MISCELLANEOUS DIESEL INFO. MULTIPLE SUBJECTS

THIS BULLETIN CONTAINS MULTIPLE SUBJECTS. PAGE THROUGH TO DESIRED SUBJECT.

A. USE OF STARTER FLUIDS IN DIESEL ENGINES

THIS IS TO ADVISE THAT STARTER FLUIDS SUCH AS EITHER OR OTHER SUCH START- ING AIDS MUST NOT BE USED IN DIESEL ENGINES. USE OF THESE FLUIDS CAN CAUSE SEVERE INTERNAL ENGINE DAMAGE.

WE ASK THAT THE ABOVE INFORMATION BE BROUGHT TO THE ATTENTION OF OWNERS AND THOSE IN YOUR DEALERSHIP RESPONSIBLE FOR WORKING ON OR MOVING DIESEL DIESEL EQUIPPED VEHICLES.

B. CYLINDER BLOCK AND BEARING BOLT CHANGES FOR DIESEL AND LV2 (5.0L) ENGINES

A NEW 1/4" LONGER BEARING CAP BOLT P/N 22511818, IS REPLACING P/N 392190, FOR BOTH GAS AND DIESEL CYLINDER BLOCKS. ALL (10) HOLES IN THE DIESEL BLOCK HAVE A 1/4" DEEPER TAP AND A 1/4" LONGER COUNTER BORE. THE GAS BLOCK HAS THE DEEPER TAP AND COUNTER BORE AT NO. 5 BEARING CAP LOCATION ONLY. THE CHANGES BEGAN WITH THE 1981 START OF PRODUCTION.

C. 1981 DIESEL CYLINDER HEAD GASKET

DUE TO DOWEL PIN LOCATION ON EARLY 1981 DIESEL ENGINES IT IS POSSIBLE TO INSTALL THE CYLINDER HEAD GASKET UP SIDE DOWN. ENGINEERING IS ADDING A DOWEL PIN TO THE CYLINDER BLOCK TO PREVENT INCORRECT INSTALLATION OF CYLINDER HEAD GASKETS. ON ALL DIESEL ENGINES THE PRECHAMBER SHIELD ON THE HEAD GASKET MUST BE INSTALLED TOWARDS CYLINDER HEAD.

D. DIESEL FAST GLOW RELAY PRECAUTION

THE DIESEL ENGINE FAST GLOW CONTROL SYSTEM REQUIRES THE USE OF A HEAVY DUTY CONTROL RELAY, P/N 560580. THIS RELAY IS MOUNTED TO THE RH FILLER PLATE AND CONTROLS THE FLOW OF CURRENT FROM THE BATTERY TO THE GLOW PLUGS

THE GLOW PLUG RELAY MUST NOT BE BYPASSED FOR ANY REASON. JUMPING THE RELAY TO ENERGIZE THE GLOW PLUGS BYPASSES THE INTERNAL CIRCUITRY THAT CONTROLS THE TEMPERATURE RELATIONSHIP AT THE PLUGS. THIS ACTION WILL CAUSE THE GLOW PLUGS TO BURN OUT.

E. VALVE LIFTER BLEED DOWN PROCEDURE

A NEW VALVE LIFTER BLEED DOWN PROCEDURE HAS BEEN DEVELOPED FOR ALL 1981 DIESEL ENGINES. IF THE ROCKER ARMS HAVE BEEN LOOSENED OR REMOVED THE VALVE LIFTER CAN BE BLED DOWN BY THE FOLLOWING PROCEDURE:

1. BEFORE INSTALLING ANY REMOVED ROCKER ARMS, ROTATE THE ENGINE CRANK- SHAFT TO A POSITION OF NO. 1 CYLINDER BEING 32 DEG. BEFORE TOP DEAD CENTER. THIS IS 13MM (1/2") BEYOND THE END OF THE TIMING INDICATOR. IT MAY BE NECESSARY TO REMOVE NO. 1 CYLINDER GLOW PLUG TO DETERMINE IF THE POSITION OF THE PISTON IS CORRECT. THE COMPRESSION PRESSURE WILL TELL YOU THAT YOUR ARE IN THE RIGHT POSITION.

NOTICE: USE ONLY HAND TOOLS TO TORQUE THE ROCKER ARM PIVOT BOLTS TO AVOID ENGINE DAMAGE.

2. IF REMOVED, INSTALL THE NO. 5 CYLINDER PIVOT AND ROCKER ARMS. TORQUE THE BOLTS ALTERNATELY BETWEEN THE INTAKE AND EXHAUST VALVES UNTIL THE EXHAUST VALVE BEGINS TO OPEN, THEN STOP.

3. INSTALL REMAINING ROCKER ARMS BUT WATCH NO. 3 AND NO. 8 INTAKE VALVES (IF THESE ROCKER ARMS WERE REMOVED) AS THE PIVOT BOLTS ARE BEING TORQUED.

4. DO NOT TORQUE NO. 3 AND NO. 8 INTAKE VALVE PIVOTS BEYOND THE POINT THAT THE VALVE WOULD BE FULLY OPEN. THIS IS INDICATED BY STRONG RE- SISTANCE WHILE STILL TURNING THE PIVOT RETAINING BOLTS. GOING BEYOND THIS WILL BEND THE PUSH ROD. TORQUE THE BOLTS SLOWLY ALLOWING THE LIFTER TO BLEED DOWN.

5. FINISH TORQUING NO. 5 CYLINDER ROCKER ARM PIVOT BOLTS SLOWLY. DO NOT GO BEYOND THE POINT THAT THE VALVE WOULD BE FULLY OPEN. THIS IS IN- DICATED BY STRONG RESISTANCE WHILE STILL TURNING THE PIVOT RETAINING BOLTS. GOING BEYOND THIS WILL BEND THE PUSH ROD.

6. DO NOT TURN THE ENGINE CRANKSHAFT FOR AT LEAST 45 MINUTES.

7. FINISH REASSEMBLING THE ENGINE AS THE LIFTERS ARE BEING BLED.

NOTICE: DO NOT ROTATE THE ENGINE UNTIL THE VALVE LIFTERS HAVE BEEN BLED DOWN, OR DAMAGE TO THE VALVE TRAIN COULD OCCUR.

F. PURGING AIR FROM INJECTION PUMP

THIS INFORMATION WILL REDUCE THE TIME REQUIRED TO PURGE AIR FROM THE IN- JECTION PUMP WHICH REDUCES STARTING TIME.

WHEN CHANGING THE FUEL FILTER OR WHEN THE CAR HAS RUN OUT OF FUEL, DIS- CONNECT THE CONNECTOR FROM THE TEMPERATURE SWITCH AND JUMPER CONNECTOR TERMINALS. THIS WILL AID IN PURGING AIR FROM THE PUMP. (THIS PROCEDURE IS NECESSARY ONLY ON A HOT ENGINE, AS THE CIRCUIT WILL ALWAYS BE CLOSED WHEN THE ENGINE IS COLD.)

G. ENGINE OIL FILTER RECOMMENDATION

THE RECOMMENDED SERVICE REPLACEMENT ENGINE OIL FILTER FOR ALL 1981 DIESEL ENGINES IS PF45 WHICH IS THE SAME FILTER RECOMMENDED FOR 1980.

INFORMATION IN EARLY 1981 OWNER'S MANUAL IS INCORRECT.

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.