ROLLER LIFTER CAMSHAFT (NORMAL APPEARANCE DESCRIBED)

VEHICLES AFFECTED: 1987-88 B/F/Y CARS WITH 4.3L, (VIN CODE Z), 5.0L (VIN CODE E, F, H) AND 5.7L (VIN CODE 8)

The camshafts currently used in roller lifter engines are made of steel and polished to a fine mat finish. After running the engine for a short period of time, the lifter track (the path the lifter contacts) on the cam lobe burnishes to a smooth mirror finish. This results in a shiny path around the cam lobe which varies in width and is surrounded by areas with a dull off color surface finish. This burnishing is a desirable work hardening condition and should not be confused with wear.

As a result of this unusual appearance, any decision to replace a roller lifter style camshaft should be based on measuring lift or on the existence of a wear step greater than .005" on the face of the cam lobe. The decision should not be made based on the appearance of the cam lobe surface.

This is an informational bulletin.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.