Muffler - Thumping Noise in Park or Drive
File In Section: 6 - EngineBulletin No.: 83-66-01
Date: March, 1998
Subject:
Thumping Noise from the Muffler Can Be Heard at Idle in Park or Drive (Replace Muffler)
Models:
1995-98 Chevrolet Cavalier
1995-98 Pontiac Sunfire
with 2.2L Engine (VIN 4 - RPO LN2)
Condition
Some owners may comment that a thumping or oil canning noise may be heard on cold or hot exhaust systems. This noise can be heard while at idle in park or drive.
Cause
Condition may be caused by noise produced by the outer and inner muffler shells separating from different thermal expansion rates. The outer shell usually will buckle in the rear chamber of the muffler. Pressure pulsation from the engine causes the outer shell to resonate and produce the thumping noise.
Important:
Mufflers built after October, 1997 have an additional twelve spot welds added to prevent this condition.
Correction
Replace the muffler with P/N 22614984 (Chevrolet) and P/N 22614985 (Pontiac).
Parts Information
P/N Description
22614984 (Chevrolet) Muffler Assembly
22614985 (Pontiac)
Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation Description Labor Time
L2584 Muffler - Replace Use published
labor operation
time