BOLT TIGHTENING PROCEDURE CYLINDER HEAD BOLTS

VEHICLES AFFECTED: 1985 and 1986 'A', 'F', 'N', P', and 'X' Cars, S/T Trucks and 'M'-Vans

THIS SUPERSEDES ALL PREVIOUS 1986 PUBLICATIONS DEALING WITH TIGHTENING 2.5L CYLINDER HEAD BOLTS.

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:

1. Cylinder head bolts should be washed in solvent and dried prior to installation. All residual oil should be wiped from the cylinder head mating surface.

2. Apply a light coat of engine oll to the threads and the underside of the bolt head of bolts No. 1 thru No. 8.

3. Apply sealing compound P/N 992545 to threads of bolts No. 9 and No. 10.

4. Install all cylinder head bolts and torque to 25 N.m (18 lb. ft.) in specified sequence (see illustration).

5. Repeat the sequence bringing torque to 30 N.m (22 lb. ft.) on all bolts except No. 9. Torque No. 9 to 40 N.m (30 lb. ft.).

6. Repeating the sequence, rotate all bolts except No. 9, 120 degrees (two (2) flats).

7. No. 9 bolt should be rotated 90 degrees (1/4 turn).

Use applicable labour time and operation number for cylinder head gasket replacement.

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.