TAIL PIPE SMOKE ON START-UP (INSTALL NEW VALVE SEAL KIT)

SUBJECT: TAILPIPE SMOKE ON STARTUP (INSTALL NEW VALVE STEM SEAL KIT)

MODELS: 1987-91 C/K AND R/V/G/P MODELS WITH 5.0L AND 5.7L ENGINES

THIS BULLETIN CANCELS AND SUPERSEDES GMC TRUCK BULLETIN 89-6A-109, OCTOBER 1989 (CORPORATE BULLETIN #836546R) AND GMC TRUCK BULLETIN 90-6A-80, JULY 1990 (CORPORATE BULLETIN #066102). ALL COPIES OF THE ABOVE BULLETINS SHOULD BE DISCARDED.

Some owners of the above vehicles may comment on a puff of blue or bluish white tailpipe smoke on startup. This may be caused by oil leaking past valve stem seals and being deposited on exhaust valve(s).

A new valve stem seal kit (P/N 12511890) has been released to address this concern. The kit incorporates a new umbrella seal with a "viton" insert for the exhaust valve stem.

Parts are currently available from GMSPO. Use applicable labor operations and times.

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.