CAMPAIGN: AIR BRAKE RESERVOIR CHECK VALVE MAY FAIL

DEFECT INVOLVED GENERAL MOTORS HAS DETERMINED THAT A DEFECT WHICH RELATES TO MOTOR VEHICLE SAFETY EXISTS IN SOME 1983 C6, C7 AND P6 MEDIUM DUTY TRUCKS EQUIPPED WITH AIR BRAKES (RPO JE4). SOME TRUCKS WERE BUILT WITH A CARBON STEEL SPRING INSTALLED IN THE DUAL AIR RESERVOIR TANK CHECK VALVE, INSTEAD OF THE SPECIFIED STAINLESS STEEL SPRING. IN THIS APPLICATION, THE CARBON STEEL SPRING COULD RUST AND ALLOW THE CHECK VALVE TO FAIL. IF AN AIR LEAK WERE TO DEVELOP IN THE REAR PRIMARY BRAKE SYSTEM, A FAILED CHECK VALVE COULD RESULT IN COMPLETE LOSS OF THE FRONT AND REAR SERVICE BRAKE SYSTEMS. IF AN AIR LEAK WERE TO OCCUR, A LOW PRESSURE WARNING BUZZER AND LIGHT WOULD ALERT THE DRIVER TO THE LOSS OF THE SERVICE BRAKE SYSTEM. IF THE DRIVER WERE TO FAIL TO HEED THESE WARNINGS, A VEHICLE CRASH COULD OCCUR. DEALERS ARE TO INSPECT EACH TRUCK, AS DESCRIBED IN THE SERVICE PROCEDURE, TO DETERMINE THE CORRECTION PROCEDURE REQUIRED. VEHICLES INVOLVED INVOLVED ARE CERTAIN 1983 C6, C7 SINGLE OR TANDEM REAR AXLE AND P6T042 MEDIUM DUTY MODEL TRUCKS EQUIPPED WITH AIR BRAKES (RPO JE4). CHECK THE C.R.I.S. SYSTEM TO DETERMINE IF A SPECIFIC VEHICLE IS INVOLVED IN THE CAMPAIGN. INSPECTION PROCEDURE 1. INSPECT EACH TRUCK TO DETERMINE IF EQUIPPED WITH A DUAL COMPARTMENT AIR RESERVOIR TANK (SEE FIGURE NO. 1). IF TRUCK IS NOT EQUIPPED WITH A DUAL COMPARTMENT AIR RESERVOIR TANK NO FURTHER ACTION IS REQUIRED. 2. IF TRUCK IS EQUIPPED WITH A DUAL COMPARTMENT AIR RESERVOIR TANK, INSPECT TANK FOR JOHNSON MANUFACTURING TRADEMARK AND DATE CODE (SEE FIGURE NO. 1). IF MAY BE NECESSARY TO REMOVE FOREIGN MATERIAL AND PAINT WITH SUITABLE CLEANER OR ABRASIVE TO READ STAMPED TRADEMARK AND DATE CODE. IF TRUCK IS NOT EQUIPPED WITH A JOHNSON DUAL COMPARTMENT AIR RESERVOIR TANK, IDENTIFIED BY THE JOHNSON MANUFACTURING TRADEMARK, NO FURTHER ACTION IS REQUIRED. 3. TRUCKS EQUIPPED WITH JOHNSON MANUFACTURING DUAL COMPARTMENT AIR RESERVOIR TANKS THAT HAVE A STAMPED DATE CODE WITHIN AND INCLUDING THE FOLLOWING BUILD DATE CODES REQUIRE CHECK VALVE ASSEMBLY REPLACEMENT. FROM THROUGH 10-26-82 6-15-83 SERVICE PROCEDURE 1. BLOCK VEHICLE WHEELS. 2. DRAIN ALL AIR RESERVOIRS TO 0 PSI (0 KPA). 3. REMOVE THE CAP FROM THE CHECK VALVE (REFERENCE FIGURE NOS. 1 AND 2). BE CAREFUL IN DOING THIS AS THE CAP COMPRESSES THE SPRING AND RUBBER BALL. 4. REMOVE AND DISCARD SPRING, WASHER AND RUBBER BALL (SEE FIGURE NO. 2). CLEAN VALVE SEAT AREA. 5. REASSEMBLE USING PARTS FROM CHECK VALVE REPAIR KIT, P/N 15529164, (FIGURE NO. 2). TORQUE CAP TO 55-65 FT. LBS. (75-88 NM). 6. BUILD UP AIR PRESSURE IN BRAKE SYSTEM AND TURN ENGINE OFF. NOTE AIR PRESSURE ON AIR PRESSURE GAGE IN THE INSTRUMENT PANEL, IT SHOULD READ APPROXIMATELY 120 PSI (827 KPA). 7. DEPLETE THE AIR PRESSURE IN THE SUPPLY SIDE OF THE AIR RESERVOIR TANK, CLOSE DRAIN PORT OF TANK (SEE FIGURE NO. 1) AND WAIT 15 MINUTES. 8. AGAIN NOTE PRESSURE READING ON AIR PRESSURE GAGE. THE AIR PRESSURE ON GAGE SHOULD AGAIN READ APPROXIMATELY 120 PSI (827 KPA). NEXT SLOWLY OPEN THE DRAIN PORT ON THE AIR RESERVOIR TANK AND LISTEN FOR ANY AIR ESCAPE. IF THERE IS AIR LEAKAGE, THE CHECK VALVE SHOULD BE RECHECKED FOR PROPER ASSEMBLY, FIGURE NO. 2, AND STEPS 6, 7 AND 8 OF THE PROCEDURE REPEATED. NOTICE: ALWAYS MAKE SURE THAT THE BRAKES ARE OPERATIONAL AFTER PERFORMING BRAKE WORK AND BEFORE RETURNING THE VEHICLE TO SERVICE. PARTS INFORMATION PARTS ARE TO BE OBTAINED FROM THE WAREHOUSING AND DISTRIBUTION DIVISION OF GENERAL MOTORS (WDDGM). TO ENSURE THAT THESE PARTS WILL BE OBTAINED AS SOON AS POSSIBLE, THEY SHOULD BE ORDERED FROM WDDGM ON A C.I.O. ORDER WITH NO SPECIAL INSTRUCTION CODE, BUT ORDER ON AN ADVISE CODE (2). TRUCKS REQUIRING REPLACEMENT OF THE DUAL AIR RESERVOIR TANK CHECK VALVE ASSEMBLY WILL NEED THE FOLLOWING REPAIR KIT: PART NUMBER QUANTITY PER VEHICLE DESCRIPTION 15529164 1 CHECK VALVE REPAIR KIT 1 STAINLESS STEEL SPRING 1 RUBBER CHECK BALL 1 WASHER

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.