CAMPAIGN: 6.2L DIESEL ENGINE OIL FILLER CAP REPLACE

GENERAL MOTORS HAS DETERMINED THAT SOME 1983-1984 G-VANS AND P MODEL LIGHT DUTY TRUCKS EQUIPPED WITH A 6.2L DIESEL ENGINE (RPO LH6/LL4) MAY EXPERIENCE CRANKCASE DEPRESSION REGULATOR VALVE (CDR) RESTRICTION OR PLUGGING. THE CRANKCASE DEPRESSION REGULATOR VALVE ON THE 6.2L DIESEL MAINTAINS A NEGATIVE PRESSURE IN THE CRANKCASE BY DRAWING AIR OUT OF THE OIL FILLER TUBE. WATER VAPORS AND VENT GASES PRESENT IN THE CRANKCASE CONDENSE IN THE VENT HOSE. THIS CONDENSATE (WATER-OIL MIXTURE) COLLECTS AT THE LOW POINT OF THE VENTILATION SYSTEM, WHICH IS THE INLET TUBE OF THE CDR VALVE. IN EXTREMELY COLD AMBIENTS THIS CONDENSATE FREEZES AND RESTRICTS OR PLUGS THE VENTILATION SYSTEM. THIS ALLOWS THE CRANKCASE PRESSURE TO INCREASE FORCING OIL OUT OF THE ENGINE CAUSING A MAJOR ENGINE FAILURE REQUIRING REPLACEMENT OF THE ENGINE. TO PREVENT THE POSSIBILITY OF THIS CONDITION OCCURRING DURING BELOW FREEZING TEMPERATURES, A NEW DESIGN OIL FILLER CAP, WITH A PRESSURE RELIEF VALVE, SHOULD BE INSTALLED. SINCE AN OIL FILLER CAP CAN BE EASILY INSTALLED, AND TO REDUCE OWNER INCONVENIENCE, NEW OIL CAPS HAVE BEEN SENT DIRECTLY TO OWNERS OF RECORD OWNERS MAY INSTALL THE NEW CAP OR THEY MAY ASK A DEALER TO DO THE SERVICE. DEALER SERVICE IS TO BE DONE AT NO CHARGE TO OWNERS. VEHICLES INVOLVED INVOLVED ARE ALL 1983 AND CERTAIN 1984 G-VANS AND "P" MODEL LIGHT DUTY TRUCKS EQUIPPED WITH A 6.2L DIESEL ENGINE (RPO LH6/LL4). SERVICE PROCEDURE INSTALL A NEW OIL FILLER CAP, PART NO. 25060118 (IDENTIFIED AS SHOWN IN FIGURE NO. 1), ON EACH INVOLVED VEHICLE. PARTS INFORMATION PARTS REQUIRED TO COMPLETE THIS CAMPAIGN WILL BE MAILED TO THE OWNERS OF RECORD AND TO INVOLVED DEALERS BY GMC TRUCK. ADDITIONIAL CAMPAIGN PARTS CAN BE OBTAINED BY CONTACTING YOUR ZONE OFFICE. DO NOT ORDER PARTS FROM WDDGM. TO COMPLETE VEHICLES IN YOUR INVENTORY, THE $ AMOUNT IDENTIFIED IN THE "PARTS ALLOWANCE" COLUMN BELOW REPRESENT 30% OF DEALER NET FOR PARTS THAT WERE FURNISHED BY GMC TRUCK. THIS AMOUNT IS TO BE PLACED IN THE NET ITEM AMOUNT COLUMN OF THE CLAIM AND USE TYPE CODE "M". QUANTITY PART NUMBER DESCRIPTION PARTS ALLOWANCE PER VEHICLE 25060118 OIL FILLER CAP $ 1 DISCARD FORMER OIL FILLER CAP. ON CERTAIN P MODELS, IT WILL NOT BE POSSIBLE TO INSTALL THE NEW OIL FILLER CAP. TO CORRECT THIS CONDITION IT WILL BE NECESSARY TO REPOSITION THE OIL FILLER TUBE TO PROVIDE ADEQUATE CLEARANCE AS FOLLOWS. 1. DISCONNECT NEGATIVE BATTERY CABLES. P-MODEL VALUE VANS OR FORWARD CONTROL CHASSIS ONLY: 2. REMOVE NUTS RETAINING THE OIL FILLER TUBE LOWER HOLD-DOWN BRACKET (SEE FIGURE NO. 2). REMOVE AND DISCARD UPPER BRACKET IF EQUIPPED. REINSTALL NUT ON CROSSOVER MANIFOLD, IF UPPER BRACKET WAS REMOVED, AND TORQUE TO 18-27 NM (13-20 FT.-LBS.). 3. INSTALL SPACERS (5/16" FLAT WASHERS) AS REQUIRED ON THE LOWER HOLD-DOWN BRACKET ATTACHING STUDS (SEE FIGURE NO. 3). APPROXIMATELY ONE INCH OF CLEARANCE IS NEEDED AT THE OIL FILLER CAP. 4. REINSTALL OIL FILLER TUBE (WITH NEW OIL FILLER CAP) AND HOLD-DOWN BRACKET. ADDITIONAL CLEARANCE, NEEDED CAN BE GAINED BY FIRMLY PULLING ON THE FILLER TUBE. THIS WILL SLIGHTLY DISTORT THE HOLD DOWN BRACKET. CARE SHOULD BE USED WHEN DOING THIS, HOWEVER, SO THAT THE FILLER TUBE IS NOT DAMAGED NOR THE OIL SEAL GROMMET. P-MODEL MOTOR HOMES ONLY: 5. REMOVE OIL FILL TUBE CLAMPS (FIGURE NO. 4). 6. SEPARATE OIL FILL TUBE FROM HOSE. 7. SHORTEN OIL TUBE ABOUT 1-1/2 INCHES. REMOVE BURRS AND ANY METAL SHAVINGS FROM TUBE. 8. REATTACH TUBE TO HOSE. 9. REPOSITION TUBE (WITH NEW OIL FILLER CAP INSTALLED) TO PROVIDE ADEQUATE CLEARANCE. 10. REINSTALL TUBE USING REAR CLAMP ONLY, INSTALLED IN THE SAME LOCATION ON THE OIL FILL TUBE SUPPORT BRACKET. DISCARD FRONT CLAMP. ALL P-MODELS: 11. RECONNECT NEGATIVE BATTERY CABLE.

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.