MUFFLER TONE QUALITY (DIAG./ INSTALL RETURNED MUFFLER)

SUBJECT: L35 MUFFLER TONE QUALITY (DIAGNOSE/INSTALL RETUNED MUFFLER)

VEHICLES AFFECTED: 1992 "S/T" UTILITY TRUCKS WITH 4.3L ENGINE (VIN W, RPO L35)

Owners of some 1992 S/T Utility vehicles with 4.3L CPI engines (VIN W, RPO L35) built before the VIN breakpoints listed below may comment on louder than normal exhaust noise. A retuned muffler is currently available which will reduce the amount of audible noise.

VEHICLES INVOLVED:

Pontiac West Assembly Plant:

Make Built Before VIN ---- ---------------- GMC 1GTCS14R9N0515773

CHEVROLET 1GNCT18W8N0151461

Moraine Assembly Plant:

Make Built Before VIN ---- ---------------- GMC 1GKDT13W8N2531932

CHEVROLET 1GNDT13W4N2204849

OLDSMOBILE 1GHDT13WXN2710107

SERVICE PROCEDURE:

Removing Exhaust Parts

CAUTION:

Always wear protective goggles and gloves when removing exhaust parts as failing rust and sharp edges from worn exhaust components could result in serious personal injury.

Using a penetrating oil on the threads of U-bolts can assist in the removal of the exhaust components.

Installing Exhaust Parts

When installing a new muffler and tailpipe, on any model, check for proper alignment. Rattles and noise vibrations in the exhaust system are usually caused by a misalignment of parts. When aligning the system, leave all bolts or nuts loose until all parts are properly aligned, then tighten, working from the front to rear. Exhaust system hangers, hanger brackets, and clamps which are damaged should be replaced to maintain exhaust system alignment. Refer to X-9229 Sonoma and Jimmy Service Manual section 6F Exhaust System for additional information.

SERVICE PARTS INFORMATION:

Part Number Description ----------- ----------- 12541384 Muffler - 2 Dr. and 4 Dr. Jimmy

15662532 Tailpipe - 2 Dr. Jimmy

15662531 Tailpipe - 4 Dr. Jimmy

15595048 Clamp - 2 Dr. and 4 Dr. Jimmy

WARRANTY INFORMATION:

For vehicles repaired under warranty use:

Labour Operation: L2584

Labour Time: 0.4 hrs.

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.