Cylinder Head - New Bolt Tightening Procedure
Bulletin: 86-6-4Date: Nov.. '85
Ref. No.: 86-010-6
SUBJECT: NEW CYLINDER HEAD BOLT TIGHTENING PROCEDURE
MODELS AFFECTED: 1986 SKYLARK, SOMERSET & CENTURYS EQUIPPED WITH 2.5L ENGINES (VIN CODES R & U)
A new bolt tightening procedure has been developed for the above engines 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 installation.
All residual oil should be wiped from the cylinder head mating surfaces.
^ Apply sealing compound, Part #1052080 to threads of bolts #9 and #10.
^ Install all cylinder head bolts and torque to 25 N-m (9 ft.lbs.) in specified sequence (See Illustration).
^ Repeat the sequence bringing torque to 30 N-m (22 ft.lbs.) on all bolts except #9. Torque #9 to 40 N-m. (29 ft.lbs.)
^ Repeating the sequence, rotate all bolts except #9, 120 degrees (two flats).
^ #9 bolt should be rotated 90 degrees, 1/4 turn.