INSUFFICIENT HEATER PERFORMANCE. Chevrolet Chevy G Van 1991

SUBJECT: INSUFFICIENT HEATER PERFORMANCE (INSTALL NEW WATER PUMP AND RE-ROUTE HEATER OUTLET HOSE)

MODELS: 1990-94 CHEVROLET AND GMC TRUCK G VANS WITH 5.0L AND 5.7L ENGINES (VINS H, K - RPOS L03, L05)

CONDITION:

SOME CUSTOMERS MAY COMMENT ON INSUFFICIENT HEAT DURING COLD WEATHER OPERATIONS. THE HEATING SYSTEM MAY BE PERFORMING PROPERLY; HOWEVER, THE CUSTOMER MAY STILL BE DISSATISFIED.

CAUSE:

INADEQUATE WARM UP TIME FROM THE HEATING SYSTEM. IN EXTREME COLD ENVIRONMENTS, THE HEATING SYSTEM MAY BE UNSATISFACTORY IF THE VEHICLE IS EQUIPPED WITH ONLY A FRONT HEATING SYSTEM. IT MAY BE NECESSARY TO INSTALL A SECOND (REAR) HEATING SYSTEM.

CORRECTION:

INSTALL A NEW WATER PUMP WHICH WILL NEED A 1 INCH LONG STEEL NIPPLE, AND RE-ROUTE THE HEATER OUTLET HOSE TO THE NEW WATER PUMP. THIS WILL IMPROVE THE WARM UP TIME FOR THE HEATING SYSTEM.

SERVICE PROCEDURE:

BEFORE INSTALLING THE NEW WATER PUMP AND RE-ROUTING THE HEATER OUTLET HOSE, MAKE SURE THAT THE HEATING SYSTEM IS FUNCTIONING PROPERLY. THERE ARE A VARIETY OF OPTIONS WHICH MAY EFFECT THE HEATING PERFORMANCE.

FIRST, PERFORM A FUNCTION TEST. BEFORE PERFORMING THE FUNCTION TEST, MAKE SURE THAT THE ENGINE COOLANT IS HOT AND THERMOSTAT IS OPEN. THIS FUNCTION TEST PROCEDURE IS LOCATED IN THE SERVICE MANUAL SECTION 1A.

CHECK AND VERIFY THAT THE FOLLOWING ITEMS ARE FUNCTIONING PROPERLY. IF NOT, REPAIR AS NEEDED USING THE SERVICE MANUAL SECTION 1A.

- LOW COOLANT - ACTUATOR MODE DOOR (TEMPERATURE LEVER) - THERMOSTAT - WATERFLOW OBSTRUCTIONS - AIRFLOW OBSTRUCTIONS - BLOWER MOTOR ASSEMBLY

IF THE HEATING SYSTEM CHECKS OUT TO BE FUNCTIONING NORMALLY, INSTALL THE NEW WATER PUMP (PRESENTLY USED ON 4.3L ENGINES) AND REROUTE THE HEATER OUTLET HOSE FROM THE RADIATOR TO THE WATER PUMP ASSEMBLY.

REMOVAL PROCEDURE:

1. DRAIN COOLANT (REFERENCE SERVICE MANUAL SECTION 6B1). 2. REMOVE WATER PUMP ASSEMBLY (REFERENCE SERVICE MANUAL SECTION 6B1). 3. REMOVE THE HEATER OUTLET HOSE. THERE ARE 2 METHODS OF ROUTING. REFERENCE (FIGURE #1) FOR THE OLD ROUTING. ONCE THE HOSE HAS BEEN REMOVED, IT WILL BE NECESSARY TO SAVE APPROXIMATELY 3 INCHES OF HOSE MATERIAL. THIS WILL ALLOW THE RADIATOR SIDE OF THE CONNECTION TO BE PLUGGED.

INSTALLATION PROCEDURE:

1. INSTALL STEEL NIPPLE TO WATER PUMP. BEFORE INSTALLING THE STEEL NIPPLE, SEAL THREADS WITH PIPE SEALANT (P/N 12346004) OR EQUIVALENT. TORQUE TO 24 N.M (18 LBS. FT.) 2. INSTALL WATER PUMP, (REFERENCE SERVICE MANUAL SECTION 6B). 3. INSTALL END CAP PLUG INTO REMAINING HOSE AND INSTALL ONTO THE RADIATOR. FASTEN SECURELY WITH HOSE CLAMPS. 4. INSTALL NEW HEATER OUTLET HOSE ROUTING IT TO THE WATER PUMP (FIGURE #2). FASTEN SECURELY WITH HOSE CLAMPS. MAKE SURE THAT THE HOSE HAS A CLEAN ROUTING. MAKE SURE THAT THE HOSE DOES NOT RUB OR CONTACT ANY SHARP EDGES. SECURE WITH TIE WRAPS IF APPLICABLE. 5. INSTALL REMAINING ACCESSORIES. 6. FILL COOLANT TO NORMAL OPERATING LEVELS. START ENGINE AND INSPECT FOR LEAKS. 7. PERFORM FUNCTION TEST. VERIFY THAT COOLANT LEVELS ARE AT NORMAL OPERATING LEVELS, ENGINE HOT AND THERMOSTAT IS OPEN. 8. CHECK THE COOLANT LEVELS ONE MORE TIME. FILL TO OPERATING LEVELS IF APPLICABLE.

SERVICE PARTS INFORMATION:

P/N DESCRIPTION QTY 12522032 WATER PUMP ASSEMBLY 1 15685705 HOSE ASSY. W/C60-C36/YF7, -C36/C60 1 15990531 HOSE ASSY. W/C36, OR W/YF7-C36 1 10235669 STEEL NIPPLE 1 12346004 PIPE SEALANT AS REQUIRED 15975492 END CAP PLUG 1 10108254 CLAMP 3

PARTS ARE EXPECTED TO BE AVAILABLE FROM GMSPO ON 11/14/94.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OP DESCRIPTION LABOR TIME J3480 WATER PUMP - REPLACE USE PUBLISHED LABOR OPERATION TIME

ADD REROUTE HOSE W/O AIR CONDITIONING .3 HRS ADD REROUTE HOSE W/AIR CONDITIONING 1.7 HRS

FIGURES: 2

CAPTIONS: FIGURE 1 - CURRENT HEATER OUTLET HOSE ROUTING FIGURE 2 - NEW HEATER OUTLET HOSE ROUTING

Object Number: 84882 Size: FS

Object Number: 82867 Size: FS

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.