1997 - 1998 Corvette: Service Bulletin: Exhaust Muffler Insulator Rumble Noise

Subject: EXHAUST MUFFLER INSULATOR RUMBLE NOISE (INSTALL NEW MUFFLER INSULATORS)
Source: Chevrolet Dealer Technical Service Bulletin
Number: 83-66-07 - (07/17/1998)
Models: 1997-98 CHEVROLET CORVETTE - BUILT PRIOR TO VIN BREAKPOINT W5127417

Condition:

SSOME OWNERS MAY COMMENT ABOUT A LOW FREQUENCY RUMBLE/NON-METALLIC RATTLE TYPE NOISE THAT IS AUDIBLE IN THE PASSENGER COMPARTMENT AND APPEARS TO BE COMING FROM THE REAR OF THE VEHICLE. THIS CONDITION IS MOST APPARENT WHEN THE VEHICLE IS BEING OPERATED AT LOW SPEEDS OF 5-25 MPH (8-40 KM/H) OVER A ROUGH ROAD SURFACE.

Cause:

THIS NOISE MAY BE GENERATED BY THE VERTICAL MOVEMENT OF THE BLADE OF THE MUFFLER HANGER IN THE OPENING OF THE EXHAUST MUFFLER INSULATOR.

Correction:

REPLACE THE RIGHT AND LEFT SIDE REAR MUFFLER INSULATORS WITH THE NEW DESIGN INSULATORS (P/N 10421196), FOLLOWING THE PROCEDURE BELOW:

1. REMOVE NUTS (TWO PER SIDE/INSULATOR) SECURING INSULATORS TO THE UNDERBODY.

2. REMOVE EXISTING INSULATORS AND DISCARD.

3. INSTALL NEW INSULATORS (P/N 10421196) ONTO THE BLADES OF THE MUFFLER HANGERS, UTILIZING SOAPY WATER AS A LUBRICANT TO AID ASSEMBLY, IF REQUIRED.

4. POSITION INSULATORS ON UNDERBODY STUDS. INSTALL NUTS AND TORQUE TO 16 N.M (12 LB FT).

Parts Information:

P/N DESCRIPTION
========= ======================
10421196 INSULATOR, EXHAUST MUFFLER

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these 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 your GM dealer for information on whether your vehicle may benefit from the information.