C 30 1 Ton Pickup 2WD V8-454 7.4L VIN W 4-bbl (1983)
Exhaust Manifold: Customer Interest
Engine - Noise, Updated Exhaust Manifolds
File In Section: 6 - Engine
Bulletin 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.
