BOLT TIGHTENING PROCEDURE CYLINDER HEAD BOLTS

MODELS: 1985 AND 1986 S/T AND M MODEL

A new bolt tightening procedure has been developed for the 2.5L engine which improves head to block clamping force and assures more uniform tightening. The procedure to be used is as follows:

- Cylinder head bolts should be washed in solvent and dry at the time of installation. All residual oil should be wiped from the cylinder head mating surfaces.

- Apply sealing compound, P/N 1052080, to threads of bolts No. 9 and No. 10 (See Figure No.1).

- Apply a light coat of engine oil to the threads and underside of the bolt heads of bolts No. 1 through No. 8.

- Install all cylinder head bolts and torque to 25 N.m (18 ft. lbs.) in specified sequence (See Figure No. 1).

- Repeat the sequence, bringing torque to 30 N.m (22 ft. lbs.) on all bolts except No. 9. Torque No. 9 to 40 N.m (29 ft. lbs.)

- Draw a line across the head of each bolt with a marking crayon to mark the position of each bolt (See Figure No. 2).

- Repeat the sequence, rotate all bolts except No 9, 120 degrees (two flats) (See Figure No. 2).

- No. 9 bolt should be rotated 90 degrees, 1/4 turn.

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.