INFO. METALLIC NOISE OR COLD RAP HEARD ON COLD EXHAUST. Chevrolet Cavalier 1996

REVISION: 04/02/98 DIVS INVL 1 2 7

THIS BULLETIN IS BEING REVISED TO CHANGE IT FROM INFORMATIONAL TO TECHNICAL, ADD THE 1998 MODEL YEAR, PARTS INFORMATION AND ARTWORK. PLEASE DISCARD CORPORATE BULLETIN NUMBER 63-66-04 (SECTION 6 - ENGINE) ______________________________________________________________________

REVISION: 06/11/98 DIVS INVL 1 2 7

THIS BULLETIN IS BEING REVISED TO ADD AN ADDITIONAL PART NUMBER AND UPDATE THE CORRECTION PROCEDURE. PLEASE DISCARD CORPORATE BULLETIN NUMBER 63-66-04A (SECTION 6 - ENGINE). ______________________________________________________________________

REVISION: 08/31/98 DIVS INVL 1 2 7

THIS BULLETIN IS BEING REVISED TO CHANGE LABOR TIME INFORMATION. PLEASE DISCARD CORPORATE BULLETIN NUMBER 63-66-04B (SECTION 6 - ENGINE). ______________________________________________________________________

SUBJECT: METALLIC NOISE OR "COLD RAP" HEARD ON COLD EXHAUST SYSTEMS DURING FREE REV OR ENGINE LOAD (INSTALL RESONATOR ASSEMBLY)

MODELS: 1995-98 CHEVROLET CAVALIER 1995-98 PONTIAC SUNFIRE WITH 2.2L ENGINE (VIN 4 - RPO LN2)

CONDITION:

SOME OWNERS MAY COMMENT THAT A METALLIC NOISE OR "COLD RAP" MAY BE HEARD ON COLD EXHAUST SYSTEMS. CONDITION OCCURS PRIOR TO MUFFLER INLET GASSES EXCEEDING 400 DEGREES FAHRENHEIT (204 DEGREES CELSIUS) AND IS FOUND AT 2800 RPMS DURING FREE REV OR ENGINE LOAD.

CAUSE:

THE RESONATOR FREQUENCIES, IN COMBINATION WITH AMBIENT CONDITIONS AND EXHAUST TUNING, MAY CREATE THE "COLD RAP" CONDITION.

CORRECTION:

A RESONATOR ASSEMBLY (FIGURE 1) IS AVAILABLE TO CORRECT THIS CONDITION.

INSTALL RESONATOR ASSEMBLY (P/N 22610121) TO CURRENT EXHAUST PIPE JUST BEHIND THE CATALYTIC CONVERTER.

ATTACH BY CUTTING EXHAUST PIPE 381 MM (15 IN) BEHIND FRONT EXHAUST PIPE FLANGE. SLIP EXPANDED PIPE OF ASSEMBLY OVER EXISTING PIPE. REPLACE GASKET (P/N 22545048). ATTACH RESONATOR ASSEMBLY TO FLANGE OF CONVERTER WITH THREE BOLTS. TORQUE BOLTS TO 30 N.M (22 LB FT). ATTACH PIPE WITH U-CLAMP. ALIGN RESONATOR ASSEMBLY IN TUNNEL AREA. VERIFY 20 MM (0.8 IN) CLEARANCE TO HEAT SHIELD. TIGHTEN U-CLAMP TO 30 N.M (22 LB FT).

PARTS INFORMATION:

P/N DESCRIPTION ==================== =============================

22610121 RESONATOR ASSEMBLY

22545048 GASKET

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OPERATION NUMBER: L2720 LABOR OPERATION TIME: 0.4 HR

FIGURES: 01 ATTACHMENTS: 00

Object Number: 336464 Size: FS

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.