ENGINE NOISE (INSTALL VALVE STEM OIL SEAL). Chevrolet Impala 1995

REVISION: 03/13/97

THIS BULLETIN IS BEING REVISED TO INCLUDE THE 1997 MODEL YEAR FOR TRUCKS. A NEW PRODUCTION EXHAUST VALVE STEM OIL SEAL IS EXPECTED TO BE IN ALL 1997 VEHICLES BY THE END OF THE MODEL YEAR. PLEASE DISCARD CORPORATE BULLETIN NUMBER 67-61-14 (SECTION 6 - ENGINE). ----------------------------------------------------------------------

REVISION: 08/29/97

THIS BULLETIN IS REVISED TO INCLUDE THE W4 TRUCK MODEL FOR CHEVROLET AND GMC TRUCKS. PLEASE DISCARD CORPORATE BULLETIN NUMBER 67-61-14A (SECTION 6 - ENGINE). ----------------------------------------------------------------------

SUBJECT: ENGINE NOISE (INSTALL VALVE STEM OIL SEAL)

MODELS: 1994-96 BUICK ROADMASTER 1994-96 CADILLAC FLEETWOOD 1994-96 CHEVROLET CAPRICE, IMPALA SS WITH 4.3L, 5.7L V8 ENGINE (VINS W, P - RPOS L99, LT1)

1996-97 CHEVROLET AND GMC C/K, M/L, S/T, G, P AND W4 TRUCKS 1996-97 OLDSMOBILE BRAVADA 1997 ISUZU WITH 4.3L V6 AND 5.0L, 5.7L V8 ENGINE (VINS M, R, W, X - RPOS L30, L31, L35, LF6)

CONDITION:

SOME OWNERS MAY COMMENT ABOUT A RHYTHMIC ENGINE NOISE AT IDLE. THE NOISE, WHICH OCCURS AT HALF ENGINE SPEED, HAS BEEN DESCRIBED AS A "WHOOP-WHOOP" (SIMILAR TO A HELICOPTER IDLING), AN ENGINE RATTLE NOISE (NOT TO BE CONFUSED WITH PVC RATTLE), A LIFTER TICK IN THE LOWER END, A BALANCE SHAFT NOISE, OR A ROD KNOCK.

WHEN USING A STETHOSCOPE, THE NOISE WILL SOUND AS COMING FROM DEEP WITHIN THE ENGINE. THE NOISE MAY BE HEARD IN THE PASSENGER COMPARTMENT AND IN S/T VEHICLES IS AUDIBLE AT THE CATALYTIC CONVERTER AND TAIL PIPE.

IMPORTANT: THE NOISE WILL GET LOUDER AS THE ENGINE WARMS UP AT IDLE.

THE NOISE DOES NOT DIMINISH WITH REMOVAL OF THE ACCESSORY DRIVE BELT, BALANCE SHAFT GEAR, OR DISCONNECTING THE TORQUE CONVERTER.

CAUSE:

THE NOISE MAY BE CAUSED BY A LOW LEVEL OF LUBRICATION ON THE EXHAUST VALVE STEM, CREATING A 'SLIP-STICK' CONDITION BETWEEN THE VALVE STEM AND VALVE GUIDE.

CORRECTION:

1996 VEHICLES EQUIPPED WITH A 4.3L V6 ENGINE (RPOS L35, LF6) SHOULD BE CHECKED TO SEE IF CAMPAIGN 96-C-17 (EXCESSIVE OIL CONSUMPTION) APPLIES AND HAS BEEN PERFORMED TO THE VEHICLE BEING SERVICED. VEHICLES IDENTIFIED IN THE CAMPAIGN SHOULD HAVE THE CAMPAIGN PERFORMED BEFORE THEY ARE REPAIRED FOR A 'WHOOP NOISE' CONDITION.

INSTALL THE VALVE STEM OIL SEAL LISTED BELOW, ON THE EXHAUST VALVE GUIDES ONLY.

LIGHTLY LUBRICATE THE SEAL, AND WITH FINGER PRESSURE ONLY, PUSH IT ON TO THE VALVE STEM AND DOWN ON TO THE EXHAUST VALVE GUIDE. (SEE FIGURE 1)

IMPORTANT: DO NOT INSTALL THIS SEAL ON INTAKE VALVE GUIDES. THIS SEAL IS NOT RELEASED FOR INTAKE VALVE APPLICATION IN THE ABOVE IDENTIFIED VEHICLES.

NEW ROCKER COVER GASKETS MAY BE REQUIRED.

FIGURE 1

PARTS INFORMATION:

PARTS ARE AVAILABLE FROM GMSPO AS FOLLOWS:

QUANTITY ENGINE DESCRIPTION REQUIRED PART NO. ______ ___________ ________ ________ V6-1996-97 OIL SEAL 6 460483 L35 AND LF6 ROCKER COVER SEAL 2 10201397

V8-1996-97 OIL SEAL 8 460483 L30 AND L31 ROCKER COVER GASKET 2 10046089 1994-96 LT1 (IRON HEAD) L99

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR LABOR LABOR VEHICLE OPERATION CODE TIME _______ _________ _____ _____ B,D SEAL, VALVE- J-0547 USE C,K REPLACE PUBLISHED M,L TIMES S,T P,G,W4

FIGURES: 1 ATTACHMENTS: 0 FIGURE 1 - 1 - VALVE STEM OIL SEAL 2 - VALVE GUIDE 3 - VALVE STEM

Object Number: 93549 Size: MF

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.