 Spacer 3 -2 V a lv e S p r in g R e ta in in g P in 3 -2 In t e r m e d ia te 26. S p r in g 27. B o re P lu g 2 -3 M o d u la t o r V a lv e 28. R e ta in in g P in 2 -3 S h if t V a iv e 29. S p r in g 1-2 S h if t V a lv e 22. V a lv e 1-2 P rim a r y 1-2 A c c u m u la to r V a lv e S e c, S p r in g F ig . 7 B - C o n tr o l V a lv e A s s e m b ly - E x p lo d e d V ie w 11. Install 2-3 m odulator valve into 2-3 accum ulator bushing and install both parts into valve body bore. 14. Compress bushing against spring and install retaining pin. 12. Install 2-3 valve spring and retaining pin. 15. Install manual valve with detent pin groove to the right. 13. In next bore up, install 1-2 valve train as follows: FORWARD CLUTCH a. All models except CJ and CP, install the 1-2 shift valve, stem end out. Install the 1-2 regulator valve, larger stem end first, 1-2 regulator spring and 1-2 detent valve, open hole first, into the 1-2 m odulator bushing, aligning the spring in the bore of the detent valve. Install these parts into the valve body bore. b. Models CJ and CP install the 1-2 shift valve, stem end out. Install 1-2 m odulator valve, 1-2 m odulator spring, aligning spring in valve. Install the 1-2 m odulator bushing. The procedure for disassembly, inspection, and assembly remains the same with the exception of these changes: Disassembly a. (Model CA) Remove four (4) radial grooved composition-faced, three (3) thin (.0775") flat steel and one ( 1) waved steel clutch plates from forward clutch housing. b. (Models CJ, CM, CP, CT and CZ) Remove five (5) radial grooved composition-faced, four (4) thin (.0775") flat steel and one (1) waved steel clutch plates TRUCK SUPP - O VERH AUL 7A -8 A U T O M A T IC T R A N S M IS S IO N Fig. 10 B —In s ta llin g D e te n t R e g u la to r V a lv e a n d D e te n t V a lv e 4 ■> \ *i ■ ' _______________ Fig. 8B—Installing Compressor Tool to F ront A ccum ulator Piston NOTE: The production built transmissions use a direct clutch piston without a check ball. The forward and direct clutch pistons look almost the same. Make sure the forward clutch piston is identified during disassembly so it will be reassembled into the forward clutch housing. The production built forward clutch piston will be aluminum or stamped steel. Assembly Assembly procedure, step num ber 10 should read: 10. Install forward clutch plates. a. (Model CA) Install one (1) waved steel (plate with "U" notch), four (4) composition and three (3) thin (.0775") flat steel clutch plates, starting with waved plate and alternating composition-faced and steel clutch plates. b. (Models CJ, CM, CP, CT and CZ) Install one (1) waved steel (plate with "U" notch), five (5) composition-faced and four (4) thin (.0775") flat steel clutch plates, starting with waved plate and alternating composition-faced and steel clutch plates. Fig. 9 B - F r o n t A c c u m u la to r A s s e m b ly - E x p lo d e d from the forward clutch housing. c. (Models CG and CR) Remove five (5) radial grooved composition- faced, four (4) thick (.0915") flat steel and one ( 1) waved steel clutch plates from forward clutch housing. d. (Model CL) Remove five (5) radial grooved composition-faced and five (5) thick (.0915") flat steel clutch plates. c. (Models CG and CR) Install one (1) waved steel (plate with "U" notch), five (5) composition and four (4) thick (.0915") flat steel clutch plates, starting with waved plate and alternating composition-faced and steel clutch plates. d. (Model CL) Install five (5) thick (.0915") flat steel and five (5) composition-faced clutch plates, starting with flat steel and alternating composition-faced and flat steel clutch plates. NOTE: The model "CL" forward clutch composition-faced plates are different from the other models. Refer to parts catalog book for correct usage. TRUCK SUPP - O VERHAUL A U T O M A T IC T R A N S M IS S IO N DIRECT CLUTCH AND INTERMEDIATE CLUTCH 7A -9 CHAMFER FOR IDENTIFICATION \ The procedure for disassembly, inspection, and assembly remains the same with the exception of these changes or additions: Disassembly Disassembly procedure, step num ber 4 and 5 should read: 4. Remove direct clutch backing plate. 5. Remove direct clutch plates as follows: a. (Model CA) Remove four (4) composition-faced, and four (4) flat steel clutch plates from the direct clutch housing. b. (Models CG, CJ, CM, CP, CR and CT) Remove five (5) composition-faced and five (5) flat steel clutch plates from the direct clutch housing. DIRECT CLUTCH HOUSING FOR 4 OR 5 PLATE PACK DIRECT CLUTCH HOUSING FOR 6 PLATE CLUTCH PACK F ig . 1 1 B --D ire c t C lu tc h H o u s in g P la te P a ck c. (Models CL and CZ) Remove six (6) composition-faced and six ( 6) flat steel clutch plates from the direct clutch housing. NOTE: The production built transmissions use a direct clutch piston w ithout a check ball. The forward and direct clutch pistons look almost the same. Make sure the direct clutch piston is identified during disassembly so it will be re-assembled into the direct clutch housing. The service replacement direct clutch piston contains a check ball. (Models CL and CZ contain 2 check balls.) The production built direct clutch piston will be aluminum or stamped steel. CHECK BALL DIRECT CLUTCH H O U S IN G Inspection Inspection procedure add steps num ber 6, 7 and 8 which will read: 6 . Inspect clutch piston for cracks. 7. Inspect fourteen (14) release springs for collapsed coils or signs of distortion. NOTE: The 14 direct clutch release springs are not serviced. If one or more of these springs require replacement, discard all of them and install the 16 service direct clutch release springs. 8. Inspect housing for free operation of check ball. Assembly Assembly procedure, caution should read: CAUTION: The direct clutch housing for the CL and CZ models use the 6 plate clutch assembly (Fig. 1IB). Production built transmissions now use a direct clutch housing with a check ball (see Fig. 10B). I f the housing requires replacement and the replacement housing does not contain a check ball, replace the direct clutch piston with the service piston which has a check ball (Models CL and CZ service piston has 2 check balls). EITHER THE DIRECT CLUTCH HOUSING AND/OR THE PISTON MUST CONTAIN A CHECK BALL(S). F ig . 1 2 B - D ir e c t C lu tc h H o u s in g Assembly procedure, step num ber 5, should read: 5. Install fourteen (14) springs into piston leaving two pockets diametrically opposite with no springs. Assembly procedure, step num ber 8, should read: 8. Install direct clutch plates. a. (Model CA) Oil and install four (4) composition-faced, and four (4) flat steel clutch plates starting with a flat steel plate and alternating composition-faced and flat steel clutch plates. b. (Models CG, CJ, CM, CP, C R and CT) Oil and install five (5) composition-faced and five (5) flat steel clutch plates, starting with a flat steel plate and alternating composition-faced and flat steel clutch plates. c. (Models CL and CZ) Oil and install six ( 6) composition-faced and six ( 6) flat steel clutch plates, starting with a flat steel plate and alternating T RUC K S U P P - O V E R H A U L 7 A -1 0 A U T O M A T IC T R A N S M IS S IO N composition-faced and flat steel clutch plates. NOTE: All direct clutch flat steel clutch plates are the thick (.0915") type. The model "CL" direct clutch composition-faced lates are different from the other models. Refer to parts catalog book for correct usage. NOTE: The reaction carrier with the undercut and spacer ring is used optionally and interchangeably with the reaction carrier which does not have an undercut and spacer ring. Assembly procedure, Step num ber 11 should read: 11. Install the interm ediate clutch outer race with a clockwise turning motion. NOTE: Interm ediate roller clutch is not released for the CL and CZ models. The sprag assembly is released for these models. CENTER SUPPORT The procedure for disassembly, inspection and assembly remains the same with the following exception: Assembly Assembly procedure, Step num ber 7, should read: 7. Install four (4) oil seal rings on the center support. NOTE: W hen installing teflon oil seal rings, make sure slit ends are assembled in same relation as cut (Fig. 13B). Also, make sure oil seal rings are seated in ring grooves to prevent damage to rings during re-assembly of m ating parts over rings. Retain with petrolatum. F ig . 1 4 B - ln s p e c tin g S p a c e r R ing FRONT AND REAR BANDS, SUPPORT TO CASE SPACER Inspection 1. Inspect lining for cracks, flaking, burning, or looseness. 2. Inspect bands for cracks or distortion. 3. Inspect end for damage at anchor lugs or apply lugs. 4. Inspect support to case spacer for burrs or raised edges, if present remove with stone or fine abrasive. CASE EXTENSION (EXCEPT CL MODEL) Inspection The procedure for inspection remains the same with the following exception: Inspection procedure, Step num ber 1, should read: 1. Inspect bushing for excessive wear or damage. If replacement is necessary, remove rear seal and with extension housing properly supported, remove bushing as follows: REACTION CARRIER, ROLLER CLUTCH AND OUTPUT CARRIER ASSEMBLY The procedure for inspection remains the same with the following addition: Inspection procedure, step num ber 1, should read: 1. If the reaction carrier has a spacer ring in an undercut at the bottom of the roller cam ramps, inspect it for damage (Fig. 14B). a. (All except CA and CB Models) Using Tool J-2 1465-17 with D river H andle J-8092, drive or press replacement bushing into place, flush to .010 below oil seal counter bore area. Stake bushing, using tool J-2 1465-10. Stake marks to be in bushing lubrication grooves. b. (CA Model) Using Tool J-2 1424-9 with Driver Handle J-8092, drive or press replacement bushing into place flush to .010 below oil seal counter bore area. Stake bushing, using tool J-2 1465-10 (or J-8400-22). Stake marks to be in bushing lubrication grooves. TRUC K SUP P ■ O V E R H A U L A U T O M A T IC T R A N S M IS S IO N CASE EXTENSION-CL MODEL (Fig. 15B) 7 A -1 1 Inspection Inspection procedure, step num ber 4 and 5 should read: Inspection 1. Inspect seal (case extension to case) groove for amage. 2. Inspect for cracks, or porosity. 3. Inspect dowel pin in rear face for damage. 4. Inspect oil seal for damage. If replacement is required, proceed as follows: a. Pry oil seal from extension. b. Apply non-hardening sealer to outside of new oil seal, and install oil seal into case extension using tool (J-24057). 5. Inspect ball bearing assemblies. If they are damaged, or if they require cleaning, proceed as follows: 4. On model CL inspect studs for thread damage, and make sure they are tight. NOTE: The two (2) studs at 9 o’clock and 11 o’clock (when viewed from the rear of case and transmission in vehicle) are approximately 1/4" longer than the other four (4) studs. These two longer studs are required to accommodate the parking brake actuating cable bracket. 5. Inspect interm ediate clutch driven plate lugs for age or brinneling. NOTE: If the case assembly requires replacement, remove the nameplate from the old case and re-install it on the new case, using the truss head nameplate ' attaching screw that is serviced with the case. a. Remove rear seal. REAR UNIT b. Remove snap ring. The procedure for assembly remains the same with the following addition: c. Remove ball bearings and bearing spacer, using a brass rod on the outside race of bearing. An arbor press can be used if tool to press bearing out is located on outer race of bearing. CAUTION: D O N O T locate against inner race o r balls. d. Install ball bearing assembly and spacer, bearing first. Assembly 11. Install reaction carrier to output carrier metal or non-metal thrust washer with tabs facing down in pockets of output carrier and retain with petrolatum. NOTE: The production built transmissions use a non-metal washer here. However, the service replacement washer is made of metal. e. Install ball bearing assembly and snap ring. ASSEMBLY OF UNITS TO TRANSMISSION f. Install new rear oil seal. CASE CASE ASSEMBLY The procedure for inspection remains the same with the following addition: The procedure for assembly remains the same with the following exception: Assembly procedure, Step num ber 12, should read: 12. Install interm ediate clutch plates. REAR OIL SEAL BALL BEARINGS a. (All models except CL and CZ) Lubricate with transmission oil two (2) flat steel and one ( 1) waved steel plates and three (3) composition-faced intermediate clutch plates and install, starting with waved steel plate and alternating composition-faced and flat steel plates (fig. 16B). b. (Models CL and CZ) Lubricate with transmission oil three (3) flat steel and three (3) composition-faced intermediate clutch plates and install, starting with flat steel and alternating composition-faced and flat steel plates (Fig. 16B). NOTE: The models CL and CZ intermediate composition-faced plates are different from the other models. Refer to parts catalog for correct usage. SNAP RING BEARING SPACER CASE EXTENSION CASE EXTENSION ASSEMBLY 1. Install new case extension housing to case gasket on extension housing. Model CL uses a seal between the extension housing and case extension. F ig . 1 5 B - M o d e l C L C a s e E x te n s io n 2. A ttach extension housing to case using attaching bolts an d /o r studs. Torque bolts to 20-25 ft. lbs. TRUCK SUPP - O VERH AUL 7 A -1 2 A U T O M A T IC T R A N S M IS S IO N F ig . 1 6 B —In s ta llin g In te r m e d ia te B a c k in g P la te a n d C lu tc h P la te s NOTE: Models CA, CG and CR use two (2) studs at 5 o’clock and 7 o’clock positions (when viewed from the rear of case and transmission in vehicle). These studs are for the installation of the catalytic converter. Torque the studs to 20-25 ft. lbs. 3. If necessary, install a new seal as follows: a. (All except CA and CL Models) use a non-hardening sealer on outside of seal body; and using Tool J-2 1359, drive seal in place (fig. 17B). F ig . 1 7 B —In s ta llin g E x te n s io n O il S e a l (T y p ic a l) MODULATOR VALVE AND VACUU M MODULATOR Installation b. (Model CL) use a non-hardening sealer on outside of seal body; and using Tool J-24057 drive seal in place (fig. 17B). c. (Model CA) use a non-hardening sealer on outside of seal body; and using Tool J-2 1426, drive seal in place (fig. 17B). 1. Install m odulator valve into case, stem end out. 2. Install "O" ring seal on vacuum modulator. 3. Install vacuum m odulator into case. NOTE: Models CA and CZ use a modulator that is CHECK BALLS, CONTROL VALVE SPACER different than the m odulator used on the other models. PLATE AND GASKET, DETENT SOLENOID, Refer to parts catalog book for correct usage. FRONT SERVO ASSEMBLY, AND ELECTRICAL CONNECTOR 4. Install m odulator retainer and attaching bolt. Torque bolt 18 ft. lbs. CONVERTER ASSEMBLY The procedure for assembly remains the same with the following additions: Installation Assembly With the transmission in cradle or portable jack, install the Assembly procedure, steps num ber 3 and 4 should read: converter assembly into the pum p assembly making certain 3. Install control valve spacer plate-to-case gasket (gasket that the converter hub drive slots are fully engaged with the with extension for detent solenoid and a "C" near front servo location). pump drive gear tangs and the converter installed fully towards the rear of the transmission. 4. Install control valve spacer plate and control valve to spacer plate gasket (gasket identified with a a " VB" near NOTE: The converter used in the CL, CM, CT, and front servo). CZ models has six ( 6) m ounting lugs. T R U C K SUP P - O V E R H A U L S E C TIO N 9 STEERING IN D E X Overhaul O perations........................................................................... 9-1 Power Steering Pum p....................................................................... 9-1 Power Steering G e a r.......................................................................... 9-1 Special T o o ls........................................................................................... 9-6 OVERHAUL OPERATIONS Fig. 1—Power S te e rin g P u m p P ulley R em oval All service overhaul procedures for 1976 Light Duty Truck are identical to the procedures outlined in the 1974 Overhaul Manual, Section 9, with the exception of the following procedures. Fig. 2 —Pow er S te e rin g P u m p P u lle y In s ta lla tio n 20. Install pump pulley by inserting tool J-25033 through pulley hub and threading the bolt into the power steering pulley shaft as shown in Figure 2. NOTE: Pulley must be flush with end of shaft. POWER STEERING PUMP CAUTION: D O N O T hammer on pum p shaft. Use Disassembly special tools to prevent possible damage to internal pump components. Take care to avoid nicks o r scratches on pum p pulley shaft. 1. Remove pump pulley by using tool J-25034 as shown in Figure 1. NOTE: Steps 2-15 are identical to the 1974 Overhaul Manual, Section 9, Page 9-8. Assembly NOTE: Steps 1-19 are identical to the 1974 Overhaul Manual, Section 9, Pages 9-11 and 9-12. POWER STEERING GEAR (INTEGRAL) Adjuster Plug Disassembly 1. If the oil seal ON LY is to be replaced, and not the needle bearing, install the adjuster plug (Fig. 3) loosely in the gear housing. Remove the retaining ring with Internal Pliers J-4245. W ith a screwdriver, pry the dust seal and oil seal from the bore of the adjuster plug being careful not to score the seal bore. Discard the oil seal. TRUC K SUP P - O V E R H A U L 9-2 STEERING i 1. 2. 3. 4. 5. 6, Ring, Retaining Seal, Stub Shaft Dust 7. Race, Upper Bearing (Large) Seal, Stub Shaft 8. Bearing, Upper Thrust Bearing, Needle 9. Race, Upper Thrust Bearing (Sm all) Plug, Adjuster 10, Spacer, Thrust Bearing Seal, " 0 ” Ring (Adjuster) 11, Retainer, Bearing 10 11 *r 4 V 4 ; 1 % ** Fig. 3 ~ A d ju s te r P lu g 6. Inspect thrust bearing rollers and thrust races for wear, pitting or scoring. If any of these conditions exist, replace the bearing, thrust races, spacer, and retainer. Assembly 1. If the needle bearing was removed, place new needle bearing over Tool J-8524-1 and J-7079-2, with the bearing m anufacturer’s identification against the tool, and drive the bearing into the adjuster plug until the tool bottoms in the housing (Fig. 6). CAUTION: Place a block o f wood under the adjuster plug to protect it during drivin g o f the bearing. F ig . 4 - R e m o v in g R e ta in e r 2. If the thrust bearing O N LY is to be removed, pry the thrust bearing retainer at the two raised areas with a small screwdriver (Fig. 4). Remove the spacer, thrust bearing race, thrust bearing and the flanged thrust bearing race. 2. Place dust seal and a new stub shaft seal on Tool J-8524-1 (face of seal with part number against tool), Lubricate seal with Power Steering Fluid and drive or press seal into adjuster plug until seated (Fig. 7). W hen properly installed, the stub shaft seal under the dust seal and the inner dust seal lip is not bottomed on the stub shaft assembly. 3. Install retaining ring with Internal Pliers J-4245. 3. If the needle bearing is to be replaced, remove the retaining ring using Internal Pliers J-4245. Remove thrust bearing as outlined in Step 2 above. Drive needle bearing, dust seal and oil seal from adjuster plug using Bearing Remover J-8524-2 and Driver J-7079-2 as shown in Fig. 5. Discard the seals. 4. Lubricate the thrust bearing assembly with Power Steering Fluid. Place the flanged thrust bearing race on the adjuster plug hub, then install the thrust bearing, small bearing race (flanged side up) and spacer (grooves of spacer away from bearing race). 4. Wash all parts in clean solvent and dry parts with compressed air. 5. Install bearing retainer on the adjuster plug by carefully tapping on the flat surace of the retainer (Fig. 8). 5. Inspect thrust bearing spacer for wear or cracks. Replace if damaged. CAUTION: The projections must n ot extend beyond the spacer when the retainer is sealed to prevent TRUCK SUPP - O VERHAUL STEERING 9-3 BEARING W ITH ID EN TIFIC ATIO N T O W A R D TO O L F ig . 6 —I n s t a llin g B e a rin g F ig . 5 --R e m o v in g B e a r in g a n d S e a l interference with valve body. The spacer must be free to rotate. P ow er S teering Gear A d ju s tm e n t Procedure Adjustm ent of the steering gear in the vehicle is discouraged because of the difficulty encountered in adjusting the worm thrust bearing preload and the confusing effects of the hydraulic fluid in the gear. Since a gear adjustm ent is made only as a correction and not as a periodic adjustment, it is better to take the extra time and make the adjustment correctly the first time. Since a handling stability com plaint can be caused by improperly adjusted worm bearings as well as an improper gear over-center adjustment, it is necessary that the steering gear assembly be removed from the vehicle and both thrust bearing and over-center preload be checked and corrected as necessary. An in-vehicle check of the steering gear will not pin-point a thrust bearing looseness. Thru st Bearing A d ju stm e n t If a gear is known to contain the new thrust bearing parts, thrust bearing adjustm ent in service is simplified. Recommended procedure: 1. Drain power steering fluid from gear by rotating the stub shaft full travel in both directions several times. 2. Loosen and remove adjuster plug lock nut (Fig. 9 and 10). 3. Using spanner wrench J-7624, turn the adjuster plug in (clockwise) until the plug and thrust bearings are firmly bottomed approximately 20 foot-pounds (Fig. 11). 4. M ark the housing even with one of the holes in the face of the adjuster plug (Fig. 12). 5. Measure back (CCW direction) 1/2 inch (12.5 millimetres) and place a second mark on the housing (Fig. 13). 6. Turn adjuster plug counterclockwise until the hole in the face of the adjuster plug, which was even with the first m ark is in line with second m ark (Fig. 14). 7. Tighten lock nut securely. Hold (or have held) adjuster plug to m aintain alignment of hole with m ark (Fig. 15). TR U C K SUP P - O V E R H A U L 9-4 STEERING J -7 0 7 9 - 2 F ig . 7 - -In s ta IIin g A d ju s te r P lu g S e a l F ig . 9 - L o o s e n in g L o c k N u t F ig . 1 0 --F te m o vin g L o c k N u t F ig . 8 - -In s ta llin g R e ta in e r TRUC K S U P P - O V E R H A U L STEERING 9-5 Fig. 1 3 --M e a s u re B a c k a n d R e m a rk H o u s in g TRUC K SUP P - O V E R H A U L 9-6 STEERING 2 1 1. PUMP PULLEY REMOVER J-25034 2. PUMP PULLEY INSTALLER J-25033 F ig . 1 6 --S p e c ia l T o o ls TR U C K S U P P - O V E R H A U L S P E C IF IC A T IO N S H E A T IN G AND A IR C O N D I T IO N I N G SECTION 1A HEATER V o lts A m p s. (C o ld ) RPM (Cold) Blower Motor C-K M odels............. 13.5 G M o d e ls................ 13.5 6.25 Max. 7.1 Max. 4 2550 2950 2850 3250 Min. Max. Min. Max. Fuses C-K M odels........................................................................ 20 Amp. G M o d e ls...........................................................................20 Amp. System Capacities Refrigerant 12 C-K Four-Season System ...................... 3 lbs. 12 oz. C-K-G Overhead S y s te m s ........................ 5 lbs. 4 oz. G Model C60 S y s te m ................................ 3 lbs. Motor Home Chassis U n i t ........................ 3 lbs. 4 oz. 525 Viscosity Compressor Oil 6 Cylinder A x ia l.............................. 10.5 Fluid oz. 4 Cylinder Radial ..................................... 6.0 Fluid oz. Overhead S y stem s................................................ 13 oz. Torque Specifications A U X IL IA R Y HEATER Volts Blower Motor . . . . 13.5 Amps. (Cold) 9.6 Max. RPM (Cold) 2700 Min. A IR C O N D ITIO N IN G Compressor Make ................................................................................ Frigidaire T y p e ..................................................................... 6 Cylinder Axial 4 Cylinder Radial Displacement 6 Cylinder A x ia l.....................................................12.6 Cu. In. 5 Cylinder R a d ia l...................................................10.0 Cu. In. R o ta tio n ............................................................................Clockwise Volts Amps. (Cold) RPM (Cold) Compressor Suction and Discharge Connector B o l t .............................................. 22 ft. lbs. Rear Head to Shell Stud Nuts (6 Cyl.) ......... 23 ft. lbs. Shaft Mounting Nut (6 C y l.)............................ 20 ft. lbs. Shaft Mounting Nut (4 C y l.) ....................... 8—12 ft. lbs. High Pressure Relief Valve (6 C y l.) ................ 12 ft. lbs. Oil Charge Screw (6 Cyl.) ................................ 14 ft. Ibs. Air Gap on Clutch (6 C y l .) ........................ 022 to .057 in. Compressor Mounting Bracket Bolts (6 Cyl.) ............................................................ 20 ft. lbs. Front Bracket to Compressor Bolts (6 C y l.) ............................................................ 20 ft. lbs. Compressor Mounting Bracket Bolts (4 C y l.) ............................................................ 18 ft. lbs. Belt T e n s io n ..........................................See Tune-Up Chart Fuses Fuse Block— Blower Motor C-K Four Season . . 12.0 C-K-G Overhead, G Floor and Motor Home U n its...................12.0 12.8 Max. 13.7 Max. 3400 Min. C-K Systems . . . . .........................................25 Amp. Motor Home Chassis U nit.............................20 Amp. 3400 Min. In-LineC-K Four-Season S y ste m s ..............................30 Amp. C-K Overhead System .................................. Motor Home Chassis U n it................................... None Compressor Clutch Coil Ohms (at 8 0 ° F ) ........................................................ 3.70 Amps, (at 8 0 ° F ) ......................................3.33 @ 12 volts Circuit Breaker G Model System s..................................... .. 35 Amp. TR U CK SU PP — SPECS SPECIFICATIONS 2 BODY SECTION IB C A N D K MODELS FRONT END Windshield Wiper Linkage to Plenum ........................25 in. lb. Sunshade S u p p o r t...........................................................20 in. lb. Inside Rear View Mirror to B rack et............................. 45 in. lb. Outside Rear View Mirror to Door Panel — Base M ir r o r ............................................................. 25 in. lb. West Coast M irror-Lower Bracket to Door . . . 20 in. lb. —Upper Bracket to Door. . . . 45 in. lb. END GATE (06) Hinges—Hinge to B o d y ...................................................35 ft. lb. —Hinge to End Gate............................................. 20 ft. lb. Support Cable B o lts ........................................................ 25 ft. lb. Torque R od—Silencer B racket..................................... 40 in. lb. —End Support Bracket............................. 90 in. lb. Latch Assembly to End G a t e ........................................ 20 ft. lb. Latch Remote Control Assembly to End Gate . . . . 40 in. lb. Access Cover ...................................................................18 in. lb. Outside Handle ............................................................. 55 in. lb. Glass C h an n el...................................................................45 in. lb. DOORS Window Regulator Assembly to Door P a n e l............. 85 in. lb. Remote Control Door Lock to Door P a n e l................ 45 in. lb. Lock Striker to Body P illa r ........................................... 45 ft. lb. Outside Door Handle........................................................ 85 in. lb. Inside Door H a n d le ........................................................ 85 in. lb. Hinges to Body and D o o r ............................................. 35 ft. lb. Front Door—Window Run C hannel-to-D oor 8 5 in. lb. Front Door—Ventilator Assembly Top Vent S c re w ..................................................... 18 in. lb. Side Vent Screws and S p a c e rs............................. 25 in. lb. Lower Vent Channel B o l t s ...................................40 in. lb. Side Rear Door—Run Channel Front Upper to D o o r............................................. 40 in. lb. Rear-Upper to Door ............................................. 20 in. lb. Front and Rear Lower to Door............................. 85 in. lb. Lock Lever to Door ............................................. 85 in. lb. Rear Door—Lock Striker (06) ..................................... 95 in. lb. Rear Door—Latch L.H. and R.H. to Door (06) . . . . 85 in. lb. Rear Door—Latch Control Assembly to Door (06) —Upper A ssem b ly ........................................85 in. lb. —Lower A ssem bly........................................ 90 in. lb. Rear Door—Weatherstrip L.H. ( 0 6 ) ............................. 18 in. lb. -C heck Arm - Strap to D o o r ......................................... 45 in. lb. Bracket to Body 4 5 in .lb . END GATE (14)(16) Hinges—Body Half and Gate H a l f ................................ 35 ft. lb. Support Assembly—Body to End G a te ........................ 25 ft. lb. Torque Rod—Retainer Assembly...................................85 in. lb. —Anchor A sse m b ly ...................................18 ft. lb. Latch Assembly to End G a t e ........................................ 85 in. lb. Latch Control Assembly to End Gate ........................40 in. lb. Access C over..................................................................... 18 in. lb. Handle to Latch Control A ssem bly ............................. 45 in. lb. Glass Channel Assembly to End Gate ........................ 85 in. lb. Cap Assembly to Channel Assembly............................. 40 in. lb. Striker—Body Mounted ................................................ 18 ft. lb. TA ILG A TE (03, 6 3 -w ith E63) Trunnion A ssem b ly ........................................................ 18 ft. lb. Linkage and Striker Assembly—Support ...................25 in. lb. T A IL G A T E (0 3, 6 3 - w i t h E 62) Trunnion A ssem b ly ........................................................ 35 ft. lb. Chain Support Assembly ............................................. 90 in. lb. SEATS Front Bench Seat (03 ,0 6 ,6 3 ) Adjuster-to-Seat ................................................ 155 in. lb. A djuster-to-F loor...................................................25 ft. lb. Front Bucket Type (14, 03) Driver Adjuster-to-Seat............................................. 18 ft. lb. Adjuster-to-Floor ........................................ 25 ft. lb. Passenger (03) Support-to-Seat..............................................18 ft. lb. Support-to-Floor (F ro n t)............................. 25 ft. lb. Support-to-Floor ( R e a r ) ............................. 40 ft. lb. Passenger (14) Latch Support-to-Seat (Rear) ...................18 ft. lb. Striker-to-Floor (Rear) ............................. 25 ft. lb. Support (Upper)-to-Seat (Front) ..............18 ft. lb. Support (Lower)-to-Floor (F ro n t) ............. 25 ft. lb. Support (Upper)-to-Support (Lower) . . . . 18 ft. lb. Rear Bench (06, 14) S u p p o rt-to -S ea t......................................................18 ft. lb. Support-to-Floor ...................................................40 ft. lb. Rear Bench (63) S u p p o rt-to -S e at...................................................150 in. lb. Support-to-Floor ................................................ 18 in. lb. Folding Rear Seat (06) Support A sm -to-F loor........................................ 150 in. lb. Seat-to-Support A s m ..............................................18 in. lb. TR U CK SU PP — SPECS SPECIFICATIONS 3 BODY MOUNTING (C-K M ODELS)-FT. LBS. Model (03) (06) (1 4 )(1 6 ) (63) #1 #2 45 55 55 55 45 35 45 35 #3 — 35 55 #4 — 35 35 - #5 #6 — — — 35 — — - - G MODELS MIRRORS A N D SUNSHADE S LID IN G SIDE DOOR Inside Rear View Mirror to Bracket ........................15 in. lb. Outside Rear View Mirror to D oor Panel 25 in. lb. Sunshade Support to Header P a n e l............................. 15 in. lb. Remote Control (front latch) to D o o r ........................90 in. lb. Rear Latch to D o o r ........................................................ 90 in. lb. Rear Plate to Door ........................................................ 90 in. lb. Lower Front Roller and Roller Support Support-to-Door ...................................................24 ft. lb. Support to Roller Bracket ...................................24 ft. lb. Roller to Roller B racket........................................ 20 ft. lb. Catch to Roller B ra c k e t...................................45 in. lb. Upper Front Roller Bracket Bracket to D o o r ..................................................... 24 ft. lb. Roller to B r a c k e t...................................................20 ft. lb. Upper Left Hinge (Door Half) Hinge to D o o r ........................................................ 25 ft. lb. U pper Left Hinge (Body Half) Roller to H inge........................................................ 20 ft. lb. Guide Block to Hinge............................................. 40 in. lb. Lever Arm-to-Hinge Retaining Nut ................ 120 in. lb. Lever Retaining S crew ........................................... 40 in. lb. Striker to B ody........................................................ 20 ft. lb. Rear Striker Bolt (Body M o u n te d )............................. 45 ft. lb. Front Striker Retaining Screws (Body Mounted) . . 90 in. lb. SIDE WINDOW (SWINGOUT) Latch to B ody.................................................................. 40 in. lb. Latch to G lass.................................................................. 40 in. lb. Hinge to B ody.................................................................. 50 in. lb. FRONT SIDE DOORS Door H in g e s..................................................................... 30 ft. lb, Door Hinge Access Hole Cover ...................................18 in. lb. Door Lock S tr ik e r .......................................................... 45 ft. lb. Door Lock to D o o r ........................................................20 ft. lb. Outside Door H a n d le ..................................................... 45 in. lb. SEATS REAR DOOR Hinge Strap to D o o r........................................................45 Hinge Strap Bracket to B o d y ........................................45 Hinge (to body and d o o r ) ............................................. 30 Remote Control Retaining Screws ............................. 85 Latch-to-Door Retaining S crew s...................................90 Door Strikers-to-Body ...................................................90 Outside Door H a n d le ..................................................... 45 in. lb. in. lb. ft. lb. in. lb. in. lb. in. lb. in. lb. Seat Belt to S e a t ............................................................. 37 ft. lb. Passenger and Drivers Seat to Adjuster (Mounting B r a c k e t) ................ 18 ft. lb. Seat to R i s e r ...........................................................18 ft. lb. Seat R iser-to-F loor................................................ 50 ft. lb. Bench Seats Seat to Seat S u p p o r t............................................. 18 ft. lb. Seat Support to Floor C lam ps............................. 40 ft. lb. TR U CK SUPP — SPECS SPECIFICATIONS 4 FR O N T S U S P E N S IO N SECTION 3 WHEEL ALIGNMENT SPECIFICATIONS CA STER * D IM E N SIO N “A ’ IN IN C HES* 2 1/ 2 " M O D ELS 2 3 /4 " 3" + 2° CIO + 1 1/ 2 ° + 1 1/4° C20.C 30 + 1° 3 1 /4 " + 3 /4 ° K 10.K 20 + 1/ 2 ° 3 3 /4 " 4" 4 1 /4 " 4 3 /4 " 5" + 1° + 3 /4 ° + 1/ 2 ° + 1 /4 C 0° - 1/ 2 ° -1 /4 ° - 1/ 2 ° - 3 /4 ° - 1° + 1/4° 0° 4 1 /2 " + 4° (NO A D JU S T M E N T P R O V IS IO N ) + 2° G 10,G 20,G 30 + 2 1/4 ° P 10.P 20.P 30 + 2 1/ 2 ° + 2 1/4 ° M O TO R HOM E 3 1 /2 " + 1 1/ 2 ° + 1 1 /4 ° (3 2 ) +5 3 /4 +5 1/2 + 1 1/ 2 ° + 1 1/4 ° + 2° +5 + 1° + 1 3 /4 ° + 1 1/ 2 ° +5 +4 1 /2 + 3 /4 ° + 1/ 2 ° + 1/4 ° 0° - 1 /4 ° - 1/ 2 ° + 1° + 3 /4 ° + 1/ 2 ° + 1 /4 ° 0° - 1 /4 ° +4 1/4 +4 +4 +3 1 /2 +3 1/4 +3 I CAM BER C10.C 20.C 30 + 1 /4 U K 10.K 20 + 1 1/2 ° N O A D JU S T M E N T P R O V IS IO N G I0 .G 2 0 .G 3 0 + 1/4° C am b er o n P -T ruck is d e p e n d e n t o n dim en sio n ‘A ’, as ex p lain ed o n page 3-15 o f th e 1974 L ig h t D u ty T ru c k S ervice M anual. A fte r m easuring d im en sio n ‘A ’ set cam b er as follow s: 2 1/ 2 " 2 3 /4 " 3" 3 1 /4 " 3 1 /2 " 3 3 /4 " 4" 4 1 /4 " 4 1 /2 " 5" 5 1 /4 " 5 1 /2 " P10 0 0 + 1 /4 ° + 1/4 ° + 1 /4 ° + 1/4° + 1/4 ° 0° 0° 0° - 1 /4 ° - 1/ 2 ° -3 /4 ° P 20.P 30 0 0 + 1 /4 ° + 1/4 ° + 1 /4 ° + 1/4° + 1/4 ° + 1 /4 ° 0° 0° -1 /4 ° - 1/ 2 ° -3 /4 ° 0 0 + 1 /4 ° + 1/4 ° + 1/4° + 1 /4 ° 0° - 1/ 2 ° -3 /4 ° - 1° M O TO R HOM E (3 2 ) T O E -IN C 10,C 20,C 30 K 10.K 20 0 3 /1 6 " P 10.P 20.P 30 3 /1 6 " -1 /4 ° R E PA IR TARGET P E R IO D IC M O TO R V E H IC LE IN S P E C T IO N ± 1° ± 1/ 2 ° -H 5/16” R E S E T T IN G O CN) MOTORHOME W ARRANTY C H E C K IN G CA STER (3 2 ) 0° A L IG N M E N T T O L E R A N C E S 3 /1 6 " G 1 0 .G 2 0 .G 3 0 P30 0° 4 3 /4 " CA M BER ± 3 /4 ° ± 1/ 2 ° ±1 1/ 2 ° T O E -IN ± 1/ 8 " ± 1 /1 6 " ± 3 /8 ° *R efer to page 3-15 o f the 1974 L ight D uty Truck Service M anual. TR U CK SU PP — SPECS SPECIFICATIONS 5 FRONT SUSPENSION BOLT TORQUE (Ft. Lbs.) $ 030 CP-10 CP-20-30 K-AII Lower Control Arm Shaft U-Bolt 85 85 — 45 85 Upper Control Arm Shaft Nuts 70 105 — 70 105 Control Arm Rubber Bushings 140 Upper Control Arm Bushing Steel Lower Control Arm Bushing Steel - — $$ New Used 190 115 $$ New Used 280 130 - w/Spacer 190 No Spacer 115 — w/Spacer 280 No Spacer 130 w/Spacer 280 No Spacer 130 *50 **90 **1 00 Lower Ball Joint Nut **90 **90 65 100 Crossmember to Bottom Rail C ro s s m e m b e r B ra k e S u p p o r t S tr u ts 140 w/Spacer 160 No Spacer 95 Upper Ball Joint Nut Crossmember to Side Rail G-10-20 *50 **90 ***80 **90 **90 65 — 65 65 100 — 100 100 60 60 Stabilizer Bar to Control Arm 25 25 ANCHOR _ 130 PLATE Stabilizer Bar to Frame 25 25 .5 5 25 Shock Absorber Upper End 140 140 65 75 Shock Absorber Lower End 60 60 65 75 Brake Splash Shield to Knuckle 120 In Lbs. 120 - Wheel Bearing Adjustment Zero Wheel Bearing Preload Wheel Bearing End Movement Caliper Mounting Bolt .0 0 1 In. L bs. 120 - Inner # - 35 Outer -50 Zero - .0 0 5 ” .0 0 1 35 In. Lbs. 25 120 l a Lbs. - Zero Zero .001 - .010" .001 - .005 35 35 35 - .0 0 5 ” Spring - Front Eye Bolt - - 90 - Spring - Rear Eye Bolt — — 50 - Spring - To Rear Shackle Bolt — — 50 - Spring - To Axle U-Bolt - - 150 - — 25 — Suspension Bumper 15 15 25 15 Stabilizer to Spring Plate — — 130 - S p rin g * *■* *** # $ $$ - F r o n t S u p p o r t t o F ra m e Plus additional torque to align cotter pin. Not to exceed 90 ft. lbs. maximum. Plus additional torque to align cotter pin. Not to exceed 130 ft. lbs. maximum. pius additional torque to align cotter pin. Back nut off to align cotter pin at nearest slot. All specifications are given in foot pounds of Torque unless indicated otherwise. CIO, G10-20 Rubber Bushings; C20-30, G30, P I0-30 Steel Bushings. F O U R W H EE L D R IV E Axle Bolt Torques (Ft. Lbs.) 5500# (Dana) Gear Backlash Preferred .004” - .009” Carrier Cover Min. and Max. .004” - .009” Ring Gear New Pinion Bearing Preload 20-40 in. lbs. Differential Bearing Caps Used Pinion Bearing Preload 10-20 in. lbs. Filler Plugs 35 110 85 10 Drive Pinion Nut 255 Brake - Backing Plate 35 Axle Shaft To Hub Bolts 60 m ueK supp — specs SPECIFICATIONS 6 REAR SUSPENSION S E C TIO N 4 REAR WHEEL BEARING ADJUSTMENT SPECIFICATION Ring Gear Size B earing Adjusting Nut Torque* Adjusting Nut Back-off* Outer Locknut Torque R esulting Bearing Adjustment Type of B earing 10-1/2” and 9-3/4” 50 Ft. Lbs. ** 65 Ft. -Lbs. .001 to .010 End Play Tapered R oller 1 2 - 1 /4M 90 Ft. Lbs. 250 Ft. Lbs. Slight P reloaded B a rrel R oller 1 /8 * ** B ack-off nut and retighten to 35 Ft. Lbs. then, back-off nut 1 /4 turn. * With wheel rotating. U N IVE R SA L J O IN T A T T A C H M E N T T O R Q U E S PE C IFIC ATIO N S Strap A ttachm ents “ \ J” 15 Ft. Lbs. Bolt A ttachm ent................... ... . . 20 Ft„ Lbs. Ring G ear Size L ubricant C apacity 8 -1 /2 ” 4.2 Pints 8-7 /8 ” 3.5 Pints C hevrolet 10-1/2" 5.4 Pints Dana 10-1/2" 7.2 P ints Dana 9-3/4 12-1/4" 6.0 Pints 14.0 P ints M in . a n d M a x . — Used C hevrolet 10-1/2" 12-1/4” 10-1/2” T_ Dana 9-3/4” 10 18 10 2 0 ”# 2 0 ”# — — — .005".008" .004".009" .005".008" .005".008" D ifferential Pinion Lock .0 0 3 ” .0 1 0 ” .003".010" .004".009" .003".012" .003".012" D rive Pinion Nut — * * 220 D ifferential C arrier to Axle Housing — — - 85 D ifferential Bearing Adjusting Lock — — 20 15 Pinion Bearing Cage To C arrier — — 65 165 Thrust Pad Lock Nut — — - 135 35 105 105 155 — 115 115 15 15-30 15-30 2040 25-35 5-10 10-20 5-15 5-10 | B olt To rq u es (Ft. Lbs.) A C arrier Cover 18 OC .0 0 5 ” .0 0 8 ” P inion B e arin g P r e l o a d (In. L b s . ) — New 25 Csl F iller Plugs G ear B acklash P referred Bolt Torques (Ft. Lbs.) a 8 -7 /8 " S® 12-1/4" 1 OC C h e v ro le t (N d 3 Q 10-1/2" 8 -7 /8 " DIFFERENTIAL S P E C IF IC A T IO N S 20 ”# 2 0 ”# 35”# 30”# — Ring Gear 80 50 110 130 105 Brake - Backing Plate D ifferential Bearing Caps 55 55 85 135 205 Axle Shaft To Hub Bolts A Except where noted otherwise. 35 ♦Torque as necessary to obtain correct preload. TR U CK SU PP — SPECS SPECIFICATIONS 7 TORQUE SPECIFICATIONS (FT. LBS.) (C O N T ’D .) Spring-to-Axle “U” Bolt Nuts Leaf Spring —Front Bushing Bolt 140 P G C-K G 10 G20 G30 120 120 150 P10 P20 P30 140 140 170 (Exc. w /3 /4 ” Bolt) 200 (W /3/4” Bolt) 90 90/135* 90 90 (G 3 1 6 .. .90) 90/135* (G 3 1 6 .. .90) 90 Shock Absorber —Upper Attachment 140 75 P10 25 P20 140 P30 50 —Lower Attachment 115 75 115 —Rear Shackle Bolt Propeller Shaft To Rear Axle (Strap) To Rear Axle (“U” Bolt) Bearing Support-to-Hanger Hanger-to-Frame 12-17 18-22 20-30 40-50 Rear Stabilizer-to-Anchor Plate 20-30 12-17 18-22 20-30 — 12-17 18-22 20-30 20-30 * 90 Ft. Lbs. when tightening the nut. 135 Ft. Lbs. when tightening the bolt. TR U CK SUPP — SPECS SPECIFICATIONS 8 BRAKES S ECTIO N 5 TO R Q U E S P E C IFIC A T IO N S IfC C M a ste r C y lin d e r - to D ash or B o o s te r B o o ste r to D ash o r Fram e C o m b in a tio n V a lv e - M o u n tin g B o lts - B ra c k e t to F ram e C a lip e r - M o u n tin g B olt - S u p p o rt P late to K n u c k le B rake P edal 150 in. lbs. 25 ft. lb s . 25 ft. lb s . 115 in. lib s . - - 35 ft. lb s . 140 in . lb s . - B ra c k e t/to D ash 25 ft. lb s . 25 ft. IbS. - B ra c k e t to I . P . 25 in . lb s . 25 in . lb s . - P iv o t B o lt N ut 25 ft. lb s . 25 ft. Ib s. - S le e v e to B ra c k e t - S to p la m p S w itc h B ra c k e t - P ush Rod to P edal - P ush Rod A d ju s tin g N ut P a rkinq B rake - 17 ft. Ibs. 17 ft. Ib s. 25 ft. Ib s. 25 ft. Ib s . 150 in . Ib s. 25 ft. Ib s. 25 ft. lb s . - - - - 25 ft. - P G 4 5 ft. Ib s. 25 ft. Ibs. - 2 5 ft. Ib s. - - 2 2 ft. Ib s. — 100 in . Ibs. 100 in . Ibs. to I .P . , K ick P anel or F lo orpa n 150 in . lb s . 150 in . Ib s. 100 in . Ibs. C a b le C lip s - S c re w s 150 in . lb s . - 100 in . Ib s ,v to D ash - - B o lts J - - - 100 in lb s . - Ib s. 100 in . Ib s. - 18 ft. Ib s. P ro p s h a ft P arking B rake - A d ju s tin g N ut 18 ft. Ib s. 150 in . Ib s. 55 in . Ibs. 30 ft. Ib s. - - - 20 ft. Ib s. - C a b le C lip to Fram e - - - 150 in . Ibs. - C a b le C lip to D ash - - - 55 in . Ibs. - B ra c k e t to T ra n s . - - - 20 ft. Ib s . - F la n g e P la te - - - 30 ft. Ibs. - D rum - - - 80 ft. Ib s. Ib s. - C a b le C lip to T ra n s . B rk t. W hee l C y lin d e r to F la nge P la te B o lt R ear B rake H ose B ra ke Lin e - 140 ft. lb s . to C a lip e r 22 ft. lb s . - to Fram e N ut 58 in . lb s . - B ra c k e t B o lt 150 in . Ib s. 150 in . - to A x le B ra c k e t 150 in . lb s . 150 in . Ib s. 90 in . Ib s. 150 in . Ib s . (P 10)* - B ra c k e t to A x le 150 in . lb s . 150 in . Ib s. - 150 in . Ib s . 150 in, lbs. 150 in. 150 in . Ibs. 150 in . Ibs. A tta c h in g N uts R e ta in in g C lip s - S c re w s - B o lts 150 in . lb s . - - - lb s . 100 in . 150 in . Ibs. Ib s. 18 ft. Ibs. T o rq u e to sea l or 100 in . lb s . m a x . R e p la ce v a lv e if it w ill not seal at 100 in . lb s . B rake B le e d e r V a lv e s H y d ro -B o o s t - P edal Rod - lb s . - R ear B rake A n c h o r Pin Front B rake H ose 50 in . 25 ft. P 30(32) M o d e ls - 15 in . Ib s. - _ 25 ft. Ib s . - _ - 45 ft. Ib s . - - - 25 f t. Ib s . P edal R od B oot - P 3 0 (3 2 )M o d e ls - P ivot L e ver Rod R e ta in e r - - P iv o t L e ver B olt - B o o ste r B ra cke ts - B o o s te r B race at D ash or R a d . S u p t. - P ow er S teering P um p to B o o ste r Lin e 25 ft. IbS. 25 ft. - B o o s te r to G ea r Line 25 ft. lb s . _ 25 ft. - R e tu rn L in e a t B o o s te r & G e a r 25 ft. lb s . - - R etu rn L in e C la m p S crew 15 in . lb s . _ - L in e C la m p to B ra c k e t S c re w 150 in . lb s . - H o se C la m p to S k ir t S c re w 40 in . lb s . - L in e C la m p to F ra m e B o lt _ - Ib s . - - 150 in . Ib s . Ib s. 25 ft. Ib s . Ibs. 25 ft. Ib s. 25 ft. Ibs. 25 ft. Ib s. 15 in . Ibs. 15 in . Ib s. - 150 ft. Ibs. 150 in . Ib s. - - - - - 18 ft. Ib s. *20 ft. lb s . (P 20 -30) TR U C K SUPP — SPECS SPECIFICATIONS 9 ENGINE SECTION 6 GENERAL DATA: Type I n L in e 250 D isplacem ent (cu. in.) V8 292 Bore 350 3 7/8 454 4 Stroke 3.53 4.12 3.48 4 1/4 4 Com pression Ratio 8.25:1 8 .0 :1 8.5:1 8.25:1 Firing Order 1-5-3-6-2-4 1-8-4-3-6-5- 7-2 CYLINDER BORE: 3.8745 - 3.8775 Diam eter Out o f Round Taper 3.9995 - 4.0025 .0005 Max. Production 4.2495 - 4.2525 .001 Max .002 Max. Service .0005 Max. T hrust Side P roduc­ tion Relief Side .0005 Max. .001 Max. Service .005 Max. PISTON: .0005-.0015 .0025 Max. Production Clearance Service .0018-.0028 .0026-.0036 .0045 Max. .0007-.0013 .0027 Max. .0035 Max. .0020-.0040 .0012 - .0032 .0017 - .0032 PISTON RING: C 0 M P R E S S I 0 Clear­ ance Groove ] P roduc­ tion .0012 - .0027 2 nd .0012-.0032 Hi Limit Production + .001 Service Produc­ tion Gap N 0 Top Top 2 nd .010 .010 - .020 Production I L Gap .005 Max. .005-.0055 .002 - .007 Service Hi Limit Production + .001 P roduction .015 - .055 Hi Limit Production + .01 Service .010 - .020 Hi Limit Production + .01 Service Groove Clearance .020 .013 - .025 .0005 - .0065 .010 - .630 PISTON PIN: Diam eter P roduction .9270 - .9273 .00015 - .00025 Service .001 Max. Clearance Fit in Rod .9895 - .9898 .00025 - .00035 .0008 - .0016 Interference TR U CK S U P P — SPECS SPECIFICATIONS 10 CRANKSHAFT: #1 All 2.2983 - 2.2993 Diam eter Main Journal Main Bearing Clearance .001 (Max.) .0002 (Max.) Production .001 (Max.) Service All .0003 All .0008 .0029 .0034 #1 .0008 - .0020 .006 - .010 .002 - .006 Diam eter 1.999 - 1.2000 .0003 (Max.) P roduction .001 (Max.) P roduction .0002 (Max.) .001 (Max.) Service .0007 - .0027 P roduction Rod Bearing Clearance 2.1985 - 2.1995 2.199 - 2.200 2.099 - 2.100 Service O ut of R ound #5 .0024 - .0040 #5 .0017 - .0033 #1 - .002 (Max.) All O thers .0035 (Max.) Service Taper #1-2-3-4 .0013 - .0025 #2-3-4 .0011 - .0023 Production C rankshaft End Play Crankpin #5 2.7478 - 2.7488 .0002 (Max.) Service O ut of R ound #2-3-4 2.7481 - 2.7490 #5 2.4479 - 2 4488 Production Taper 2.7485 - 2.7494 #1-2-3- 4 2.4484 - 2. 4493 .0009 - .0025 .0013 - .0035 .0035 (Max.) Service .008 - .014 .0006 - .0017 Rod Side Clearance .013 - .023 CAMSHAFT: Lobe Lift ± .002" Intake .2217 .2315 .2600 .2343 E xhaust .2217 .2315 .2733 .2343 1.8682 - 1.8692 Journal D iam eter 1.9482 -1.9492 Camshaft R u n o u t .0015 Max. Camshaft End Play .001 - .005 (In-Line Engine) VALVE SYSTEM: Hydraulic L ifter 1.75:1 Rocker Arm Ratio Valve Lash 1.50:1 Intake One T urn D ow n From Zero Lash E xhaust Face Angle (Int. & Exch.) 45° Seat Angle (Int. & Exh.) 46° .002 (Max.) Seat R u n o u t (Int. & Exh.) Seat Width 1/32 - 1/16 Intake E xhaust Stem Clearance P roduc­ tion 1/16 - 3/32 .0010 - .0027 Int. Exh. | E xhaust 1.91 Inlet 2.03 2.12 Closed 55-64 @ 1.66 85-93 @ 1.69 76-84 @ 1.61 76-84 @ 1.70 74-86 @ 1.88 Open 180-192 @ 1.27 174-184 @ 1.30 183-195 @ 1.20 194-206 @ 1.25 288-312 @ 1.38 1-21/32 1-5/8 1-5/8 1-23/32 1-7/8 Installed Height ± 1 /3 2 " Damper .0012 - .0029 Hi Lim it P roduction + .001 Intake - + .002 E xhaust Free Length Pressur e lbs. @ i n. .0010 - .0027 .0015 - .0032 Service Valve Spring (Outer) 1.70:1 190 Free Length - 1.94 1.86 A pprox. # o f Coils - 4 4 TR U C K SUPP — SPECS SPECIFICATIONS 11 TUNE-UP CHART ENGINIS Type Displacement Make & Number Gap 292 250 350 AC-R44T AC—R46TS .035 454 150 psi 130 psi COMPRESSION © SPARK PLUG V8 In Line AC—R45TS .035 .045 DISTRIBUTOR Timing © DRIVE BELT © SEE IGNITION SPECIFICATIONS Fan P /S and Air Pump 50 lb. Min 7 5 ± 5 lbs. (U sed)125±5 lbs.(N ew )U sing Strand Tension Gauge A /C Compressor 65 lbs. Min 9 5 ± 5 lbs. (U sed)140±5lbs. (New)Using Strand Tension Gauge Refer to Section 0 of this Manual AIR CLEANER © Hydraulic - 1 turn down from zero lash VALVE LASH Refer to Exhaust Emission Tune-Up Label IDLE RPM FUEL PUMP © Pressure in lbs. 3 -1 /2 to 4 -1 /2 Volume CRANKCASE VENTILATION 7 to 8 -1 /2 1 pint in 30-45 seconds (a) cranking speed Refer to Section 0 of this Manual © PSI At Cranking Speed, throttle wide open - Maximum variation, 20 PSI between cylinders. © At idle speed with vacuum advance line disconnected and plugged. On Step Van vehicles, use number tw o cylinder and timing tab on bottom of cover. © D o not pry against A.I.R. pump housing. © C A UTIO N :In addition to its function of filtering air drawn into the engine through the carburetor, the air cleaner also acts as a flame arrestor in the event the engine backfires. Because backfiring may cause fire in the engine compartment, the air cleaner should be installed at all times unless|its removal is necessary for repair or maintenance services. (5) Replace filter element located in carburetor inlet as indicated in Section 0 of this Manual. TR U CK SUPP — SPECS SPECIFICATIONS 12 ENGINE TORQUES Usage Size 1 /4 -2 0 Camshaft Thrust Plate C rankcase Front Cover Flyw heel Housing Cover Oil F ille r Bypass Valve Oil Pan (To Crankcase) Oil Pan (To Front Cover) Oil Pump Cover Rocker Arm Cover In Line 250 292 5 /1 6 -1 8 Camshaft Sprocket Clutch P re ssu re Plate Oil Pan (To Crankcase) Oil Pump Push Rod Cover Water Pump 20 lb. ft. 75 lb. 115 lb. 50 lb. 15 lb. Connecting Rod Cap 7 /1 6 -1 4 Cylinder Head Main Bearing Cap Oil Pump Rocker Arm Stud 7 /1 6 -2 0 Flyw heel Torsional Damper 1 /2 -1 3 Cylinder Head Main Bearing Cap 1 /2 -1 4 Tem perature Sending Unit 1 /2 -2 0 T orsicnal Damper Oil F ilter Oil Pan Drain Plug F lyw heel 14mm 5/8 Spark Plug 454 80 lb. in. 80 lb. in. 50 lb. in. 70 lb. in. 45 lb. in. 35 lb. ft. 3 /8 -2 4 262& 350 80 lb. in. 80 lb. in. Connecting Rod Cap Clutch P re ssu re Plate D istributor Clamp Flyw heel Housing Manifold (Exhaust) Manifold (Exhaust to Inlet) Manifold (inlet) M anifold-to-head Therm ostat Housing Water Outlet Water Pump Mark IV V-8 80 lb. in. 1 1/32-24 3 /8 -1 6 Sm all V -8 55 lb. in. 80 lb. in. 50 lb. in. 20 lb. ft. in. in. in. in. 65 lb. in. 1 135 lb. in. 35 lb. ft. 20 lb. ft. 30 lb. ft. 20 lb. ft.® / tn 30 lb . f t . ^ ' 30 lb. ft. 30 lb. ft. | 35 lb. ft. 30 lb. ft. 30 lb. ft. 30 lb. ft. 40 lb. ft. 65 lb. ft. 45 lb. ft. 50 lb. ft. 65 lb. ft. 70 lb. ft. 80 lb. ft. 65 lb. ft. 50 lb. ft. 60 lb. ft. 60 lb. ft. 60 lb. ft. 65 lb. ft. 95 lb. ft. 110 lb. ft. 20 lb. ft. Hand Tight 85 lb. ft. 25 lb. ft. 1 20 lb. ft. 110 lb. ft. 15 lb. ft. Inside bolts on 350 engine 30 lb. ft. Outer bolts (Integral Head) 20 lb. ft. 8 TR U C K SUPP — SPECS SPECIFICATIONS 13 CARBURETOR SECTION 6M IDENTIFICATION P K C 10 2 0- 30 20 20- 30 2 0- 3 0 and Type Type LD4 1 MV M anual A u to m a tic M anual A u to m a tic 17056003 17056002 17056 303 17056302 — 250L6 HD LD4 1 MV 17056007 1 7056006* _ 292L6 HD L25 1 MV 17056009 17 056 008 1 7056309 17056308 — 350V8 LD LF5 2GC 17056115 17 056116 350V8 LD LF5 2GC 17056123 17056124 — — 350V8 LD LS9 M4MC 17056209 17 056 208 17056 509 17056508 10 350V8 LD LS9 M4MC 17056219 17056218 1 7056519 17056518 20 - 30 350V8 HD LS9 4MV 7045214 7 04 52 14 7 04 55 8 4 70455 84 350V8 HD LS9 4MV 7045216 7 04 52 16 7 045 5 86 70455 86 350V8 HD LS9 4MV 7045213 70452 13 7 045 5 83 70455 83 704 55 85 10 20- 30 10-20 350V8 HD LS9 4MV — 7 04 52 15 _ 400V8 HD LF4 4MV _ 7 04 52 25 — 70455 89 400V8 HD LF4 4MV — 70452 29 — 70455 88 454V8 LD LF8 M4ME — 17056221 — — 454V8 HD LF8 4MV _ 17 056212 — — 454V8 HD LF8 4MV 17056212 17056212 — — 30 454V8 HD LF8 4MV _ 17 056217 — — 30MH 454V8 HD LF8 M4MC _ — — 17056512 454V8 HD LF8 M4MC _ _ 17056512 17056512 454V8 HD LF8 M4MC - - 30MH 20 - 30 10-20 10 30MH 20- 30 10-20 and C alifornia _ 10 10-20 rel LD Federal B ar­ m ent 250L6 10 10- 20- 30 RPO D isplace­ G 10 10 10 CARBL RETOR ENGINE VEHICLE 2 0- 30 30 17056517 *17056004 on CID w ith air conditioning. CARBURETOR ADJUSTMENTS 2GC Carburetor Choke Rod NUMBER Float Vacuum Float Pump Rod (A) A utom atic Trans. Level (Fast Idle Choke Unloader Break Drop Setting Cam) (M) Manual Trans. 170561 1 5(M) 21/32 1-9/32 1 70561 16(A) 21/32 1-9/32 1 7 0 5 6 1 23(M) 17056124(A) 21/32 1-9/32 21/32 1-9/32 1-11/16 1-11/16 .260 .130 .325 INDEX .260 .130 .325 1 NR 1-11/16 1-11/16 .260 .130 .325 INDEX .260 .130 .325 1 NR TR U CK SU PP — SPECS | SPECIFICATIONS 14 CARBURETOR ADJUSTMENTS 1 MV NUMBER Float Primary A uxiliary (Fast Idle Vacuum Vacuum Cam) Break Break M etering (A) A utom atic Trans. Level Carburetor Choke Rod Choke Unloader Rod (M) Manual Trans. Setting 17056002(A) 1 1/ 3 2 .080 .130 .165 .265 .335 17056003(M) 1 1/ 3 2 .080 .145 .180 W.O. .335 1 7056004(A) 1 1/ 32 .080 .130 .165 .335 Refer to 17056006(A) 1/4 .080 .130 .165 .265 — .270 Section .165 — .275 6M for 17056007(M) 1/ 4 .070 .130 1 7056008(A) 1/ 4 .070 .150 .190 — .275 Service 17056009(M) 1/ 4 .070 .150 .190 — .275 Procedure 1 7056302(A) 1 1/32 .080 .155 .190 W.O. .325 17056303(M) 1 1/32 .080 .180 .225 W.O. .325 .275 .275 1 7056308(A) 1/ 4 .070 .150 .190 _ 17056309(M) 1/4 .070 .150 .190 — 4 M V Carburetor NUMBER (A ) A u to m a tic Trans. (M ) Float Pum p Level R od* M a n u a l Trans. C hoke Rod A ir Vacuum A ir Un­ C hoke (Fast V a lve B reak V a lv e load er S e t­ Idle D ashp ot S p rin g Cam ) 7045213(A/M) tin g W in d u p 1 1/32 1 1/32 9/32 9/32 .290 .290 .015 .015 .145 .145 7/8 7/8 .295 9/32 .290 .015 .145 7/8 .295 7045216(A/M) 1 1/ 3 2 1 1/32 9/32 .290 .015 .145 7/8 .295 7045225(A) 1 1/32 9/32 .015 .138 3/4 .295 to .015 .138 3/4 .295 Section .015 .155 7/8 .295 6M 7/8 .295 for 7/8 .295 Choke 7/8 3/4 .295 Rod Adjust. 3/4 7/16 7/16 .295 .295 .295 7045214(A/M) 7045215(A) 7045229(A) 7045583(A/M) 1 1/ 3 2 9/32 1 1/32 9/32 .290 .290 .290 7045584(A/M) 1 1/32 9/32 .290 .015 7045585(A) 7045586(A/M) 1 1/32 9/32 .290 .015 .155 .155 1 1/32 9/32 .290 .015 .155 7045588(A) 1 1/32 9/32 1 1/ 3 2 3/8 3/8 9/32 9/32 9/32 .290 .290 .290 .290 .015 7045589(A) .155 .155 .155 .1 55 1 7 0 5 6 2 12(A/M) 1 705621 7(A) .015 .015 .015 .295 .295 Refer TR U C K SU PP — SPECS SPECIFICATIONS 15 CARBURETOR ADJUSTMENTS - Continued M4MC Car buretor NUMBER (A ) A u to m a tic Trans. Float Pum p Level Rod* C hoke C hoke Rod A ir F ro n t R ear A ir U n­ C hoke lo a d e r S e t­ Coil (Fast V a lve V acuum V acuum V a lv e Lever Idle D ashp ot B reak B reak S p rin g _ Cam ) tin g W in d u p 1 7056208(A) ★★ 9/32 .120 .325 .015 .185 1 7056209(M) ★★ 9/32 .1 20 .325 .015 .185 — 17056218(A) 5/16 9/32 .120 .325 .015 .185 ___ 7/8 .325 2NL 1 7 0 5 6 2 1 9(M) 5/16 9/32 .120 .325 .015 .185 — 7/8 .325 3NL 1 7056508(A) ★★ 9/32 .120 .325 .015 .185 — 7/8 .325 2NL 1 7056509( M) ** 9/32 .1 20 .015 .185 — 7/8 .325 1NL 1 705651 2(A/M) 17056517(A) 7/16 9/32 .1 20 .325 .325 .015 .185 — 7/8 .275 INDEX 7/16 9/32 .120 .325 .015 .185 — 7/8 .275 INDEX 17056518(A) 5/16 9/32 .1 20 .325 .015 ___ 7/8 .325 1 7 0 5 6 5 1 9(M) 5/16 9/32 .1 20 .325 .015 .185 .185 — 7/8 .325 2NL 1NL 7/8 .325 2NR 7/8 .325 2NL 7/8 .325 3NL * *N e e d le Seat w ith G ro ove a t up per edge 5 /1 6 . N eedle Seat w ith o u t G ro ove a t u p p e r edge 7 /1 6 . M4M E Carburetor 1 7056221(A) * 7/16 9/32 120 .300 .015 1 60 In n e r Pum p Rod Lo cation IDLE SPECIFICATIONS SHOWN IN RPM LIGHT DUTY EMISSION REQUIREMENTS ENGINE DISPLACE­ MENT C.I.D. BBL. TRANS. USAGE LOW (BASE) IDLE CURB IDLE FAST IDLE IDLE MIXTURE EMIS­ SION FAMILY 250 1 FED FED 575/550DR 12F1U 425N 550DR 900N 2100N + 250 AUTO MAN 425DR 1 2100N + 12F1U 250 1 CAL 425DR 600DR 2100N + 250 1 AUTO MAN 1075/900N 630/600DR CAL 425N 1000N 2100N + 1150/1000N 350 2 AUTO 350 2 350 4 350 4 350 4 350 454 12F1U 600DR — 650/600DR 12FIU 12J2 800N — 900/800N 12J2 FED — MAN FED — AUTO MAN FED — 600DR 1600N 650/600DR 12J4B FED — 800N 1600N 900/800N 12J4B 600DR 1600N 650/600DR 12J4 800N 600DR 1600N 900/800N 12J4 1600N 650/600DR 12R4D CAL — 4 AUTO MAN CAL — 4 AUTO FED — TR U CK SU PP — SPECS SPECIFICATIONS 16 HEAVY DUTY EMISSION REQUIREMENTS 250 292 1 A/M FED 45 0 600N 2400N 700/600 GM111 1 A/M F/C 600N 2400N 700/600 GM112A 350 4 A/M FED 450 — 600N 1600N 750/600 GM1 13 CAL — 700N** 1600N 800/700 GM 1 13 F/C — 700N** 1600N 770/700 GM1 13 700N 1700N 800/700 GM1 15 700N* 1700N 750/700 GM1 15 4 350 + * A/M 400 4 454 4 A/M FED — 454 4 A/M CAL — AUTO W ith v a c u u m a d v a n c e hose c o n n e c te d and EGR hose d is c o n n e c te d a n d p lu g g e d . 1400 rpm fo r th ro ttle return c o n tro l system w ith va c u u m a p p lie d to d ia p h ra g m an d d is trib u to r v a c u u m and EGR c o n n e c te d . ** 1500 rpm for th ro ttle return c o n tro l system w ith v a c u u m a p p lie d to d ia p h ra g m an d d is trib u to r v a c u u m and EGR c o n n e c te d . TORQUE SPECIFICATIONS 1MV Carburetor Screw A ir Horn to Bowl Air Cleaner Bridge Throttle Body to Bowl Needle Seat Metering Jet Fuel Inlet Nut Fast Idle Cam Choke Lever Pump Lever * L o c tite A W 2GC Carburetor Torque (in. Ibs.) 45 70 180 45 40 400 50 25 30* o r e q u iv a le n t M4MC/M4ME Carburetor Torque Screw (in. Ibs.) THROTTLE BODY Throttle Body to Bowl 46 CHOKE HOUSING Choke Lever Choke Housing Attaching Choke Housing Cover 14 46 26 AIR HORN A ir Horn to Bowl 10-32 A ir Horn to Bowl 8-32 A ir Horn to Throttle Body Choke Lever Vacuum Break Unit Fuel Inlet Nut Needle Seat Metering Jet Solenoid Bracket Torque THROTTLE BODY Throttle Body to Bowl 72 BOWL Cluster Fast Idle Cam Metering Jet 46 58 40 CHOKE HOUSING Choke Lever Choke Hsg. to Throttle Body Choke Housing Cover 14 46 26 AIR HORN A ir Horn to Bowl Vacuum Break Unit Choke Shaft Fuel Inlet Nut Needle Seat 46 26 14 400 45 4MV Carburetor Torque Screw 46 26 46 14 26 400 45 40 71 (in. Ibs.) Screw A ir Horn to Bowl 10-32 A ir Horn to Bowl 8-32 A ir Horn to Throttle Body Throttle Body to Bowl Vacuum Break Unit Solenoid Bracket Fuel Inlet Nut Metering Jet Needle Seat (in. Ibs.) 46 26 46 46 26 71 400 40 45 TRUCK SU PP — SPECS SPECIFICATIONS 17 ENGINE ELECTRICAL SECTION 6Y STARTING MOTOR Application Model No. 250 L-6 (LD4) 1108778 Spec. No. Battery Size Volts 3573 2300 Watts 9 50-80* 5500-10500 3573 2300 Watts 9 50-80* 5500-10500 Free Speed Amperes RPM (C & K-10) 250 L-6 (LD4) 1108779 (G-Van) 1108780 292 L-6 (L25) 2438 2900 Watts 9 5 0- 8 0 * 3500-6000 1108781 350 & 40 0 V8 3563 2900 Watts 9 6 5- 9 0 * 7500-10500 3563 4000 Watts 9 6 5- 9 0 * 7 5 0 0 - 1 0 50 0 3563 40 00 Watts 9 65-90* 7500-10500 (LF4,LF5,LS9) 454 V8 (LF8) 1108781 (Exc P30032) 454 V8 (LF8) 1108782 (P30032) i ncl udes Solenoid GENERATORS Application M odel No. Delco Rem y Field C urrent A m p s (8 0 °F ) Spec. No. @ 1102491 A ll 2 5 0 L -6 (Base). G -T ruck 2 9 2 Cold O u tp u t* Amps @ 5000 Rated Hot RPM O u tp u t* * Am ps 1 2 Volts 4519 4 .0 - 4 .5 33 37 L - 6 (Base). 1102478 A ll L -6 - w ith C 4 2 4520 4 .0 - 4 .5 51 55 1102479 A ll V -8 - w ith C 4 2 4520 4 .0 - 4 .5 51 55 - w ith 4522 4 .0 - 4 .5 57 61 4521 4 .0 - 4 .5 38 42 1102480 A ll V -8 K 7 6 . P 3 1 8 3 2 Truck 4 5 4 V -8 (Base). G 3 0 0 0 3 T ruck 3 5 0 V -8 1102489 (Base) A ll L -6 - w ith P -T ruck 2 9 2 K 79. L -6 (Base) 1102490 A ll L -6 - w ith K 7 6 4522 4 .0 - 4 .5 57 61 1102394 A ll C -K -G T ru ck 4519 4 .0 - 4 .5 33 37 4521 4 .0 - 4 .5 38 42 (Exc G 3 0 0 0 3 ) V -8 1102841 (Base) A ll P -Truck (Exc P 3 1 8 3 2 ) V -8 A ll V -8 - w ith (Base) K79. * G en era tor te m p e ra tu re a p p ro x im a te ly 80°F. * * A m b ie n t T e m p e ra tu re 80°F. TR U CK SU PP — SPECS SPECIFICATIONS 18 DISTRIBUTOR APPLICATION MODEL NO. EMISS CLASS L.D. 1112863 L -6 250 C -1 0 (L D 4 ) H.D. Federal (0 3 ) 4 -S p d T rans C -1 0 (0 3 ) & CENTRIFUGAL VACUUM INITIAL SPARK PLUG ADVANCE ADVANCE TIMING (TYPE & GAP) 10° BTC R 46TS 0° @ 1100 0° @ 7° @ 2300 18 ° @ 16° @ 4200 4' Hg 1 2" Hg (.0 3 5 ) C -1 0 A u to Trans 1110667 L -6 250 (L D 4 ) C alif C & G -1 0 M anual Trans 1110650 L -6 250 C alif A u to Trans L -6 250 (L D 4 ) Federal 3 -S p d Trans L -6 250 C & (L D 4 ) Federal A ll Trans L -6 4* 12' Hg 6° BTC Hg R 46T S (.0 3 5 ) (a) 4 2 0 0 0° @ 1 100 0° @ 7° @ 2300 15 ° @ 4* 12* Hg 10 ° BTC Hg R 46T S (.0 3 5 ) (a) 4 2 0 0 0° @ 1000 0° @ 7° @ 1600 24° @ 4* 15" Hg 6° BTC Hg R 46T S (.0 3 5 ) (a) 4 2 0 0 0° @ 1 100 0° @ 14° @ 2300 10° @ 10' Hg 6° BTC 1 3 ' Hg R 46T (.0 3 5 ) 24° @ 4 1 0 0 292 & 15 ° @ 20° K -1 0 C.K.G 0° @ 1600 16° C & G -1 0 1112887 1000 7° @ 20° (L D 4 ) C & G -1 0 1110666 0° @ (L 2 5 ) P -2 0 . 8° BTC 30 R 44T (.0 3 5 ) A ll Trans 1110664 L -6 C & 292 (L 2 5 ) C alif P -1 0 -2 0 -3 0 G -2 0 -3 0 : K -2 0 M anual Trans 0° @ 1 100 0° @ 6° @ 2000 10 ° @ 14° @ 2300 10' 13' Hg 8° BTC Hg R44T (.0 3 5 ) 24° @ 4 1 0 0 C -1 0 - 2 0 - 3 0 G -2 0 -3 0 P -1 0 -2 0 K -2 0 A u to Trans 1112880 1112905 V-8 350 2 B B L (LF5) 0° @ 1200 Federal A u to T rans 12° @ 2000 M an T rans 22° V -8 350 4BBL C alif (LS9) V -8 (LS9) 350 4BBL Federal 18° @ 1 2 ” H g 0° @ 1200 0° @ 12° @ 2000 15° @ 22° 1112888 (a) 4 2 00 6° BTC 0° @ 4 ” Hg 12' Hg (.045) 2° BTC 6° BTC Hg R 45T S (.0 4 5 ) (a) 4 2 0 0 0° @ 1 100 0° @ 12° @ 1600 18° @ 16° 6' R 45TS 4' Hg 1 2 ' Hg 8° BTC R 45T S (.0 4 5 ) (a) 2 4 0 0 TR U CK S U PP — SPECS SPECIFICATIONS 19 DISTRIBUTOR — Continued E M IS S C LA S S A P P LIC A T IO N M O D E L NO. L.D . 1112884 V -8 350 4BBL 400 4BBL 350 4BBL H.D . Calif (LS9) V -8 C E N T R IFU G A L VACUUM IN IT IA L SPARK ADVANCE ADVANCE TIM IN G (TYPE & 1 150 0° @ 17° @ 2900 10 ° @ 22° @ 4200 0° @ 8" Hg 13" PLUG G AP) R 44T X 2° BTC Hg (.0 6 0 ) (LF4) 1 1 12940 V -8 Federal (LS9) 0° @ 1200 15° @ 2 700 0° @ 15 ° @ 8" Hg 1 5 .5 " 8° BTC R44TX Hg (.0 6 0 ) 20° @ 4 2 0 0 1 1 12941 V -8 400 Federal 4BBL (LF4) 0° @ 1000 0° @ 8° @ 1600 10 ° @ 8" Hg 13" 4° BTC R 44T X Hg (.0 6 0 ) 19° (a) 3 4 5 0 1 1 12886 V -8 454 w/ 1112494 454 Federal 4BBL P /U w /o Cat C o n v e rte r V -8 454 0° @ 1300 0° @ 12° @ 4200 18 ° @ 4" Hg 7" Hg 10" Hg 12° BTC R 45T S (.0 4 5 ) C -1 0 & 454 17" 8° BTC R 45T S Hg (.0 4 5 ) 20° @ 4 2 0 0 R44T (.0 4 5 ) P /U P -3 0 1 100 0° @ 14° @ 2800 20° @ 20° @ 4200 0° @ Calif 4BBL P /U Cat C o n v e rte r w /R P O C -1 0 0° @ 15 ° @ S ubu rban (LF8) C -1 0 w /o 1 100 2800 F44 C 2 0 -3 0 V -8 0° @ 14° @ Federal 4BBL (LF8) C -1 0 w /R P O * P /U Cat C o n v e rte r V -8 (LF8) C -1 0 1112869 Federal 4BBL (LF8) C -1 0 Or 6" Hg 15" R 44T 8° BTC Hg (.0 4 5 ) F44 S ub u rb a n C 2 0 - 3 0 & P -3 0 - N one (E le c tro n ic a lly G ove rne d) BATTERY M odel No. A p p lic a tio n Cold Crank Rate C ranking Power @ 25 A m p. Reserve 0° F. (W atts) C apacity (M inutes) Y87P 250 L-6 275A @ 0° F 2500 60 R87P 292 L-6 305 & 350A @ 0° F 3200 80 465 A @ 0° F 400 0 125 350 V-8 R89WP 454 V-8 & RPO Option R89-5 RPO UA1 465 A @ 0° F 400 0 125 R87-5 RPO TP2 430 A @ 0° F 3500 100 TRUCK SU PP — SPECS SPECIFICATIONS 20 CLUTCH AND MANUAL TRANSMISSION SECTION 7M THREE SPEED SAG INAW Clutch Gear Retainer to Case B o lts ................ Side Cover to Case Bolts ................................... Extension to Case Bolts..................................... Shift Lever to Shifter Shaft B o l t s ................... Lubrication Filler P l u g ..................................... Transmission Case to Clutch Housing Bolts . . Crossmember to Frame N u t s ........................... Crossmember to Mount B o l t s ........................ 2-3 Cross Over Shaft Bracket Retaining Nut . 1-Rev. Swivel Attaching B o l t ........................... Mount to Transmission B o l t ........................... THREE SPEED TREMEC 15 ft. 15 ft. 45 ft. 25 ft. 13 ft. 75 ft. 25 ft. 40 ft. 18 ft. 20 ft. 50 ft. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. Clutch Gear Retainer to Case B o lts ................ .... 35 Top Cover to Case Bolts .................................. .... 30 Extension to Case B o lts......................................... 45 Shift Lever to Shifter Shaft Bolts .................. .... 25 Lubrication Filler Plug ......................................... 15 Transmission Case to Clutch Housing Bolts . . 75 Crossmember to Frame N u ts ................................ 25 Crossmember to Mount Bolts ......................... .... 40 2-3 Cross Over Shaft Bracket Retaining Nut . 18 1- Rev. Swivel Attaching B o l t ......................... .... 20 Mount to Transmission Bolt ................................ 50 ft. lbs. ft. lbs. ft. lbs. ft. lbs. ft. lbs. ft. lbs. ft. lbs. ft. lbs. ft. lbs. ft. lbs. ft. lbs. THREE SPEED MUNCIE NEW PROCESS TRANSFER CASE MODEL 205 Clutch Gear Retainer to Case B o lts ................ ...15 ft. lbs. Side Cover to Case Bolts ................................ ...15 ft. lbs. Extension to Case B o lts ......................................45 ft, lbs. Shaft Lever to Shifter Shaft B o l t s ................ ...25 ft. lbs. Lubrication Filler Plugs..................................... ...13 ft. lbs. Transmission Case to Clutch Housing Bolts . . 75 ft. lbs. Crossmember to Frame N u t s ........................... ...25 ft. lbs. Crossmember to Mount Bolts..............................40 ft. lbs. Transmission Drain P lu g ......................................30 ft. lbs. 2-3 Cross Over Shaft Bracket Retaining Nut. 18 ft. lbs. 1-Rev. Swivel Attaching B o l t ..............................20 ft. lbs. Mount to Transmission Bolt ..............................50 ft. lbs. FOUR SPEED MUNCIE (C H 4 6 5 ) Rear Bearing R e ta in e r ..................................... '23 ft. lbs. Cover Bolts........................................................... 231ft. lbs. Filler P l u g . . . ................................................... 33 | ft. lbs. Drain P l u g ........................................................... 33 Ift. lbs. Clutch Gear Bearing Retainer Bolts................ 14 ft. lbs. 95 ft. lbs. Universal Joint Front Flange N u t ................... Power Take Off Cover B o lts ........................... 17 ft. lbs. Parking B ra k e ..................................................... 22 ft. lbs. Countergear Front Cover Screws..................... 25 in. lbs. Rr. Mainshaft Lock Nut (4 Whl. Drive Mdls.) 100 ft. lbs. Transmission To Clutch Housing B o lts........... 75 ft. lbs. Crossmember to M o u n t..................................... 40 ft. lbs. Mount to Transm ission..................................... 50 ft. lbs. Idler Shaft Lock N u t ........................................ 200 ft. lbs. Idler Shaft Cover B o lts ..................................... 18 ft. lbs. Front O utput Shaft Front Bearing Retainer B o lts................................................ 30 ft. lbs. Front Output Shaft Yoke Lock Nut ........... 200 ft. lbs. Rear Output Shaft Bearing Retainer Bolts. . . 30 ft. lbs. Rear Output Shaft Housing B o l t s ................... 30 ft. lbs. Rear Output Shaft Yoke Lock N u t ................ 150 ft. lbs. P.T.O. Cover Bolts ........................................... 15 ft. lbs. Front Output Shaft Rear Bearing Retainer B o lts ................................................ 30 ft. lbs. Drain and Filler P lu gs........................................ 30 ft. lbs. Transfer Case to Frame B o lts ........................... 130 ft. lbs. Transfer Case to Adapter B o lts ...................... 25 ft. lbs. Adapter Mount B o lts ........................................ 25 ft. lbs. Transfer Case Bracket to Frame Nuts (Upper) 30 ft. lbs. Transfer Case Bracket to Frame Nuts (Lower) 65 ft. lbs. Adapter to Transmission Bolts -(Manual T ransm ission)................................................ 22 ft. lbs. Adapter to Transmission Bolts - (Automatic Transm ission)................................................ 35 ft. lbs. Transfer Case Control Mounting Bolt ...........100 ft. lbs. TR U C K SU PP — SPECS SPECIFICATIONS 21 A U T O M A T IC T R A N S M IS S IO N S SECTION 7A NEW PROCESS TRANSFER CASE MODEL 203 Adapter to Transfer Case Attaching Bolts . . . Adapter to Transmission Attaching Bolts. . . Transfer Case Bracket to Frame nuts (upper) Transfer Case Bracket to Frame nuts (lower) Transfer Case Shift Lever Attaching Nuts. . . Transfer Case Shift Lever Rod Swivel Lock N u t s ..................................................... Transfer Case Shift Lever Locking Arm Nut . Skid Plate Attaching Bolt Retaining Nuts . . . Crossmember Support Attaching Bolt Retaining N u t ................................................ Adapter Mount B o lts ........................................ Intermediate Case to Range Box Bolts . . . . Front Output Bearing Retainer B o lts ........... O utput Shaft Yoke N u t s ..................... Front O utput Rear Bearing Retainer Bolts. . . Differential Asrembly Screws. . . . .............. Rear O utput Shaft H ousing.............................. Poppet Ball Retainer N u t ................................ Power Take Off Cover Bolts ........................... Front Input Bearing Retainer B o lts................ Filler P l u g ........................................................... 38 40 50 65 25 ft. ft. ft. ft. ft. lbs. lbs. lbs. lbs. lbs. 50 ft. lbs. 150 in. lbs. 45 ft. lbs. 45 ft. 25 ft. 30 ft. 30 ft. 150 ft. 30 ft. 45 ft. 30 ft. 15 ft. 15 ft. 20 ft. 25 ft. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. lbs. TURBO HYDRA-MATIC 350 Pump Cover to Pump B o d y .............................. 17 ft. lbs. Pump Assembly to Case................................ 18 -1/2 ft. lbs. Valve Body and Support P l a t e ........................ 130 in. lbs. Parking Lock B ra c k e t........................................ 29 ft. lbs. Oil Suction Screen ........................................... 40 in. lbs. Oil Pan to C a s e ................................................... 130 in. lbs. Extension to Case................................................ 25 ft. lbs. Modulator Retainer to C a se .............................. 130 in. lbs. Inner Selector Lever to S h a f t........................... 25 ft. lbs. Detent Valve Actuating B racket...................... . 52 in. lbs. Converter to Flywheel B o l t s ........................... 35 ft. lbs. Under Pan to Transmission C a se ..................... 110 in. lbs. Transmission Case to Engine ........................... 35 ft. lbs. Oil Cooler Pipe Connectors to Transmission Case (straight pipe fittin g ) ........................... 25 ft. lbs. (tapered pipe fittin g )............................ 15 ft. lbs. Oil Cooler Pipe to Connectors ..................... 10 ft. lbs. Detent Cable to Transmission........................... 75 in. lbs. 112 in. lbs. Detent Cable to C arb........................ TURBO HYDRA-MATIC 4 0 0 /4 7 5 Pump Cover B o l t s .............................................. 18 ft. lbs. Parking Pawl Bracket B o l t s .............................. 18 ft. lbs. Center Support B o lt........................................... 23 ft. lbs. Pump to Case Attaching B o l t s ........................ 18 ft. lbs. Extension Housing to Case Attaching B olts. . . 23 ft. lbs. Rear Servo Cover B o lts ...................................... 18 ft. lbs. 7 ft. lbs. Detent Solenoid Bolts ...................................... 8 ft. lbs. Control Valve Body B o lts................................ Bottom Pan Attaching S c r e w s ........................ 12 ft. lbs. Modulator Retainer B o lt................................... 18 ft. lbs. Governor Cover B o lts........................................ 18 ft. lbs. 8 ft. lbs. Manual Lever to Manual Shaft N u t ................ Manual Shaft to Inside Detent L e v e r ........... 18 ft. lbs. Linkage Swivel Clamp N u t .............................. 43 ft. lbs. Converter Dust Shield Screws........................... 93 ft. lbs. Transmission to Engine Mounting Bolts . . . . 35 ft. lbs. Converter to Flywheel B o l t s ........................... 35 ft. lbs. Rear Mount to Transmission B o l t s ................ 40 ft. lbs. Rear Mount to Crossmember Bo l t . . . . . . . . 40 ft. lbs. Crossmember Mounting B olts........................... 25 ft. lbs. Oil Cooler L ine................................................... 10 ft. lbs. Line Pressure Take-Off P lug ............................. 13 ft. lbs. Strainer Retainer Bolt ..................................... 10 ft. lbs. Oil Cooler Pipe Connectors to Transmission C ase.................................................................. 28 ft. lbs. Oil Cooler Pipe to C o n n ecto r........................... 10 in. lbs. Downshift Switch to B rack et............................. . 22 in. lbs. TR U CK SU PP — SPECS SPECIFICATIONS 22 STEERING SECTION 9 STEERING GEAR RATIOS M A N U A L STEERING GEAR Pow er M anual Components G 1 0 -3 0 Thrust Bearing Preload 6 to 11 C1p103° P20 - 30 K10 - 20 V e h ic le G ear R a tio O v e ra ll R a tio 24:1 29.4:1 to 36.7:1 17.5:1 24:1 29.4:1 to 36.4:1 17.5:1 21.4:1 to 26.5:1 P10 24:1 29.1:1 to 35.5:1 17.5:1 21.2:1 to 25.7:1 P20-30 24:1 29.1:1 to 35.3:1 17.5:1 21.2:1 to 25.7:1 G 10-20 G30 M otor Home - C 10 C20-30 14:1 - O v e ra ll R a tio 21.4:1 to 26.7:1 16.0:1 to 21.9:1 24:1 29.1:1 to 37.0:1 16:1 to 13:1 16.9:1 to 20.2:1 24:1 29.4:1 to 36.3:1 16:1 to 13:1 17.2:1 to 20.6:1 24:1 K 10-20 G ear R a tio 24.6:1 to 28.0:1 16:1 to 13:1 13.2:1 to 17.2:1 lbs. in. Adjuster Plug Lock Nut 9 to 12 lbs. in. 85 lbs. ft. 5 to 11 lbs. in.* Over Center Preload 4 to 6 lbs. in. Over Center Lock Nut 9 to 13 lbs. in.* 4 to 10 lbs. in.* 25 lbs. ft. Total Steering Gear Preload 18 lbs. in. Max. 14 lbs. in. Max. 25 lbs. in. Max. *In excess o f thrust bearing preload. POWER STEERING GEAR Components Steering Gear Ball Drag All C, P, K and G 3 lbs. in. Max. Thrust Bearing Preload 1/2 to 2 lbs. in.* Adjuster Plug Locknut 80 lbs. ft. Over-Center Preload lbs. in. Over-Center Adjusting Screw Locknut 35 lbs. ft. Total Steering Gear Preload 14 lbs. in. Max. *In excess of ball drag. **In excess of ball drag and thrust bearing preload. POWER STEERING PUM P PRESSURES Vehicle Pressure C10-30 1200 - 1300 psi G 10-20 900 - 1000 psi G30 1200 - 1300 psi P10-30 1200 - 1300 psi M otor Home & K 1350 - 1450 psi TRUCK SUPP — SPECS SPECIFICATIONS 23 TORQUE SPECIFICATIONS Component C10-30 G10-30 K10-20 P10-30 M otorHom e Steering W heel Nut 30 ft. lbs. 30 ft. lbs. 30 ft. lbs. 30 ft. lbs. 30 ft. lbs. Turn Signal Lever Screw 20 in. lbs. 20 in. lbs. 20 in. lbs. 20 in. lbs. 20 in. lbs. T ilt W heel Lever 35 in. lbs. 35 in. lbs. 35 in. lbs. 35 in. lbs. 35 in. lbs. 35 in. lbs. — 35 in. lbs. — — Turn Signal Switch Screws 25 in. lbs. 25 in. lbs. 25 in. lbs. 25 in. lbs. 25 in. lbs. Turn Signal Housing Screws 45 in. lbs. — 45 in. lbs. — 45 in. lbs. Lock B olt Spring Screw (Tilt) 35 in. lbs. 35 in. lbs. 35 in. lbs. 35 in. lbs. 35 in. lbs. Bearing Housing Support Screws (Tilt) 60 in. lbs. 60 in. lbs. 60 in. lbs. 60 in. lbs. 60 in. lbs. 120 in. lbs. 120 in. lbs. Ignition Switch Screw Steering Column Bracket Screws — — — Column Support to Column Bracket Stud Nuts 20 ft. lbs. — 20 ft. lbs. — — Column S upport to Column Bolts 23 ft. lbs. — 23 ft. lbs. — — Column to Dash Panel Clamp Screws — 174 in. lbs. — 120 in. lbs. 120 in. lbs. 98 in. lbs. 98 in. lbs. F irewall (Toe Panel) Bracket Clamp Bolt 17 ft. lbs. — Floor Pan Cover Screws 35 in. lbs. — 35 in. lbs. — — Floor Pan Cover Clamp Screws 35 in. lbs. — 35 in. lbs. — — Toe Panel Cover Screws 20 in. lbs. 30 in. lbs. 20 in. lbs. Low er Coupling to W orm shaft Clamp Bolt 30 ft. lbs. 30 ft. lbs. 30 ft. lbs. Upper and Low er Univesal J o in t Clamp — Low er Bearing Adjusting Ring Bolt — Upper Steering Shaft Clamp — Low er M ast Jacket Bearing Clamp Bolt — — 70 in. lbs. — 17 ft. lbs. 25 in. lbs. — 43 in. lbs. — — 75 ft. lbs. 75 ft. lbs. — 70 in. lbs. 70 in. lbs. — 18 ft. lbs. 18 ft. lbs. — 34 ft. lbs. 48 ft. lbs. Flexible Coupling Stud Nuts 20 ft. lbs. 18 ft. lbs. 20 ft. lbs. — Steering Gear M ounting Bolt Nuts 65 ft. lbs. 110 ft. lbs. 65 ft. lbs. 65 ft. lbs. 65 ft. lbs. 30 ft. lbs. 30 ft. lbs. Steering Gear Support Reinforcem ent Bolts — — — 18 ft. lbs. TR U CK SUPP — SPECS SPECIFICATIONS 24 TORQUE SPECIFICATIONS Component C10-30 G10-30 K10-20 P10-30 MotorHom e Tie Rod End Stud Nuts 45 ft. lb s.* 45 ft. lb s.* 45 ft. lb s.* 45 ft. lb s.* 45 ft. lbs * Pitman Shaft Nut 185 ft. lbs. 185 ft. lbs. 90 ft. lbs. 185 ft. lbs. 125 ft. lbs. Idler Arm to Frame Bolts 30 ft. lbs. 30 ft. lbs. — 30 ft. lbs. 30 ft. lbs. Idler Arm to Relay Rod Stud Nut 60 ft. lbs. 70 ft. lbs. — 60 ft. lbs. 60 ft. lbs. Pitman Arm to Relay Rod Nut 60 ft. lbs. 70 ft. lbs. — 60 ft. lbs. 60 ft. lbs. Pitman Arm to Idler Support Arm Nut — — — 125 ft. lbs. 125 ft. lbs. Relay Support Assem bly to Frame Nut — — — 48 ft. lbs. 48 ft. lbs. Steering Connecting Rod Nuts — — 50 ft. lbs. 70 ft. lbs. 70 ft. lbs. A Steering Connecting Rod Clamp Nuts — — 40 ft. lbs. Tie Rod Clamp Bolt Nuts 22 ft. lbs. 22 ft. lbs. 22 ft. lbs. — — 22 ft. lbs. 22 ft. lbs. A bsorber to Axles Stud Nut — — 80 ft. lbs. — — A b sorber to Tie Rod Stud Nut — — 45 ft. lb s.* — — Power Steering Pump M ounting Bracket Bolts (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. Power Stering Pump M ounting Bolts (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. Power Steering Pump M ounting Stud Nut (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. (L-6) 18 ft. lbs. (V-8) 25 ft. lbs. Power Steering Hose Clamp Screws 15 in. lbs. 15 in. lbs. 15 in. lbs. 15 in. lbs. 15 in. lbs. Power Steering Gear Hose Fittings 25 ft. lbs. 25 ft. lbs. 25 ft. lbs. 25 ft. lbs. 165 in. lbs. 150 in. lbs. 150 in. lbs. ------ Power Steering Hose Clamp Nut 150 in. lbs. Power Steering Hose Clip Nut 150 in. lbs. Oil Cooler to Radiator Support 30 in. lbs. — 150 in. lbs. 150 in. lbs. — — — — 18 ft. lbs. — Reservoir Attaching Screws — — — — 15 in. lbs. Reservoir Hose Clamp Screws — — — — 150 in. lbs. *P lus a d d itio n a l to rq u e re q u ire d to align ca s te lla tio n w ith c o tte r p in h o le in stud (n o t to exceed 6 0 f t . lbs. m a x im u m ) ± P lu s a d d itio n a l to rq u e re q u ire d to align ca s te lla tio n w ith c o tte r p in hole in stu d (n o t to exceed 100 f t . lbs. m a x im u m ) TR U CK SU PP — SPECS SPECIFICATIONS 25 W HEELS AND TIRES SECTION 10 WHEELS W hee l N ut T o rq u e - 1 0 -3 0 S e rie s SERIES DESCRIPTION K 1 0 , 15 7 / 1 6 " B o lts (6) 7 0 - 90 F t. Lbs. 1 /2 " B o lts (5) 7 5 -1 0 0 Ft. Lbs. C , P 2 0 ,2 5 ,3 0 ,3 5 S in g le W h e e ls 9 / 1 6 " B o lts (8) 9 0 - 1 2 0 F t. Lbs. C , P 2 0 ,2 5 ,3 0 ,3 5 D ual W h e e ls 9 / 1 6 " B o lts (8) H eavy D u ty W h e e ls 5 / 8 " B o lts (10) 1 1 0 -1 4 0 F t. Lbs. 1 3 0 -1 8 0 F t. Lbs. C , P 1 0 , 15 TORQUE SERIES DESCRIPTION G 1 0 , 15 7 / 1 6 " B o lts (6) 5 5 - 75 F t. Lbs. G 2 0 ,2 5 1 /2 " B o lts (5) 7 5 - 1 0 0 F t. Lbs. G 3 0 ,3 5 S in g le W h e e ls 9 / 1 6 " B o lts (8) 9 0 - 1 2 0 F t. Lbs. G 3 0 ,3 5 D ual W h e e ls 9 / 1 6 " B o lts (8) 1 1 0 -1 4 0 F t. Lbs. TORQUE TIRES S ee "M in im u m T ire In fla tio n ” and "T ire Load an d Infla tion P re s s u re ’ ’ C h a rts in S e c tio n 10 of th is M a n u a l. SHEET M ETAL SECTION 11 TORQUE SPECIFICATIONS Lock Support to Hood Lock Bolt Nut Bumper Bolt Nut Hood Hinge Hood Lock Catch Hood Stop Bolt Hood Support Rod Assembly Lock Support to Rad. Support Rad. Support to Frame Radiator Support Bracket to Fender Radiator Support to Fender Rad. Grille Panel Tie Bar Assembly Radiator Support Cover Plate Fender Skirt to Fender Fender to Cowl Fender Skirt to Underbody Fender Skirt Rear Support to Frame Rear Fender to Side Panel Rear Fender Brace to Fender Dual Wheel Fender to Side Panel Running board, Hangers, and Braces 150 30 85 35 150 25 CK in. ft. in. ft. in. ft. lbs. lbs. lbs. lbs. lbs. lbs. 150 35 50 150 150 in. ft. in. in. in. lbs. lbs. lbs. lbs. lbs. G 150 in. 40 ft. 150 in. 18 ft. 18 ft. P lbs. lbs. lbs. lbs. lbs. 85 ft. lbs. 18 ft. lbs. 30 ft. lbs. 90 in. lbs. 150 in . lbs. 35 ft. lbs. 35 ft. lbs. 30 in. lbs. 150 in. lbs. 65 in. lbs. 92 150 150 150 in. in. in. in. lbs. lbs. lbs. lbs. TR U CK SU PP — SPECS SPECIFICATIONS 26 BODY AND CHASSIS ELECTRICAL SECTION 12 FUSES— CIRCUIT BREAKERS The w irin g circuits are protected from short circuits by a com bina­ tion of fuses, circuit breakers, and fusible therm al links in the w iring itself. This greatly reduces the hazard of electrically caused fires in the vehicles. The headlam p circuits are protected by a circuit breaker in the light switch. An electrical overload on the breaker w ill cause the lamps to go on and off. or in some cases to remain off. In addition to a fuse, the w indsh ield w ip e r m otor is also protected by a circuit breaker. If the m otor overheats, due to overloading caused by heavy snow, etc.. the w ipers w ill remain stopped until the m otor cools. Fuses located in the Junction Block beneath the dash on the drivers side are: C-K TRUCK Heater, Front A /C , Generator W arn in g Lamp ................... 2 0 Amp Idle Stop Solenoid, Aux. Battery, Radio, Tim e Delay Re­ lay, Emission Control Solenoid, Transmission D ow nshift (M 4 0 ) ................................................................. 15 Amp C igarette Lighter, Clock, Dome Lamp, Cargo Lamp ....... 2 0 Amp Fuel Gauge, Brake W arn in g Lamp, Tem perature W a rn ­ ing Lamp, Oil Pressure W arn in g Lamp .......................... 4 Amp Heater, A /C ............................................................................... Idle Stop Solenoid, Cruise Control, D irectional Signal Lamp, D irectional Signal Indicator Lamp, Transm is­ sion D ow nshift (M 4 0 ) ........................................................ Cigarette Lighter, Dom e Lamp, Spot Lamp ...................... 2 5 amp 10 amp 15 amp Fuel Gauge, Brake W arning Lamp, Tem perature W a rn ­ ing Lamp, Generator W arning Lamp, Oil Pressure W arning Lamp ...................................................................... 3 amp Stop Lamp, Traffic Hazard ...................................................... 1 5 amp Auxiliary Battery, Backing Lamp, Radio Dial Lamp, Radio ....................................................................................... 15 amp Instrum ent Cluster Lamp, Heater Dial Lamp, Transm is­ sion Control Lamp w ith Tilt W heel, Cruise Control Lamp, W /S W iper S w itch Lamp, Headlam p Buzzer ... 3 amp License Lamp, Parking Lamp, Side M arker Lamp Tail Lamp ....................................................................................... 15 amp W indshield W iper ..................................................................... 25 amp An in-Line fuse is located in the A m m e ter and the auxiliary heater circuits. Do not use fuses of higher amperage rating than those recommended above. Courtesy Lamp, Roof M arker Lamp, License Plate Lamp, Parking Lamp, Side M arker Lamp, Tail Lamp, C lear­ ance Lamp ............................................................................ 20 Amp D irectional Signal Indicator Lamp, Stop Lamp, Traffic Hazard .................................................................................... 1 5 Amp Instrum ent Cluster Lamp, Heater Dial Lamp, Radio Dial Lamp, Cruise Control Lamp, W indshield W iper S w itch Lamp ...................................................................................... W indshield W ip e r/W a s h e r G TRUCK The following wiring harnesses are protected by a "fusible link" which is a special wire incorporated in the circuit; ignition, horn and headlamp hi-beam indicator circuits. Should an electrical overload occur, this wire will fail and prevent damage to the major harness. 4 Amp ................................................... 25 Amp Cruise Control, Rear W in d o w , Aux. Fuel Tank, Tachom e­ ter, Back-up Lamp, D irectional Signal Indicator Lamp, Directional Signal Lamp, Headlamp Buzzer ................. 1 5 Amp CIRCUIT BREAKERS P TRUCK H eaterf. A ir C o n d itio n in g ! .................................................... 25 Amp Instrument Cluster Lamp, W indshield W iper S w itch Lamp ...................................................................................... 3 Amp Directional Signal Indicator Lamp, Stop Lamp, Traffic Hazard .................................................................................... 1 5 Amp Fuel Gauge, Brake W arning Lamp ....................................... Device or circuit protected Models Amperes Location Headlamp and parking lamp circuit C -K-P-G 15 Light sw itch Tailgate w in d o w m otor C-K Dash 3 0 (forw ard side) G Dash (forw ard side) 3 Amp Rear A /C (C69overhead) License Plate Lamp, Parking Lamp, Side M arker Lamp, Tail Lamp, Clearance Lamp, Identification Lamp ....... 1 5 Amp W indshield W a s h e r/W ip e r ................................................... 25 Amp Cigarette Lighterf. C lockf. Courtesyt. Dome Lamp (• ...... 1 5 Amp Auxiliary B atteryf, Back-up Lamp, Radio ........................... 1 5 Amp Idle Stop Solenoid, Cruise C o n tro lf. D irectional Signal Lamp. Time Delay Relay, Emission Control Solenoid, Transmission D ow nsh ift (M 4 0 ) ........................................ 10 Amp In -lin e fuses are located in the auxiliary heater circuits (C.-K-P m o d ­ els) and underhood lamp, fro n t and rear A /C circuits (C-K models). fW h e n incorporated by body builder. Do not use fuses of higher amperage than those recommended above. The following wiring harnesses are protected by a "fusible link" which is a special wire incorporated in the circuit: headlamp hi-beam indicator, horn and ignition circuits (C-K-P models); starter solenoid (pull-in and hold) circuit (C-K models). Should an electrical over­ load occur, this wire will fail and prevent damage to the major harness. TRUCK SU PP — SPECS SPECIFICATIONS 27 LA M P BULB DATA LAM P BULB D ATA C -K -P TRUCK G TRU CK Q uantity Trade Used in # Power Dome lamps: Cab 1 1003 15 CP B lazer, J im m y & S ubu rban 1 21 1 -2 12 CP 1 168 3 CP Oil Pressure indica tor la m p 1 Generator indica tor la m p 1 Instrum ent cluster lam ps2 Headlamp beam indicator lamp Lamp assembly — tail & stop lamp 1 168 3 CP 5 168 3 CP 1 168 3 CP 2 1 157 3 - 3 2 CP License lam p4 1 67 4 CP Directional signal (front park lamps)6 2 1 157 3 - 3 2 CP Head Lamps 2 6014 5 0 -6 0 W Tem perature indica tor lamp 1 168 3 CP D irectional signal indica tor lamp 2 168 3 CP Clearance and m arker lamps 4 168 3 CP Roof m arker lamps5 5 194 Used in Q uantity Trade # Power Dome lamps 2 2 1 1 -2 12 CP Oil pressure indicator lamp 1 168 3 CP Generator indicator lamp 1 168 3 CP Instrum ent cluster lamps 3 168 3 CP Headlamp beam indicator lamp 1 168 3 CP Park, directional signal lamps 2 1 1 57 3 - 3 2 CP Tail, stop lamps 2 1 157 3 - 3 2 CP License lamp 1 67 4 CP Head Lam ps1 2 6014 Temperature Indicator Lamp 1 168 3 CP Directional signal indicator lamp 2 168 3 CP M arker lamps 4 16 8 3 CP 5 0 -6 0 W Brake w arn ing indicator lamp 1 168 3 CP Back-up lamp 2 1 15 6 32 CP Radio dial lamp 1 1893 2 CP 2 CP Brake W arning Indicator 1 168 3 CP Transmission Control 1 1445 0 .7 CP Backing lamp 2 1 15 6 32 CP H eater or A /C 1 1445 0 .7 CP Corner m arker lamps 7 67 4 CP Cargo lamp 1 1 142 21 CP 1 1816 3 CP 1 216 1 CP Cruise Control lamp 1 53 1 CP Courtesy lamp 1 1003 15 CP W indshield w ip e r sw itch 1 161 1 CP 1 16 8 3 CP 10 1895 2 CP Heater or A /C Contro, 1 1895 2 CP Transmission C ontrol w /T ilt W heel 1 1445 0 .7 CP Cruise control 1 53 1 CP W /S w ip e r sw itch lamp 1 161 1 CP 1Double filament sealed beam 60W high beam, 50W low beam. Radio Dial lamp — A M - A M /F M Clock Rear Ide n tific a tio n 7 U nderhood lamp 1 93 15 CP Seat belt w arn ing 1 168 3 CP C arg o/do m e lamp 2 2 1 1 -2 12 CP 1 On CA, KA 1 0 -3 5 instrument clusters only. 2 3 lamps used on instrument cluster on P models or C -K w /o gauges. ^ Double filament sealed beam 60W high beam, 50W low beam. 4 2 lamps used with step bumper and P models. ® 4 required on P models. 6 1157 NA, 2 .2 -2 4 CP on C-K models. 7 Wideside Pickup. 1976 TR U CK SUPP — SPECS SPECIFICATIONS 28 R A D IA T O R AND G R IL L E SECTION 13 TORQUE SPECIFICATIONS CK - Grille to Tie Bar 12 Grille Grille B racket to R adiator Support 50 in. lbs. - F an Guard Coolant Recovery T ank B rk t. - 96 in . lbs.(bolts) 50 in . lbs.(screw s) - Hose Clamps R adiator M ounting Panel - 42 in . lbs. 96 in . lbs. 30 i n . lb s . 112 D rain Plug R adiator M ounting B racket and Brace (Motor Home) in . lbs. 96 in. lbs. 1 5 0 in. lbs. F an Shroud P G 23 in . lbs. 112 17 in . lbs. in . lbs. 17 in. lbs. 150 in. lbs. 18 f t. lbs. To R adiator To F ram e in . lbs. - 120 in . lbs. P(32) 50 in . lbs. P(42) 28 in . lbs. 112 in . lbs. 18 in . lbs. 150 in . lbs. - 150 in . lbs. 25 f t. lbs. - 35 f t. lbs. - R adiator Support B racket To F ram e - R adiator Baffle - R adiator Baffle Seal R etainer - 150 in . lbs. R adiator M ounting Strap - 150 in . lbs.(u p p er) 30 f t. lbs.(low er) Filler Neck Support - - 85 in . lbs. Support B racket to R adiator support - — 42 in . lbs. 96 in . lbs. BUMPERS S E C TIO N 1 4 TORQUE SPECIFICATIONS C, P AND K Front B um per.................................................................... ..35 ft. lbs. Front Bumper Bracket and B r a c e ............................... 70 ft. lbs. Rear Bumper to Outer B racket..................................... ..35 ft. lbs. Rear Bumper Outer Bracket and Brace .................... 50 ft. lbs. License Plate B r a ck et...................................................... ..18 ft. lbs. Gravel D e f le c t o r .................................................................85 in. lbs. Rear Step Bumper to Bracket or F r a m e .................... 40 ft. lbs. TORQUE SPECIFICATIONS G Front Face Bar to B r a ck et........................................ 24 ft. lbs. Bracket to Cross S i l l ....................................................... 24 ft. lbs. License Plate Bracket to Face B a r ................................100 in. lbs. Rear Face Bar to Brackets ...............................................55 ft. lbs. Bracket to Floor ................................................................ 55 ft. lbs. ACCESSORIES SECTION 15 CRUISE-MASTER Solenoid R esista n ce........................................................................................................................................................................ 5 ohms ± 1 / 4 ohm Solenoid Wire R e sista n c e .............................................................................................................................................................................. 40 ohms Maximum allowable Vacuum Leakage rate for Servo u n i t ..................................................................... 5 inches o f Vacuum Per Minute Not Greater than 1 inch o f Vacuum per 10 seconds Operational Test S p e e d ...................................................................................................................................................................................... 55 MPH TR U CK SUPP — SPECS CHEVROLET