SEVERE RATTLE NOISE, NO THROTTLE RESPONSE ON START-UP. GMC Truck GMC C Pickup

SUBJECT: SEVERE RATTLE NOISE AND NO THROTTLE RESPONSE ON START-UP (REPLACE FLYWHEEL)

MODELS: 1992-94 CHEVROLET AND GMC TRUCK C/K 2,3 MODELS EQUIPPED WITH 6.5L TURBO-DIESEL (VIN CODE F - RPO L65) AND 5 SPEED MANUAL TRANSMISSION (RPO MT8)

CONDITION:

SOME OWNERS MAY EXPERIENCE A SEVERE RATTLE NOISE ALONG WITH REDUCED IDLE SPEED AND NO THROTTLE RESPONSE WHILE STARTING THEIR VEHICLE. THIS NOISE HAS BEEN DESCRIBED IN SOME CASES AS SOUNDING LIKE A MACHINE GUN. THESE CONDITIONS ARE MORE LIKELY TO OCCUR ON A HOT RESTART WITH THE A/C ENGAGED. THE LACK OF THROTTLE RESPONSE MAY LAST FIVE OR MORE SECONDS BUT ALWAYS ACCOMPANIES THIS CONDITION.

IMPORTANT: THIS CONDITION SHOULD NOT BE CONFUSED WITH THE NORMAL NOISE HEARD AS THE ENGINE IS STARTED UP OR TURNED OFF. THIS NOISE LASTS FROM 1 TO 2 SECONDS, AND WILL NOT INTERFERE WITH THROTTLE RESPONSE.

CAUSE:

THE DUAL MASS FLYWHEEL (DMF) GOES INTO A RESONANCE CONDITION AND THE DAMPER IS UNABLE TO PROVIDE PROPER DAMPING.

CORRECTION:

REPLACE THE DMF WITH THE PART NUMBER LISTED BELOW.

IMPORTANT: THESE REVISED PARTS WERE INSTALLED IN PRODUCTION APPROXIMATELY FEBRUARY 1, 1994. THE REVISED PARTS ARE IDENTIFIED BY THE LETTER M STAMPED ON THE ENGINE SIDE OF THE FLYWHEEL NEAR THE OUTER ROW OF RIVETS. THIS LETTER M IS ALSO COVERED WITH A DOT OF WHITE PAINT.

SERVICE PROCEDURE:

REPLACE THE DMF FOLLOWING PROCEDURES AS OUTLINED IN THE APPROPRIATE C/K SERVICE MANUAL, SECTION 6A6 - FLYWHEEL REPLACEMENT.

SERVICE PARTS INFORMATION:

P/N DESCRIPTION QTY 15986799 FLYWHEEL ASM, (L65) 1

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OP DESCRIPTION LABOR TIME J1420 FLYWHEEL, REPLACE USE PUBLISHED LABOR OPERATION TIME

FIGURES: 0

CAPTIONS:

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.