VALVE TRAIN NOISE INSTALL REVISED VALVE SPRINGS

VEHICLES AFFECTED: 87-88 V, 88-89 C/E/K WITH 4.1L AND 4.5L ENGINES

* This bulletin cancels and replaces Bulletin 89-641-100 and 89-645-101.

Some 1988-1989 DeVilles, Fleetwoods, Eldorados, and Sevilles and 1987-1988 Allantes may experience a valve train speed noise most often described as "lifter noise" or "lifter tick". Typically this noise is loudest when the engine is started cold and gets quieter as the engine reaches operating temperature but never quite disappears. It is most noticeable at idle, particularly when a nearby object reflects the noise.

To repair this condition on 1987-1988 Allantes and 1988-1989 DeVilles, Fleetwoods, Eldorados, and Sevilles, install a set of revised rate valve springs, P/N 1649686 (16 required). These third design springs are used in 1990 DeVille, Fleetwood, Eldorado, and Seville production engines. NOTE: The 1989-1990 high output Allante engine uses a unique valve spring.

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.