Engine - Noise, Updated Exhaust Manifolds
File In Section: 6 - EngineBulletin No.: 37-66-02B
Date: November, 1996
Subject:
Engine Noise (Replace with New Design Cast Iron Exhaust Manifold and Stainless Steel Gasket)
Models:
1982-95 Chevrolet and GMC C/K, R/V, G, P Models with 7.4L Engine (VIN N - RPO L19) and Cast Iron Exhaust Manifolds
This bulletin is being revised to update the correction information statement and additional service parts information listed under all models. Please discard Corporate Bulletin Number 37-66-02A (Section 6 - Engine).
Important:
This bulletin does not apply to engines with stainless steel exhaust manifolds (Option H5D).
Condition
Some owners may comment on an engine noise. The noise is normally loudest when the engine is cold.
Cause
An exhaust leak may have developed between the cast iron exhaust manifold and the cylinder head mating surface. The cast iron exhaust manifold has warped at the ends.
Correction
A new exhaust manifold, stainless steel gasket and attaching hardware has been developed to correct this condition. Replace the existing cast iron exhaust manifold and gasket with the new design exhaust manifold, stainless steel gasket and new attaching hardware. Discard the existing hardware since it will not be reused.
Parts are currently available from GMSPO.
Warranty Information
Labor Operation Description Labor Time
J0100 Manifold, Exhaust Use published labor
RH - Replace operation time
J0101 Manifold, Exhaust Use published labor operation
LH - Replace time
Trouble Code 92.