CLOUDY, STRAWBERRY COLORED PARKING BRAKE FLUID. GMC Truck GMC MD Bus Chassis (B Model) 1996

SUBJECT: CLOUDY, STRAWBERRY-COLORED PARKING BRAKE FLUID (SEAL PARKING BRAKE PUMP AND RESERVOIR)

MODELS: 1993-97 CHEVROLET AND GMC MEDIUM DUTY TRUCKS 1994-97 CHEVROLET AND GMC P3 CHASSIS MODELS WITH ELECTRIC/HYDRAULIC PARKING BRAKE (RPO J71)

CONDITION:

SOME CUSTOMERS MAY COMMENT ABOUT CLOUDY, STRAWBERRY-COLORED PARKING BRAKE FLUID IN THE RESERVOIR.

CAUSE:

THE "O" RING SEAL BETWEEN THE PARKING BRAKE RESERVOIR AND PUMP ASSEMBLY MAY BE ALLOWING MOISTURE IN THE SYSTEM. IN ADDITION, ON P3 CHASSIS, THIS CONDITION MAY BE CAUSED BY THE PRESENCE OF A RED COLORED VENT PLUG THAT SHOULD HAVE BEEN REMOVED AT ASSEMBLY.

CORRECTION:

APPLY RTV SILICONE RUBBER SEALANT BETWEEN THE RESERVOIR AND PUMP ASSEMBLY AND ON P3 CHASSIS MODELS, REMOVE THE PLUG OVER THE VENT HOLE IF PRESENT.

SERVICE PROCEDURE:

1. REMOVE THE COMPONENT BOX TOP IF EQUIPPED (3 BOLTS). 2. REMOVE THE PARKING BRAKE RESERVOIR FROM THE PUMP ASSEMBLY. 3. DRAIN THE FLUID FROM THE RESERVOIR. 4. CLEAN THE RESERVOIR AND THE MATING SURFACE OF THE PUMP USING RESIDUE-FREE OPTIKLEEN(R) GLASS CLEANER, P/N 1051515 (1 QUART), OR ISOPROPYL ALCOHOL, P/N 1051516, OR EQUIVALENT AND ALLOW TO DRY COMPLETELY. 5. APPLY A 1/16" TO 3/32" BEAD OF RTV SILICONE RUBBER SEALANT, P/N 12345739 OR EQUIVALENT, AROUND THE DIAMETER OF THE RESERVOIR WHERE THE "O" RING IS POSITIONED WHEN INSTALLED. 6. USING A PROTECTED FINGER, SMOOTH THE SEALANT UNIFORMLY AROUND THE DIAMETER OF THE RESERVOIR.

IMPORTANT: ALLOW THE SEALER TO CURE EXACTLY 20 MINUTES.

7. WHILE SEALER IS CURING, LOOSEN THE METAL PIPE AT THE ELBOW IN THE PUMP INLET AND DRAIN THE FLUID FROM THE PIPE. THIS PIPE IS ROUTED BETWEEN THE BOTTOM OF THE SOLENOID AND PUMP INLET. 8. RECONNECT THE PIPE AND TORQUE THE PIPE NUT TO 16 N.M (12 LB FT). 9. LOOSEN THE METAL PIPE AT THE ACTUATOR INLET AND AT THE TEE CONNECTOR. 10. ROTATE THE PIPE AND DRAIN IT OF ANY FLUID. THIS PIPE IS ROUTED BETWEEN THE SOLENOID AND ACTUATOR. 11. RECONNECT THE PIPE AND TORQUE THE PIPE NUT TO 16 N.M (12 LB FT). 12. REMOVE THE "O" RING LOCATED BETWEEN THE PUMP AND RESERVOIR AND WASH THE "O" RING IN A HOT SOAPY WATER SOLUTION AND DRY. 13. INSPECT THE "O" RING AND REPLACE IF DAMAGED USING P/N 15156687. 14. REINSTALL THE "O" RING ON THE PUMP. 15. REINSTALL THE RESERVOIR TO THE PUMP. 16. TORQUE THE CAP SCREW TO 5.6 N.M (50 LB IN). 17. THE LOCATING PIN ON THE RESERVOIR SHOULD BE IN THE HOLE OF THE ADAPTER EAR. THE RESERVOIR FILL NECK ORIENTATION SHOULD BE INBOARD, TOWARD THE FRAME RAIL AND FACING TOWARD THE CENTER OF THE COMPONENT BOX.

IMPORTANT: AT THE END OF THE 20 MINUTE CURE TIME, THE PARTS MUST BE REINSTALLED. IF THE SEALER IS ALLOWED TO CURE TOO LONG, IT MAY NOT SEAL PROPERLY.

IMPORTANT: ON P3 CHASSIS MODELS, LOOK FOR A RED VENT PLUG ON THE RESERVOIR. REMOVE THE PLUG IF PRESENT.

18. FILL THE RESERVOIR BETWEEN THE MINIMUM (MIN) AND MAXIMUM (MAX) LINES USING DEXRON(R)-III TRANSMISSION FLUID.

IMPORTANT: DO NOT FILL THE RESERVOIR ABOVE THE MAX INDICATOR LINE.

19. APPLY AND RELEASE THE PARKING BRAKE 3 OR 4 TIMES TO ASSURE PROPER OPERATION. 20. INSPECT FOR LEAKS AND CORRECT AS REQUIRED. 21. RECHECK THE FLUID LEVEL IN THE RESERVOIR AND ADD FLUID IF NECESSARY. 22. IF EQUIPPED, REINSTALL COMPONENT BOX TOP.

PARTS INFORMATION:

P/N DESCRIPTION QTY 1051515 OPTIKLEEN(R) GLASS CLEANER 1 12345739 SEALANT, RTV SILICONE RUBBER 1 15156687 SEAL, "O" RING 1

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OP DESCRIPTION LABOR TIME H3342 RESERVOIR AND/OR 0.5 HR "O" RING - REPLACE

IMPORTANT: LABOR OPERATION IS CODED TO BASE VEHICLE COVERAGE IN THE WARRANTY SYSTEM.

FIGURES: 0

CAPTIONS: 0

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.