For 1990-2009 cars

# TIMING CHAIN WEAR PROCEDURE FOR CHECKING

#### VEHICLES AFFECTED: 1982-85 D, 1985-1988 C, 1982-88 E/K, 1987-88 V,4.1L AND 4.5L V-8 ENGINES

As engines reach higher mileages, technicians may question the degree of wear on the camshaft timing chain to decide if replacement is required. The following guidelines should be observed.

With the timing chain and gears assembled on the engine as shown in Figure, load (rotate) the camshaft so that all of the slack is on one side of the timing chain. With this condition maintained, measure the total side-to-side movement of the timing chain on the slack side at a point midway between the gears. Total chain movement should not exceed 12mm (0.50").

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.