ENGINE KNOCKING NOISE NEW SPRING & BEARING ASSEMBLY

NEW DESIGN SPRING AND BEARING ASSEMBLY (CAMSHAFT THRUST)

3.0L 1985-87 LN7 (VIN CODE L) AND 1987 LG3 V6 ENGINES (VIN CODE 3)

"This bulletin supersedes butletin 87-6(Gasoline)-68 which should be discarded. This butletin includes a new part number. "

Some of the above engines may experience excessive wear to the front cover thrust surface and the camshaft thrust button. An engine with this condition may exhibit a knocking noise most audible just above idle. This knocking noise could be caused by the camshaft chucking (fore and aft movement) in the block.

A needle bearing and spring assembly, Part Number 25532588, is available through GMSPO to address the above conditions. The needle bearing will reduce wear to the front cover thrust surfaces and the spring has a higher load rating which will reduce camshaft chucking.

NOTICE: A HIGHER LOAD RATE SPRING AND BEARING ASSEMBLY SHOULD NOT BE USED WITH THE EARLY DESIGN PHENOLIC PLASTIC BUTTON. FIRST AND SECOND DESIGNS ARE ILLUSTRATED ON THE REVERSE SIDE.

When servicing these engines with the front cover removed, for any other reason, install the new spring and bearing assembly if wear to the button is noted. The front cover does not need to be replaced unless the thrust surface is out of flatness by more than 1/16 of an inch.

Replacement of the camshaft is not necessary unless other obvious conditions are visibly detected.

Use applicable labor operation number and time for front cover replacement.

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.