Removal Procedure

Important: 

• Before remove the timing chain, read the entire procedure.
• 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 in order to insure reassembly with the same side facing out at the time of reassembly.

Fig 1: Timing Chain

Courtesy of GENERAL MOTORS CORP.

1. Remove the engine front cover. Refer to Engine Front Cover Replacement .
2. Rotate the crankshaft clockwise (as viewed from the front of the engine, normal rotation) until the camshaft sprocket timing dowel pin holes line up with the holes in the timing chain housing.
3. The crankshaft sprocket keyway should point upwards and line up with the centerline of the cylinder bores. This is the Timed position.
4. Remove the timing chain guides.
5. Raise and support the vehicle.
6. Ensure that all of the slack in the timing chain is above the tensioner assembly.
7. Remove the timing chain tensioner.
8. The timing chain must be disengaged from any wear grooves in the tensioner shoe in order to remove the shoe. Slide a screwdriver blade under the timing chain while pulling the shoe outward.
   NOTE: Do not attempt to pry the sprocket off the camshaft or damage to the sprocket or chain housing could occur.
9. If difficulty is encountered in removing the timing chain tensioner shoe, use the following procedure in order to remove the intake camshaft sprocket:
   1. 9.1. Lower the vehicle.
   2. 9.2. Hold the intake camshaft sprocket with the J 39579  and remove the sprocket bolt and washer.
   3. 9.3. Remove the washer from the bolt and rethread the bolt back into the camshaft by hand (the bolt provides a surface to push against).
10. Remove the intake camshaft sprocket. Use a three-jaw puller in the 3 relief holes in the sprocket.

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

11. Mark the crankshaft sprocket and the timing chain outer surface.
12. Remove the timing chain.
13. Remove camshaft sprocket bolts and sprockets.
Fig 2: Camshaft Sprocket
Courtesy of GENERAL MOTORS CORP.
14. Clean the old sealant off of the bolt with a wire brush.
15. Clean the threaded hole in the camshaft with a round nylon bristle brush.
16. Inspect the parts for wear and replace the parts as necessary. Some scoring of the timing chain shoe and the guides is normal.