Exhaust - Metallic Noise or Rap Heard on Cold Exhaust
File In Section: 6 - EngineBulletin No.: 63-66-04C
Date: September, 1998
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)
This bulletin is being revised to change labor time information. Please discard Corporate Bulletin Number 63-66-04B (Section 6 - Engine).
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°F (204°C) 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 Labor Time
L2720 0.4 hr