INCREASED OIL CONSUMPTION (REPLACE VALVE ROCKER. Chevrolet Cavalier 1998

REVISION: 03/03/98

THIS BULLETIN IS BEING REVISED TO ADD ADDITIONAL TEXT. ______________________________________________________________________

SUBJECT: INCREASED OIL CONSUMPTION (REPLACE VALVE ROCKER ARM COVER)

MODELS: 1998 CHEVROLET CAVALIER 1998 PONTIAC SUNFIRE

1998 CHEVROLET AND GMC S MODELS 1998 ISUZU HOMBRE WITH 2.2L ENGINE (VIN 4 - RPO LN2) BUILT PRIOR TO OCTOBER 27, 1997

CONDITION:

SOME CUSTOMERS MAY COMMENT ABOUT INCREASED OIL CONSUMPTION AND HAVING TO ADD OIL BETWEEN OIL CHANGES.

CAUSE:

ON ENGINES BUILT BEFORE OCTOBER 27, 1997, VALVE ROCKER ARM COVER BAFFLE DESIGN MAY NOT BE ABLE TO CONTROL OIL FLOW INTO THE FOUL AIR SIDE OF THE CRANKCASE VENTILATION SYSTEM UNDER CERTAIN CONDITIONS. IN ADDITION, DURING SOME HIGH RPM OPERATION OF THE ENGINE, OIL MAY BE FORCED INTO THE AIR CLEANER DUCT AND PREPLENUM ASSEMBLY.

CORRECTION:

INSTALL A NEW ROCKER ARM COVER GM P/N 24577253 USING PROCEDURES OUTLINED IN THE APPROPRIATE SERVICE MANUAL.

SERVICE PROCEDURE:

1. IF THE OWNER OF THE VEHICLE EXPRESSES CONCERN WITH OIL CONSUMPTION, REVIEW THE OIL CONSUMPTION RATE AND, IF NECESSARY, PERFORM AN OIL CONSUMPTION TEST ON THE VEHICLE. PERFORM AN OIL CHANGE, NOTE THE MILEAGE AND ALLOW THE OWNER TO DRIVE THE VEHICLE FOR A SUFFICIENT NUMBER OF MILES FOR THE ENGINE TO CONSUME **ONE QUART** OF OIL. AT THE END OF THE TEST, REVIEW THE OIL CONSUMPTION RATE. CONSUMPTION OF MORE THAN 1 QUART (.946L) WITHIN 2000 MILES (3200 KM) SHOULD BE ADDRESSED.

2. REVIEW THE ENGINE BROADCAST CODE LABEL. THE BROADCAST CODE LABEL IS LOCATED ON THE INTAKE MANIFOLD ON TRUCKS AND ON THE VALVE ROCKER ARM COVER ON CARS. ACROSS THE BOTTOM OF THE LABEL THERE WILL BE A SEQUENCE OF LETTERS AND NUMBERS STARTING WITH THE LETTER "T." THE FIRST FIVE NUMBERS IN THE SEQUENCE CORRESPOND TO THE ENGINE BUILD DATE STARTING WITH THE CALENDAR YEAR; FOR EXAMPLE T **7 10 27** 0001 = OCTOBER 27, 1997. ANY ENGINE BUILT ON OR AFTER OCTOBER 27, 1997, ALREADY HAS THE REVISED COVER IN PLACE AND THIS BULLETIN DOES NOT APPLY.

3. INSPECT THE VALVE ROCKER ARM COVER FOR AN IDENTIFICATION MARK (SEE FIGURE 1). THE MARK WILL BE LOCATED ON THE REAR (TRANSMISSION) END OF THE VALVE ROCKER ARM COVER TOWARD THE INTAKE MANIFOLD SIDE OF THE ENGINE. IF THE VEHICLE ALREADY HAS A VALVE ROCKER ARM COVER WITH THIS IDENTIFICATION MARK, **DO NOT REPLACE THE VALVE ROCKER ARM COVER**. IF THE VEHICLE HAS A CONCERN WITH INCREASED OIL CONSUMPTION, REVIEW THE CONDITIONS LISTED IN STEP 5 OF THIS BULLETIN AND PROCEED WITH DIAGNOSTICS IN THE ENGINE SECTION OF THE APPROPRIATE SERVICE MANUAL.

IMPORTANT: ALWAYS CHECK ENGINE OIL ON A LEVEL SURFACE, BE SURE THAT THE ENGINE HAS BEEN RUN UNTIL IT HAS REACHED OPERATING TEMPERATURE AND THAT THE ENGINE HAS BEEN OFF FOR AT LEAST 5 MINUTES TO ALLOW FOR PROPER OIL DRAIN-DOWN. IF OIL CONSUMPTION IS GREATER THAN THAT LISTED ABOVE, PROCEED WITH STEP 4.

4. INSTALL A REVISED VALVE ROCKER ARM COVER GM P/N 24577253 USING PROCEDURES OUTLINED IN THE ENGINE MECHANICAL SECTION OF THE APPROPRIATE SERVICE MANUAL.

5. IF THE OWNER OF THE VEHICLE STILL HAS A CONCERN WITH ENGINE OIL CONSUMPTION AFTER IT HAS BEEN DETERMINED THAT THE LATEST DESIGN COVER IS INSTALLED, PERFORM FURTHER INSPECTION OF ENGINE COMPONENTS FOR ITEMS THAT MAY CAUSE INCREASED OIL CONSUMPTION AND REPAIR AS NECESSARY. POSSIBLE CAUSES OF INCREASED OIL CONSUMPTION INCLUDE THE FOLLOWING CONDITIONS:

* EXTERNAL OIL LEAKS * INCORRECT OIL LEVEL OR IMPROPER READING OF OIL LEVEL INDICATOR * IMPROPER OIL VISCOSITY * CONTINUOUS HIGH SPEED DRIVING AND/OR SEVERE USAGE SUCH AS TOWING, OR DRIVING IN MOUNTAINOUS TERRAIN * BLOCKED CYLINDER HEAD, CYLINDER HEAD GASKET, OR ENGINE BLOCK OIL DRAIN HOLES * VALVE GUIDES AND/OR VALVE STEM OIL SEALS WORN, OR THE SEAL OMITTED * PISTON RINGS BROKEN, IMPROPERLY INSTALLED, MISSING, WORN, OR NOT SEATED PROPERLY * PISTONS IMPROPERLY INSTALLED OR IMPROPERLY FITTED

PARTS INFORMATION:

DESCRIPTION PART NUMBER ----------- ----------- COVER, VALVE ROCKER ARM 24577253

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION:

FOR VEHICLES UNDER WARRANTY, USE:

LABOR OPERATION LABOR OPERATION NUMBER DESCRIPTION TIME --------------- ----------- --------------- J0308 COVER AND/OR GASKET. 0.5 HOURS ROCKER - REPLACE; J CAR

J0308 COVER AND/OR GASKET. 0.8 HOURS ROCKER - REPLACE; S TRUCK

FIGURES: 01 ATTACHMENTS: 00

Object Number: 452167 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.