NOISE/GROWL FROM MUFFLER (REPLACE MUFFLER)

Subject: NOISE/GROWL FROM MUFFLER

Model and Year: 1992 S/T 4-DOOR TRUCKS WITH 4.3L TBI ENGINE

Some owners of 1992 S/T four door utility vehicles with a 4.3L TBI engine (VIN code Z) built between the VIN breakpoints listed below may experience loud or noisy mufflers. This is due to the muffler's tuning tube being built out of manufacturers specifications. To correct this condition, replacement of the muffler is required.

VEHICLES INVOLVED:

VIN

From SOP 1992 to N2113412

SERVICE PROCEDURE:

Removing Exhaust Parts

CAUTION:

Always wear protective goggles and gloves when removing exhaust parts as falling 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 S/T Service Manual section 6F Exhaust System for additional information.

SERVICE PARTS INFORMATION

Part Number Description ----------- ----------- 15662525 Muffler 15662531 Pipe Assembly 15595048 Clamp

Parts are currently available from GMSPO.

WARRANTY INFORMATION

For vehicles repaired under warranty use:

Labor Operation: L2584

Use applicable labor time guide for labor hours.

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.