Engine - Oil Consumption/Rough Idle/Spark Plug Fouling
File In Section: 6 - EngineBulletin No.: 57-61-15A
Date: November, 1996
Subject:
Excessive Oil Consumption, Miss, Rough Idle or Spark Plug Fouling
(Cylinder Head Assembly Exchange Program)
Models:
1995 Chevrolet and GMC, C/K, G, P Models with 7.4L Engine (VIN N - RPO L19)
This bulletin is being revised to add a note and provide new information in the correction section of this bulletin. Please discard Corporate Bulletin Number 57-61-15.
These VIN ranges are known to be possible for oil consumption, however, a few vehicles with VINs outside the given ranges may be affected.
Important:
The exchange procedure described in Corporate Bulletin 57-61-15 is no longer in effect. If a replacement cylinder head is necessary, refer to the correction statement in this bulletin.
Condition
Some owners may comment on excessive oil consumption, engine miss or rough idle. Vehicles affected may exhibit spark plug fouling on only one bank of cylinders or only one or two individual spark plugs.
Cause
The affected cylinder head may have been mis-machined which allows oil to be drawn into the engine by intake manifold vacuum where the intake valve guide is pressed into the cylinder head.
Correction
Replace the existing cylinder head assembly with a new cylinder head. The cylinder head assembly is available through GMSPO. Whenever a new cylinder head assembly is ordered, the valves, springs, caps and keepers must be installed into the new cylinder head casting. A new cylinder head gasket and intake gasket should be installed.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation Description Labor Time
J0510 Right Bank Use published labor operation time.
J0511 Left Bank Use published labor operation time.
J0517 Both Banks Use published Labor operation time.