Torque Specifications
Bulletin 86-6-4ADate Feb. '86
Ref. No. 86-010A-6
SUBJECT: NEW CYLINDER HEAD BOLT TIGHTENING PROCEDURE FOR 2.5L CYLINDER HEAD
MODELS AFFECTED: 1986 SKYLARK, SOMERSET AND CENTURYS EQUIPPED WITH 2.5L ENGINES (VIN Codes "R & U")
THIS BULLETIN 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 oil to the threads and the underside of the bolt head of bolts # 1 thru # 8.
3. Apply sealing compound, Part Number 1052080, to threads of bolts # 9 and # 10.
BOLT POSITIONS AND BOLT TIGHTENING SEQUENCE:
4. Install all cylinder head bolts and torque to 25 Nm (18 ft.lbs.) in specified sequence (see illustration).
5. Repeat the sequence bringing torque to 30 Nm (22 ft.lbs.) on all bolts except # 9. Torque # 9 to 40 Nm (30 ft.lbs.).
6. Repeating the sequence, rotate all bolts, except # 9, 120 degrees (two [2] flats).
7. # 9 bolt should be rotated 90 degrees (1/4 turn).