WHITE SMOKE ON COLD START COLD WEATHER RECOMMENDATIONS. Chevrolet Chevy MD Conventional (C Model) 1990

SUBJECT: COLD START-UP ABOVE NORMAL WHITE SMOKE OR STUCK EXHAUST VALVES/CATERPILLAR 3116 DIESEL ENGINE COLD WEATHER RECOMMENDATIONS MODELS: 1990-91 C6H AND C7H TOPKICK/KODIAK MEDIUM DUTY TRUCKS WITH CAT 3116 ENGINES (RPO - LX0)

THERE HAVE BEEN OCCASIONAL REPORTS OF ABOVE NORMAL WHITE SMOKE AND STUCK EXHAUST VALVES/BENT PUSH RODS ON THE MODELS LISTED ABOVE. A COMBINATION OF COLD TEMPERATURE, HEAVY FUEL, AND NOT OPERATING THE ENGINE LONG ENOUGH TO REACH NORMAL OPERATING TEMPERATURE CAN CAUSE DEPOSITS TO FORM ON THE EXHAUST VALVES OF SOME OF THESE DIESEL ENGINES. THESE "TAR LIKE" DEPOSITS ON THE EXHAUST VALVE STEMS MAY CAUSE THE VALVES TO STICK IN THE CLOSED POSITION AND RESULT IN BENT PUSHRODS.

SEVERAL ITEMS SHOULD BE ADDRESSED IN CASES WHERE A VEHICLE HAS STUCK AN EXHAUST VALVE/BENT A PUSH ROD OR A CUSTOMER IS COMPLAINING OF ABOVE NORMAL WHITE SMOKE. THE FOLLOWING SERVICE PROCEDURE SHOULD BE UTILIZED IN NORTHERN OR HIGH-ALTITUDE CLIMATES THAT REGULARLY HAVE WINTER TEMPERATURES OF 0 DEGREES C (32 DEGREES F) OR LOWER.

ACTION ITEMS:

1) REPLACE THE EXHAUST VALVE PUSH RODS WITH STRONGER PUSH RODS (IF THE ENGINE IS NOT EQUIPPED WITH STRONGER PUSH RODS). THE STRONGER PUSH RODS CAN BE IDENTIFIED BY THEIR 3 PIECE DESIGN (WELDED BALL AND SOCKET) VERSUS A ONE PIECE DESIGN FOR THE OLD STYLE ROD.

2) REMOVE THE EXHAUST VALVE SEALS ON 215 AND 250 HP ENGINES (FIGURE 1).

3) ADVANCE THE FUEL TIMING BY 2.5 DEGREES ON THE 215 AND 250 HP ENGINES. VERIFY CORRECT ENGINE TIMING ON THE 165, 170 AND 185 HP ENGINES.

4) THE HEATER RETURN HOSE SHOULD BE REPLUMBED FROM THE THE RADIATOR END TANK TO A PORT ON THE WATER PUMP (FIGURE 2).

5) INSTALL A WINTER FRONT THAT CAN BE OPENED IN THE SAME FASHION AS THE ILLUSTRATED WINTER FRONT (FIGURE 3).

CAUTION:

INSTALLATION OF A WINTER FRONT IN A CONFIGUATION OTHER THAN THAT SPECIFIED IN THE FOLLOWING PAGES MAY CAUSE FAN OR FAN CLUTCH DAMAGE WHICH COULD RESULT IN PERSONAL INJURY.

THE ACTION ITEMS LISTED ABOVE ARE DETAILED IN THE FOLLOWING TWO SERVICE PROCEDURES. THE FIRST PROCEDURE IS FOR VEHICLES EXHIBITING EXCESSIVE WHITE SMOKE AND WITHOUT STUCK EXHAUST VALVE. THE SECOND PROCEDURE IS FOR VEHICLES WITH STUCK EXHAUST VALVE(S).

SERVICE PARTS NEEDED

CAT PART NUMBER DESCRIPTION QUANTITY ---------------- ------------ -------- 4P4324 PUSH ROD 6 9Y8103 GASKET 1 9Y7355 WASHER 6 3K0360 O-RING 1

GM PART NUMBER DESCRIPTION QUANTITY -------------- ----------- -------- *15544596 CAP 1 *1470030 CLAMP 1

* PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

PROCURE LOCALLY:

SAE NUMBER 8 FITTING - 3/4" X 16 STRAIGHT THREADS WITH A 5/8" HOSE NIPPLE

SERVICE PROCEDURE FOR VEHICLES THAT EXHIBIT ABOVE NORMAL WHITE SMOKE WITHOUT STUCK EXHAUST VALVES:

NOTE: CATERPILLAR RELEASED A PRODUCT SUPPORT PROGRAM ON A SERVICE LETTER DATED OCTOBER 20, 1990 (PS4530). THIS PROGRAM CAN BE ADMINISTERED BEFORE OR AFTER A CONDITION OCCURRENCE. IT IS RECOMMENDED THAT THIS PREVENTIVE ACTION NEED ONLY BE ADMINISTERED IN NORTHERN OR HIGH-ALTITUDE CLIMATES THAT REGULARLY HAVE WINTER TEMPERATURES OF 0 DEGREES CELSIUS (32 DEGREES FAHRENHEIT) OR LOWER. IT IS ALSO RECOMMENDED THAT IT BE ADMINISTERED IF THE PUSHRODS ARE REMOVED OR IF THE ENGINE IS DISASSEMBLED FOR ANY OTHER REASON. PLEASE REFER TO THE CATERPILLAR SERVICE LETTER FOR FURTHER ADMINISTRATIVE INFORMATION.

AFFECTED PRODUCT - STRONGER PUSH RODS

IMPORTANT: MOST 1990 TOPKICK/KODIAK EQUIPPED WITH 3116 ENGINES WERE BUILT WITH STANDARD PUSH RODS, AND ARE CANDIDATES FOR STRONGER PUSH RODS. PLEASE REFER TO THE CAT SERVICE LETTER DATED OCTOBER 20, 1990 (PS4530) FOR A COMPLETE LISTING OF ENGINE SERIAL NUMBERS INVOLVED.

1. REMOVE THE VALVE COVER.

2. ROTATE CRANKSHAFT AND PIN THE FLYWHEEL AT TDC. REFER TO THE TESTING AND ADJUSTING SECTION OF THE 3116 DIESEL ENGINE REPAIR MANUAL GM FORM NO. X-9059. SEE "FINDING TOP CENTER POSITION FOR NUMBER 1 PISTON".

3. REMOVE THE ROCKER ARMS FOR THE THREE EXHAUST VALVES THAT ARE CLOSED.

NOTE: IF THE VEHICLE IS EQUIPPED WITH THE STRONGER EXHAUST VALVE PUSH RODS (STRONGER EXHAUST VALVE PUSH RODS ARE NOTICEABLY LARGER THAN THE INTAKE VALVE PUSH RODS) DO NOT REPLACE THE EXHAUST VALVE PUSH RODS.

A) IF THE NUMBER 1 CYLINDER IS ON TDC OF THE COMPRESSION STROKE REMOVE THE ADJUSTING SCREWS FROM EXHAUST ROCKER ARMS FOR CYLINDERS NUMBER 1, NUMBER 3, AND NUMBER 5.

B) IF THE NUMBER 1 CYLINDER IS ON TDC OF THE EXHAUST STROKE, REMOVE THE ADJUSTING SCREWS FROM EXHAUST ROCKER ARMS FOR CYLINDERS NUMBER 2, NUMBER 4, AND NUMBER 6.

4. REMOVE THE EXHAUST VALVE GUIDE SEALS ON THE THREE EXPOSED EXHAUST VALVES (FIGURE 1).

5. INSTALL A WASHER (CAT NUMBER 9Y7355) BETWEEN THE SPRING AND THE HEAD THIS WASHER IS NECESSARY TO MAINTAIN PROPER SPRING LOAD.

6. REMOVE THE THREE EXHAUST PUSH RODS AND INSTALL THREE NEW PUSH RODS. LUBRICATE BOTH ENDS OF EACH NEW PUSH ROD WITH CLEAN ENGINE OIL BEFORE INSTALLATION. MAKING CERTAIN EACH PUSH ROD IS CORRECTLY INSTALLED (LOCATED) IN THE VALVE LIFTER.

7. INSTALL THE ROCKER ARMS FOR THE THREE CLOSED EXHAUST VALVES.

8. ADJUST THE VALVE CLEARANCE FOR THESE THREE CYLINDERS.

9. ROTATE THE CRANKSHAFT 360 DEGREES (ONE REVOLUTION) AND PIN THE FLYWHEEL AGAIN.

10. REPEAT STEPS (3) THROUGH (8) FOR THE THREE REMAINING EXHAUST VALVE PUSH RODS AND SEALS.

11. CHECK THE VALVE ADJUSTMENT AGAIN AFTER ROTATING THE ENGINE TWO (2) FULL REVOLUTIONS AND PINNING AT TDC. CHECK THE VALVE ADJUSTMENT ON 3 CYLINDERS. ROTATE THE ENGINE ONE MORE REVOLUTION, PIN AT TDC AGAIN AND CHECK THE VALVE ADJUSTMENT ON THE OTHER 3 CYLINDERS.

12. ADVANCE THE FUEL TIMING BY 2.5 DEGREES ON THE 215 AND 250 HP ENGINES. REFER TO CATERPILLAR'S TECHNICAL INFORMATION BULLETIN; COMPONENT CODE: 0373, DATED NOVEMBER 21, 1990. VERIFY CORRECT ENGINE TIMING ON THE 165, 170 AND 185 HP ENGINES.

13. INSTALL THE VALVE COVER.

IMPORTANT: BE SURE TO REMOVE THE BOLT USED TO "PIN" THE FLYWHEEL AND INSTALL THE PLUG IN THE OPENING.

14. REMOVE THE CAB HEATER RETURN HOSE FROM THE RADIATOR END TANK AND PLUG THE END TANK NIPPLE WITH A CAP, GM PART NUMBER 15544596. CLAMP THE CAP TO THE NIPPLE WITH GM PART NUMBER 1470030.

15. INSTALL A FITTING (STRAIGHT OR ELBOW - DEPENDING ON APPLICATION) IN ONE OF THE TWO LARGE SAE NUMBER 8 STRAIGHT-THREAD O-RING PORTS ON THE RIGHT-HAND SIDE OF THE WATER PUMP. THESE ARE 3/4" X 16 STRAIGHT THREADS, WITH A CAT NUMBER 3K0360 O-RING. THE FITTING WILL REQUIRE A 5/8" HOSE CONNECTION ON THE OTHER END. DO NOT PLUMB TO THE SAE NUMBER 8 WATER PUMP DISCHARGE PORT IN THE ALUMINUM PUMP COVER (FIGURE 2).

16. INSTALL A WINTER FRONT THAT CAN BE OPENED IN THE SAME FASHION AS ILLUSTRATED IN (FIGURE 3).

- THE FRONT SHOULD HAVE THE ABILITY TO BE OPENED IN A VEE SHAPE FROM TOP CORNERS TO CENTER GRILL EMBLEM.

- THE FRONT SHOULD BE FASTENED TO THE HOOD AND COVER THE ENTIRE GRILL, INCLUDING COVERING THE GAP AROUND THE GRILL BETWEEN THE EDGES OF THE GRILL AND THE HOOD.

WINTER FRONT USAGE GUIDE:

- FULLY CLOSED BELOW -18 DEGREE C (0 DEGREE F).

- PARTIALLY OPEN FROM -18 DEGREE C TO 0 DEGREE C (0 DEGREE F TO +32 DEGREE F).

- FULLY OPENED OR REMOVED ABOVE 0 DEGREE C (+32 DEGREE F).

NOTE: THE ENGINE COOLANT TEMPERATURE CAN BE USED AS AN INDICATION OF WHEN THE WINTER FRONT SHOULD BE OPENED OR REMOVED. THE COOLANT TEMPERATURE SHOULD NOT BE ALLOWED TO EXCEED THE NORMAL OPERATING TEMPERATURE (82 DEGREE C 180 DEGREE F) WITH THE FRONT CLOSED, BECAUSE THE INLET TEMPERATURE MAY BE TOO HIGH.

REPAIR PROCEDURE FOR ENGINES WITH STUCK EXHAUST VALVES

NOTE: REFER TO THE 1990 MEDIUM TRUCK DIESEL ENGINE REPAIR MANUAL, FORM X-9059, FOR DETAILED DISASSEMBLY AND ASSEMBLY PROCEDURES.

1. REMOVE CYLINDER HEAD FROM ENGINE.

2. REMOVE ALL VALVES, SPRINGS, RETAINERS AND VALVE SEALS FROM CYLINDER HEAD.

3. CLEAN ALL COMPONENTS THOROUGHLY TO REMOVE DEPOSITS.

4. THOROUGHLY CLEAN THE EXHAUST VALVE GUIDES.

5. ASSEMBLE CYLINDER HEAD WITHOUT THE EXHAUST VALVE GUIDE SEALS (FIGURE 1). USE A WASHER, CAT PART 9Y7355 IN PLACE OF THE EXHAUST VALVE GUIDE SEALS. LUBRICATE VALVE STEMS/GUIDES WITH CLEAN ENGINE OIL.

6. INSTALL THE CYLINDER HEAD ON ENGINE USING STRONGER EXHAUST VALVE PUSH RODS CAT PART 4P4324.

7. ADVANCE THE FUEL TIMING BY 2.5 DEGREES ON THE 215 AND 250 HP ENGINES. REFER TO CATERPILLAR'S TECHNICAL INFORMATION BULLETIN; COMPONENT CODE: 0373, DATED NOVEMBER 21, 1990. VERIFY CORRECT ENGINE TIMING ON THE 165, 170 AND 185 HP ENGINES.

8. REMOVE THE CAB HEATER RETURN HOSE FROM THE RADIATOR END TANK AND PLUG THE END TANK NIPPLE WITH A CAP, GM PART NUMBER 15544596. CLAMP THE CAP TO THE NIPPLE WITH GM PART NUMBER 1470030.

9. INSTALL A FITTING (STRAIGHT OR ELBOW - DEPENDING ON APPLICATION) IN ONE OF THE TWO LARGE SAE NUMBER 8 STRAIGHT-THREAD O-RING PORTS THE RIGHT-HAND SIDE OF THE WATER PUMP. THESE ARE 3/4" X 16 STRAIGHT THREADS, WITH A CAT NUMBER 3K0360 O-RING. THE FITTING WILL REQUIRE A 5/8" HOSE CONNECTION ON THE OTHER END. DO NOT PLUMB TO THE SAE NUMBER 8 WATER PUMP DISCHARGE PORT IN THE ALUMINUM PUMP COVER (FIGURE 2).

10. CHANGE CRANKCASE OIL AND FILTER. IF THE UNIT IS EQUIPPED WITH A LUBERFINER, BE SURE TO DRAIN AND REFILL THE LUBERFINER ALSO. REFER TO THE OPERATION AND MAINTENANCE MANUAL FOR OIL SPECIFICATIONS AND CAPACITIES.

11. DYNO TEST OR OPERATE TRUCK UNDER LOADED CONDITIONS TO CLEAN OUT DEPOSITS FROM THE EXHAUST SYSTEM.

12. INSTALL A WINTER FRONT THAT CAN BE OPENED IN THE SAME FASHION AS ILLUSTRATED IN (FIGURE 3).

- THE FRONT SHOULD HAVE THE ABILITY TO BE OPENED IN A VEE SHAPE FROM TOP CORNERS TO CENTER GRILL EMBLEM.

- THE FRONT SHOULD BE FASTENED TO THE HOOD AND COVER THE ENTIRE GRILL, INCLUDING COVERING THE GAP AROUND THE GRILL BETWEEN THE EDGES OF THE GRILL AND THE HOOD.

WINTER FRONT USAGE GUIDE:

- FULLY CLOSED BELOW -18 DEGREE C (0 DEGREE F).

- PARTIALLY OPEN FROM -18 DEGREE C TO 0 DEGREE C (0 DEGREE F TO +32 DEGREES F).

- FULLY OPENED OR REMOVED ABOVE 0 DEGREE C (+32 DEGREE F)

NOTE: THE ENGINE COOLANT TEMPERATURE CAN BE USED AS AN INDICATION OF WHEN THE WINTER FRONT SHOULD BE OPENED OR REMOVED. THE COOLANT TEMPERATURE SHOULD NOT BE ALLOWED TO EXCEED THE NORMAL OPERATING TEMPERATURE (82 DEGREE C 180 DEGREE F) WITH THE FRONT CLOSED, BECAUSE THE INLET TEMPERATURE MAY BE TOO HIGH.

SUGGESTIONS FOR OPERATING IN COLD WEATHER CONDITIONS (BELOW 32 DEGREES F)

BASED ON THE INFORMATION AVAILABLE, THE FOLLOWING LIST OF SUGGESTIONS SHOULD AID IN STARTING AND OPERATING THE TRUCK IN COLD CONDITIONS.

1. USE AN ELECTRIC JACKET WATER (BLOCK) HEATER WHENEVER POSSIBLE IN TEMPERATURES BELOW 0 DEGREE C (+32 DEGREE F). WARMER CYLINDERS RESULT IN REDUCED CRANKING TIME NEEDED TO START, FASTER CRANKING SPEEDS, QUICKER WARM UP TIME, SMOOTHER COMBUSTION, AND LESS WHITE SMOKE. BLOCK HEATER COMPONENTS AVAILABLE FROM GMSPO, REFER TO PAGE 1-21 IN THE ILLUSTRATION SECTION OF THE MEDIUM TRUCK PARTS CATALOGUE (55-C).

2. USE PRESCRIBED STARTING PROCEDURE GIVEN ON PAGES 23-26 OF THE 3116 OPERATION AND MAINTENANCE MANUAL. USE THE "PREHEAT" FEATURE TO AID STARTING.

3. WHEN AIR AND OIL PRESSURES ARE NORMAL, APPLY LOAD AS SOON AS POSSIBLE TO SPEED ENGINE WARM-UP.

4. MINIMIZE IDLING TIME TO MAINTAIN ENGINE AT OPERATING TEMPERATURE. IF EXTENDED IDLING TIME IS NECESSARY, MAINTAIN ENGINE SPEED AT AN INCREASED LEVEL (1000 - 1200 RPM) USING THE HAND THROTTLE, IF EQUIPPED.

5. OPERATE ON LIGHTEST FUEL AVAILABLE.

- API 37 DEGREES OR HIGHER.

- CETANE NUMBER OF 42 OR HIGHER.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.