KNOCK, RATTLE, OR TAP NOISE FROM THE ENGINE. Buick Century 1994

REVISION: 02/24/97

THIS BULLETIN IS BEING REVISED TO UPDATE WARRANTY INFORMATION, PARTS INFORMATION, AND TO ADD OLDSMOBILE TO THE DIVISIONS INVOLVED. ---------------------------------------------------------------------- REVISION: 06/02/97

THIS BULLETIN IS BEING REVISED TO ADD PLANTS TO THE VIN CHART BELOW FOR CAVALIER AND SUNFIRE, TO ADD A "NOTICE STATEMENT TO STEP THREE (3) OF THE CORRECTION, TO ADD COOLANT FILL INFORMATION. PLEASE DISCARD CORPORATE BULLETIN NUMBER 77-60-01 (SECTION 6--ENGINE). ----------------------------------------------------------------------

SUBJECT: KNOCK, RATTLE, OR TAP NOISE FROM THE ENGINE BEFORE THE ENGINE HAS REACHED OPERATING TEMPERATURE OR UNDER LIGHT LOAD CONDITIONS AT OPERATING TEMPERATURE (REPLACE PISTON AND/OR ROD ASSEMBLIES)

MODELS: 1994-96 BUICK CENTURY 1994-96 CHEVROLET BERETTA, CORSICA 1994-97 CHEVROLET CAVALIER 1994-96 OLDSMOBILE CIERA 1995-97 PONTIAC SUNFIRE

1994-97 CHEVROLET AND GMC S MODELS WITH 2.2L ENGINE (VIN 4 - RPO LN2)

VEHICLES INVOLVED:

INVOLVED ARE CERTAIN 1994 THROUGH 1997 A CAR, J CAR, L CAR, S TRUCKS AND JIMMYS EQUIPPED WITH LN2 ENGINES AND BUILT WITHIN THE FOLLOWING VIN BREAKPOINTS:

YEAR DIVISION MODEL PLANT PLANT THROUGH CODE 1994-97 CHEVROLET S10, LINDEN K VK148640 SHREVEPORT 8 V8135173 CAVALIER GENESYS B VB102655 LANSING C VM120242 RAMOS S VS823899 LORDSTOWN 7 V7538182 1994-96 CHEVROLET CORSICA ALL BERETTA ALL 1994-96 BUICK CENTURY ALL

1994-96 OLDSMOBILE CIERA ALL

1995-97 PONTIAC SUNFIRE GENESYS B VB102655 LORDSTOWN 7 V7538182 RAMOS S VS823899

1994-97 GMC SONOMA LINDEN K VK505368 SHREVEPORT 8 V8511217

IMPORTANT: CANADIAN DEALERS MUST HAVE PRIOR APPROVAL FROM THEIR DISTRICT SERVICE MANAGER FOR EACH INDIVIDUAL ENGINE REPAIR DESCRIBED IN THIS BULLETIN.

CONDITION:

SOME CUSTOMERS MAY COMMENT OF A KNOCK, RATTLE, TAP, OR TICK NOISE FROM THE ENGINE BEFORE THE ENGINE HAS REACHED OPERATING TEMPERATURE. THE NOISE MAY ALSO OCCUR AT OPERATING TEMPERATURE UNDER LIGHT LOAD OR DECELERATION CONDITIONS. THIS NOISE DOES NOT RESULT IN ANY DAMAGE BUT MAY BE OBJECTIONABLE TO SOME CUSTOMERS.

THIS NOISE SHOULD NOT BE CONFUSED WITH OTHER SOURCES OF NOISE SUCH AS ACCESSORY DRIVE TICKS, EXHAUST SYSTEM RATTLES, CLUTCH OR FLYWHEEL NOISE, ETC.

CAUSE:

THE CAUSE IS A ROCKING MOTION OF THE PISTON IN THE BORE THAT CAN OCCUR, UNDER CERTAIN CONDITIONS.

DIAGNOSIS:

IF POSSIBLE, HAVE THE CUSTOMER LEAVE THE VEHICLE OVERNIGHT TO ALLOW THE ENGINE TO STABILIZE AT AMBIENT TEMPERATURE. START THE VEHICLE AND AS SOON AS POSSIBLE, OPERATE THE ENGINE BETWEEN 2000 AND 2200 RPM. IF NECESSARY, ON AUTOMATIC TRANSMISSION EQUIPPED VEHICLES, SHIFT THE VEHICLE MANUALLY INTO 1ST OR 2ND GEAR TO MAINTAIN THE RPM RANGE.

CAUTION:

IN MANUAL 1ST OR 2ND, THE VEHICLE MAY NOT BE ABLE TO MAINTAIN NORMAL TRAFFIC SPEED WITHIN THE RANGE BETWEEN 2000 AND 2200 RPM. BE AWARE THAT OTHER DRIVERS MAY NOT BE PREPARED FOR A VEHICLE TRAVELING AT A MUCH SLOWER SPEED. IF POSSIBLE, ATTEMPT TO GO TO A RURAL AREA OR TO AN AREA THAT HAS LIGHT TRAFFIC.

THE NOISE MAY BE LOUDER IF THE AMBIENT TEMPERATURE IS COOLER AND WILL BE MUCH LESS NOTICEABLE WITH THE ENGINE AT OPERATING TEMPERATURE.

CORRECTION:

REPLACE ALL OF THE PISTON AND ROD ASSEMBLIES (OR PISTONS, ONLY ON CERTAIN ENGINES) USING PART NUMBERS FROM THE CHART BELOW.

**PISTON REPLACEMENT:** 1) REMOVE THE ENGINE ACCESSORY BRACKET TO EXPOSE THE FRONT OF THE ENGINE BLOCK AND CYLINDER HEAD MATING AREA.

2) INSPECT THE ENGINE TO SEE IF IT HAS A BRIGHT ORANGE OR RED LETTER "A" ON THE FRONT OF THE ENGINE BLOCK BEHIND THE ACCESSORY BRACKET, DIRECTLY ABOVE THE TIMING CHAIN HOUSING COVER AND BELOW THE ENGINE BLOCK TO CYLINDER HEAD MATING AREA. IF SO, THE PISTONS MUST BE REPLACED USING THE APPROPRIATE PART NUMBERS FROM THE TABLE BELOW.

3) DISASSEMBLE THE ENGINE AS NEEDED TO REMOVE THE PISTONS USING THE SERVICE PROCEDURES OUTLINED IN SECTION 6A2 OR THE ENGINE SECTION OF THE APPLICABLE SERVICE MANUAL. NOTICE: MARK THE CONNECTING ROD END CAPS AND THE PISTON RODS TO PREVENT REVERSING THE CAP ON THE ROD. ROD AND CAPS ARE A MACHINED, MATCHED ASSEMBLY. REVERSAL OF THE CAP ON THE ROD MAY CAUSE BINDING OF THE CONNECTING ROD ASSEMBLY TO THE CRANKSHAFT. IF, IN STEP 2 YOU LEARNED THAT THE ENGINE IS AN "A" ENGINE, DISASSEMBLE THE PISTONS FROM THE RODS AND DISCARD THE PISTONS.

4) USING A BALL-TYPE OR SELF-CENTERING HONING TOOL, DEGLAZE THE CYLINDER BORE LIGHTLY, ONLY TO REMOVE ANY DEPOSITS THAT MAY HAVE FORMED. AN EXAMPLE OF THIS TYPE OF HONE WOULD BE A SNAP-ON TOOLS MODEL BCG-89* WITH 180 GRIT STONES MADE OF SILICONE CARBIDE.

5) IF, IN STEP 2 YOU LEARNED THAT THE ENGINE IS AN "A" ENGINE, ASSEMBLE THE PISTONS TO THE CONNECTING RODS USING TOOL J 24086-C.

IMPORTANT: IT IS NECESSARY TO PROPERLY ORIENT THE PISTONS ON THE CONNECTING ROD AND TO ORIENT THE PISTON ROD ASSEMBLY PROPERLY IN THE ENGINE TO PREVENT NOISE. INSPECT THE LOWER END OF THE CONNECTING ROD FOR A "BUMP" ON ONE SIDE THAT POINTS TOWARD THE SMALL END OF THE CONNECTING ROD. THIS "BUMP" IS LOCATED AT THE TOP OF THE THRUST FACE OF THE CONNECTING ROD WHERE THE BEAM OF THE CONNECTING ROD FORMS INTO THE LARGE END. WHEN INSTALLING THE PISTON ON THE CONNECTING ROD, THIS "BUMP" SHOULD FACE AWAY FROM THE ARROW ON THE PISTON CROWN. WITH THE PISTON AND CONNECTING ROD ASSEMBLY PROPERLY IN THE ENGINE, THIS "BUMP" WILL FACE THE REAR OF THE ENGINE AND THE ARROW ON THE PISTON CROWN WILL FACE THE FRONT OF THE ENGINE.

NOTICE: IF, IN STEP 2 YOU LEARNED THAT THE ENGINE IS AN "A" ENGINE, TO ASSEMBLE THE PISTONS TO THE RODS, IT IS NECESSARY TO USE TOOL J 24086-C OR A FIXTURE THAT DOES NOT PUT PRESSURE AGAINST THE PISTON. ALL PRESS LOAD MUST BE SUPPORTED BY THE CONNECTING ROD. ANY LOAD ON THE PISTON OR PISTON SKIRT WILL DISTORT THE PISTON.

6) INSPECT THE PISTON ROD BEARINGS FOR WEAR USING SERVICE PROCEDURES OUTLINED IN SECTION 6A2B OR THE ENGINE SECTION OF THE APPROPRIATE SERVICE MANUAL. REPLACE BEARINGS WITH THE CORRECT SIZE AS INDICATED BY THE MEASUREMENTS TAKEN. THREE SIZES ARE AVAILABLE FROM GMSPO.

7) INSTALL A NEW CYLINDER HEAD GASKET USING THE PROCEDURE OUTLINED IN SECTION 6A2 IN THE SERVICE MANUAL. IMPORTANT: CYLINDER HEAD FLATNESS SPECIFICATION: THE CYLINDER HEAD CAN BE REUSED IF THE CYLINDER HEAD WARPAGE IS LESS THAN 0.05 MM (0.002 IN.) WITHIN ANY 152 MM (6.0 IN.) AREA OF THE CYLINDER HEAD SEALING SURFACE OR 0.1 MM (0.004 IN.) OVER THE ENTIRE LENGTH OF THE CYLINDER HEAD.

RESURFACE THE CYLINDER HEAD IF WARPAGE IS OVER 0.05 MM (0.002 IN.) WITHIN ANY 152 MM (6.0 IN.) AREA, OR MORE THAN 0.1 MM (0.004 IN.) AND LESS THAN 0.025 MM (0.010 IN.) OVER THE ENTIRE LENGTH OF THE CYLINDER HEAD.

**THE CYLINDER HEAD MUST BE REPLACED IF WARPAGE IS OVER 0.025 MM (0.010 IN.)** NOTICE: NEVER USE ABRASIVE PADS TO CLEAN THE CYLINDER HEAD OR BLOCK SURFACES. AN ABRASIVE PAD MAY DAMAGE THE CYLINDER HEAD AND THE BLOCK. ABRASIVE PADS WILL PRODUCE A FINE GRIT THAT THE OIL FILTER WILL NOT BE ABLE TO REMOVE FROM THE OIL. THIS GRIT IS ABRASIVE AND HAS BEEN KNOWN TO CAUSE INTERNAL ENGINE DAMAGE. ALSO, ABRASIVE PADS MAY ROUND THE CYLINDER HEAD EDGES OR REMOVE ENOUGH METAL DURING CLEANING TO AFFECT CYLINDER HEAD FLATNESS, BOTH OF WHICH ARE KNOWN TO AFFECT THE CYLINDER HEAD GASKET SEAL.

8) SCRUB THE CYLINDER BORE AND REPLACEMENT PISTONS WITH SOAP AND WATER AND REMOVE ANY FOREIGN MATERIAL. THOROUGHLY DRY THE PARTS, INSTALL NEW PISTON RINGS, GM P/N 10159570 AND COAT THE CYLINDER BORE, PISTON SKIRT, AND PISTON RINGS, WITH ENGINE OIL.

9) INSTALL ALL FOUR (4) PISTONS OR PISTON AND ROD ASSEMBLIES USING SERVICE PROCEDURES OUTLINED IN SECTION 6A2B OR THE ENGINE SECTION OF THE APPROPRIATE SERVICE MANUAL.

IT IS NOT NECESSARY OR RECOMMENDED TO MEASURE THE PISTON TO BORE CLEARANCE WHEN INSTALLING THESE PISTON AND CONNECTING ROD ASSEMBLIES.

IMPORTANT: ALL FOUR PISTONS MUST BE REPLACED.

ALL 1996 CHEVROLET CAVALIER AND PONTIAC SUNFIRE MODELS REQUIRE USE OF THE FOLLOWING REVISION OF THE ENGINE COOLANT SERVICE FILL PROCEDURE FOR PAGE 6B-8 OF THE 1996 J CAR SERVICE MANUAL (FOUND IN SERVICE BULLETIN 63-62-03).

IMPORTANT: THE USE OF MECHANICAL FILL EQUIPMENT IS NOT RECOMMENDED.

**ENGINE COOLANT SERVICE FILL PROCEDURE (WITHOUT ENGINE VENT LINE)** 1. CLOSE THE RADIATOR DRAIN VALVE AND REMOVE DRAIN TUBE. 2. INSTALL ALL ENGINE BLOCK DRAIN PLUGS IF PREVIOUSLY REMOVED. USE PIPE SEALER WHEN INSTALLING DRAIN PLUGS. 3. WHEN ADDING ENGINE COOLANT, IT IS IMPORTANT THAT GM GOODWRENCH DEX-COOL(R) (ORANGE-COLORED, SILICATE-FREE) COOLANT MEETING GM SPECIFICATION 6277M BE USED. IF SILICATE-CONTAINING COOLANT IS ADDED TO THE SYSTEM, PREMATURE ENGINE, HEATER CORE, OR RADIATOR CORROSION MAY RESULT. IN ADDITION, THE ENGINE COOLANT WILL REQUIRE CHANGE SOONER AT 50,000 KM (30,000 MILES) OR 24 MONTHS. 4. OPEN BOTH BLEEDER VALVES. ONE IS ON THE HEATER RETURN PIPE AND ONE IS ON THE WATER OUTLET (BEHIND AIR INTAKE PLENUM). 5. FILL THE COOLING SYSTEM THROUGH THE SURGE TANK UNTIL COOLANT IS EXPELLED OUT BOTH BLEEDER VALVES. 6. CLOSE BLEEDER VALVES. 7. TOP OFF COOLANT LEVEL IN SURGE TANK TO A LEVEL EVEN WITH THE FLAT HORIZONTAL WALL BELOW THE VENT LINES. IMPORTANT: LEAVE SURGE TANK CAP OFF. 8. START ENGINE. 9. OPEN WATER OUTLET BLEEDER VALVE AND LEAVE VALVE OPEN UNTIL A SOLID STREAM OF COOLANT IS EXPELLED, THEN CLOSE VALVE. REPEAT THIS EVERY 3 MINUTES UNTIL THE THERMOSTAT OPENS. IMPORTANT: THERMOSTAT IS CONSIDERED OPEN WHEN UPPER RADIATOR HOSE IS HOT AT RADIATOR CONNECTION. IMPORTANT: TURN HVAC CONTROLS TO "HEATER," FULL HOT AND CHECK FOR WARM AIR DURING THE FIRST FIVE MINUTES AFTER ENGINE START. IF NO HOT AIR IS PRESENT, START PROCEDURE AGAIN AT STEP 4. 10. TOP OFF ENGINE COOLANT, IF NECESSARY, TO THE SAME LEVEL AS IN STEP SEVEN (7). 11. INSTALL SURGE TANK CAP.

**ENGINE COOLANT SERVICE FILL PROCEDURE (WITH ENGINE VENT LINE)** 1. CLOSE THE RADIATOR DRAIN VALVE AND REMOVE DRAIN TUBE. 2. INSTALL ALL ENGINE BLOCK DRAIN PLUGS IF PREVIOUSLY REMOVED. USE PIPE SEALER WHEN INSTALLING DRAIN PLUGS. WHEN ADDING ENGINE COOLANT, IT IS IMPORTANT THAT GM GOODWRENCH DEX-COOL(R) (ORANGE- COLORED, SILICATE-FREE) COOLANT MEETING GM SPECIFICATION 6277M BE USED. IF SILICATE-CONTAINING COOLANT IS ADDED TO THE SYSTEM, PREMATURE ENGINE, HEATER CORE, OR RADIATOR CORROSION MAY RESULT. IN ADDITION, THE ENGINE COOLANT WILL REQUIRE CHANGE SOONER, AT 50,000 KM (30,000 MILES) OR 24 MONTHS. 3. OPEN THE BLEEDER VALVE ON THE HEATER RETURN PIPE. 4. FILL THE COOLING SYSTEM THROUGH THE SURGE TANK UNTIL COOLANT IS EXPELLED OUT THE HEATER RETURN PIPE BLEEDER VALVE. 5. CLOSE BLEEDER VALVE. 6. TOP OFF COOLANT LEVEL IN SURGE TANK TO A LEVEL EVEN WITH THE FLAT HORIZONTAL WALL BELOW THE VENT LINES (APPROXIMATELY 1" BELOW FILL NECK). IMPORTANT: LEAVE SURGE TANK CAP OFF. 7. START AND RUN ENGINE UNTIL THERMOSTAT OPENS. IMPORTANT: THERMOSTAT IS CONSIDERED OPEN WHEN UPPER RADIATOR HOSE IS HOT AT RADIATOR CONNECTION. IMPORTANT: TURN HVAC CONTROLS TO "HEATER," FULL HOT AND CHECK FOR WARM AIR DURING THE FIRST FIVE (5) MINUTES AFTER ENGINE START. IF NO HOT AIR IS PRESENT, START PROCEDURE AGAIN AT STEP THREE (3). 8. TOP OFF ENGINE COOLANT, IF NECESSARY, TO THE SAME LEVEL AS IN STEP SIX (6). 9. INSTALL SURGE TANK CAP.

THE "SNAP-ON TOOLS MODEL BCG 89" CAN BE OBTAINED BY CONTACTING A LOCAL SNAP-ON TOOLS REPRESENTATIVE.

*WE BELIEVE THIS SOURCE AND THEIR PRODUCTS TO BE RELIABLE. THERE MAY BE ADDITIONAL MANUFACTURERS OF SUCH PRODUCTS. GENERAL MOTORS DOES NOT ENDORSE, INDICATE ANY PREFERENCE FOR, OR ASSUME ANY RESPONSIBILITY FOR THE PRODUCTS FROM THIS FIRM OR FOR ANY SUCH ITEMS WHICH MAY BE AVAILABLE FROM OTHER SOURCES.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

VEHICLE PROCEDURE LABOR OPERATION LABOR HOURS S-TRUCK PISTON, REPLACE J1308 9.1* S-TRUCK ADD TO REPLACE ALL PISTONS 2.7 S-TRUCK ADD TO ASSEMBLE FOUR PISTONS TO RODS 1.4

A-CAR PISTON, REPLACE J1308 7.1** A-CAR ADD TO REPLACE ALL PISTONS 2.0 A-CAR ADD TO ASSEMBLE FOUR PISTONS TO RODS 1.1

J-CAR PISTON, REPLACE J1308 7.2** J-CAR ADD TO REPLACE ALL PISTONS 2.0 J-CAR ADD TO ASSEMBLE FOUR PISTONS TO RODS 1.1

L-CAR PISTON, REPLACE J1308 6.8** L-CAR ADD TO REPLACE ALL PISTONS 2.0 L-CAR ADD TO ASSEMBLE FOUR PISTONS TO RODS 1.1

*FOR VEHICLES WITH AIR CONDITIONING, ADD 0.9 HOURS. TO CLEAN PARTS ON VEHICLES WITH MORE THAN 30,000 MILES (48,000 KM) ADD 0.3 HOURS.

**FOR VEHICLES WITH AIR CONDITIONING, ADD 0.3 HOURS. TO CLEAN PARTS ON VEHICLES WITH MORE THAN 30,000 MILES (48,000 KM) ADD 0.3 HOURS.

PARTS INFORMATION:

DESCRIPTION QUANTITY GM PART NUMBER FOR ENGINES NOT MARKED "A" PISTON AND CONNECTING ROD ASSY. KIT (INCLUDES 4 PISTONS) 1 24576793

PISTON WITH PIN FOR ENGINES MARKED "A" 4 24576692

HEAD GASKET J, A & L CAR. 1 24576546

HEAD GASKET S TRUCK 1 24576547

EXH. MAN. TO EXH. PIPE GASKET J CAR 1997 1 24575494

EXH. MAN. TO EXH. PIPE GASKET A,J AND L CAR 1994-96 1 24575412

EXH. MAN. TO EXH. PIPE GASKET S TRUCK 1996 & 1997 1 15740141

EXH. MAN. TO EXH. PIPE GASKET S TRUCK 1994 & 1995 1 15547998

REAR OIL PAN SEAL 1 14076392

VALVE COVER GASKET 1 24575855

PISTON RING SET FOR 4 10159570 1 PISTON

FIGURES: 0 ATTACHMENTS: 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.