BLUE SMOKE ON START-UP (REPLACE VALVE STEM SEALS). GMC Truck S15 Pickup

********************************************************************* SUBJECT: BLUE SMOKE ON START-UP (REPLACE VALVE STEM SEALS)

MODELS: 1985-90 CHEVROLET CAPRICE WITH 4.3L (LB4) ENGINE 1985-93 CHEVROLET AND GMC C/K, G, M/L, S/T, AND P TRUCKS WITH 4.3L ENGINE 1991-93 OLDSMOBILE BRAVADA WITH 4.3L ENGINE ********************************************************************* CONDITION: SOME OWNERS MAY COMMENT THAT THEY OBSERVE BLUE SMOKE COMING FROM THE TAILPIPE OF THEIR VEHICLE IMMEDIATELY AFTER THEY START THEIR ENGINE. THE CONDITION GENERALLY OCCURS AFTER THE VEHICLE HAS BEEN PARKED FOR SEVERAL HOURS.

CAUSE:

OIL LEAKING DOWN THE VALVE STEM(S) INTO THE CYLINDER(S) AFTER THE ENGINE IS SHUTDOWN. WHEN THE ENGINE IS RESTARTED, THE OIL THAT HAS LEAKED INTO THE CYLINDER IS IGNITED, CAUSING THE BLUE SMOKE.

CORRECTION:

REPLACE ALL INTAKE AND EXHAUST VALVE STEM SEALS. USE THE V8 UMBRELLA STYLE EXHAUST VALVE STEM SEAL. THE UMBRELLA STYLE SEAL IS RECOMMENDED FOR SERVICE BECAUSE IT IS EASIER TO INSTALL THAN THE O-RING STYLE EXHAUST VALVE STEM SEAL USED IN PRODUCTION. BARREL STYLE SEALS CONTINUE TO BE USED ON THE INTAKE VALVE (SAME AS PRODUCTION). FOLLOW THE PROCEDURE PUBLISHED IN THE APPROPRIATE SERVICE MANUAL FOR VALVE STEM SEAL REPLACEMENT.

WARNING: IMPROPER SEAL INSTALLATION MAY CAUSE A CONDITION WORSE THAN THE ORIGINAL CONCERN.

PARTS INFORMATION:

NUMBER DESCRIPTION PART NUMBER REQUIRED ----------- ----------- -------- VITON EXHAUST VALVE STEM SEAL 10147882 6 INTAKE VALVE STEM SEAL 460483 6

4.3L LB4 HEAVY DUTY (GREATER THAN 8500 GVW) VITON EXHAUST VALVE STEM SEAL 10147883 6 INTAKE VALVE STEM SEAL 460483 6

PARTS ARE CURRENTLY AVAILABLE FROM GMPSO.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE: LABOR OPERATION: J0547 USE PUBLISHED LABOR OPERATION TIME.

FIGURES: 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.