Camshaft Thrust Plate - New Design

87buick14

Bulletin: 87-6-21A

Date: Dec., '87

Ref.No. 87-142A-6

Corp. Ref. No. 706007R
SUBJECT: NEW DESIGN SPRING AND BEARING ASSEMBLY (CAMSHAFT THRUST)


MODELS AFFECTED: ALL 3.0L 1982-85 LK9 (VIN CODE E), 1985-87 LN7 (VIN CODE L), AND, 3.8L 1984-85 LN3 (VIN CODE 3), 1986 LG2 (VIN CODE B), 1986-87 LG3 (VIN CODE 3) V-6 ENGINES



NOTICE: This bulletin corrects the Models Affected listing, changes the design illustration, and replaces dealer service bulletin 87-6-21, which should be discarded


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 in conjunction 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.