Withdrawal
1. Remove the oil pump.
2. Rotate the crankshaft until the alignment marks are aligned (1) And (2) on the camshaft and crankshaft sprockets.
Caution: Do not rotate the crankshaft with the timing chain removed to prevent the pistons from contacting the valves.
Early model engines and LC9/LMG/LY5 engines
3. Remove the bolt (206) camshaft sprocket mounting.
4. Remove the sprocket (205) camshaft with chain (208).
5. Remove the bolts (231) securing the chain tensioner and remove the tensioner (232).
Late model LY6/L76 and L92 engines
5. Remove the clutch of the variable valve timing system.
All engines
6. Using a puller, remove the crankshaft sprocket.
7. If necessary, remove the crankshaft nose key.
Installation
1. If removed, install the crankshaft nose key as shown.
2. Install the crankshaft sprocket by aligning the sprocket keyway with the key.
3. Using a special mandrel, press the sprocket onto the crankshaft until it stops with the sprocket into the shaft flange.
Early model engines and LC9/LMG/LY5 engines
4. Compress the chain tensioner and secure it with a suitable pin.
5. Install the tensioner on the block and tighten the mounting bolts. Tightening torque 25 Nm.
6. Position the camshaft sprocket so that the alignment mark is in position "6 hours".
7. Install sprocket, chain and sprocket bolt.
8. Check up correctness of combination of adjusting labels on asterisks of distributive and cranked shaft.
9. Remove the fixing pin of the chain tensioner.
10. Tighten the camshaft sprocket bolt. Tightening torque: 1st pass 90 Nm; Tighten the 2nd pass by 40°.
11. Install the oil pump.
Late model LY6/L76 and L92 engines
4. Establish the coupling of system of change of phases of gas distribution.
5. Install the oil pump.