Removal Procedure

Important:  The timing chain housing to cylinder block and the camshaft housing gaskets can be replaced without removing the timing chain housing from the vehicle.

Removal of the timing chain housing is only required when additional service is being performed on the timing chain housing.

1. Disconnect the negative battery cable.
2. Remove the engine front cover. Refer to Engine Front Cover Replacement .
3. Raise and support the vehicle.
4. Drain cooling system.

   Important:  The timing chain must be marked prior to removal. If the chain is installed with the wear pattern in the opposite direction, noise and increased wear may occur.

5. Remove the timing chain and tensioner.
6. Remove the coolant pump assembly to the timing chain housing nuts.
7. Remove the timing chain housing to the block fasteners (2, 3).
Fig 1: Timing Chain Housing-To-Block Fasteners
Courtesy of GENERAL MOTORS CORP.
8. Remove strut mount bracket. Refer to Engine Mount Strut Bracket Replacement .
9. Remove the four oil pan to front cover bolts.
10. Remove the lowest front cover retaining stud from the timing chain housing. This stud will catch on the body if it is not removed.
11. Lower the vehicle.
12. Remove the camshaft sprocket retaining bolts and the washers while holding the sprockets with the J 39579  .
13. Remove the camshaft sprockets. The camshaft sprockets are identical and interchangeable.
    Fig 2: Camshaft Sprockets

    Courtesy of GENERAL MOTORS CORP.
14. Remove the chain housing to the camshaft housing bolts (1).
15. Remove the timing chain housing and the gaskets. It may be necessary to raise the engine slightly using the J 28467-360. 
16. Inspect the oil pan gasket silicone bead for the following conditions:
    • Cuts or nicks
    • Deformation
    • Separation from the aluminum carrier
17. If any of the conditions exist, replace the pan gasket.

    Important:  Use only enough sealant to restore the silicone bead to its original dimension. Excess application of sealant may cause part misalignment and oil leaks.

18. Inspect the silicone bead across the top of the aluminum carrier at the oil pan, in the cylinder block, and to the timing chain housing three way joint. Repair a damaged bead using the Silicone Rubber Sealant GM P/N 12345739 (Canadian P/N 10953541) or the equivalent.