GM Service Manual Online
For 1990-2009 cars only

    Notice: The timing chain on the LD9 (VIN T) Twin Cam Engine is not to be replaced with the timing chain from any other model year. The timing sprockets are different on the Twin Cam engine and the shape of the links matches the sprockets. Engine damage may result if the wrong timing chain is used. The timing chain and the crankshaft sprocket must be marked so that they are reinstalled in the same side facing out at the time of reassembly.

    Important: Read the entire procedure before removing the timing chain.


    Object Number: 60370  Size: SH
  1. Mark the timing chain and the crankshaft sprocket outer surfaces for reassembly. Ensure that this is done in order to prevent noise and increased wear on the chain.
  2. Remove the timing chain guides.
  3. Reload the timing chain tensioner assembly to its "zero" position. Use the following steps:
  4. 3.1. Form a keeper from a piece of heavy gauge wire.
    3.2. Apply slight force on the tensioner shoe to compress the plunger.
    3.3. Insert a small screwdriver into the reset access hole.
    3.4. Pry the ratchet pawl away from the ratchet teeth while forcing the plunger completely in the hole.
    3.5. Install the keeper between the access hole and the blade.

    Object Number: 33623  Size: SH
  5. Remove the tensioner assembly retaining bolts.
  6. Remove the tensioner. Ensure all of the slack in the timing chain is above the tensioner assembly when the tensioner is removed.

  7. Object Number: 33625  Size: SH
  8. Remove the timing chain.
  9. Inspect the parts for wear, replace them as required.
  10. Replace the timing chain shoe or guides if the scoring exceeds 1.12 mm (0.045 in).