- Install the timing chain drive sprocket to the crankshaft with the timing mark in the 5 o'clock position.
- Assemble the intake camshaft sprocket to the timing chain with the timing mark lined up with the copper colored link (1). Hand tighten a new intake camshaft sprocket bolt.
- Lower the timing chain through the opening in the cylinder head. Use care to make sure that the chain goes around both sides of the cylinder block bosses (1,2).
- Route the timing chain around the crankshaft sprocket and line up the second silver link (2) with the timing mark on the crankshaft sprocket in about the 5 o'clock position.
- Install the adjustable timing chain guide through the opening in the cylinder head and install the adjustable timing chain bolt.
- Install the exhaust camshaft sprocket and a new bolt loosely onto the exhaust camshaft.
- Align the timing mark on the sprocket with the silver link (3). Install the bolt finger tight.
- Using a 24 mm wrench, first turn the intake camshaft until the alignment feature on the back of the camshaft sprocket seats in the notch in the front of the intake camshaft.
- When the sprocket seats on the cam, tighten the sprocket bolt hand tight.
- Verify that all of the colored links and the appropriate timing marks are still aligned. If they are not, repeat the portion of the procedure necessary to align the timing marks.
- Install the fixed timing chain guide.
- Install the upper timing chain guide.
- Using a 24 mm wrench, engage the hex on the intake camshaft and using a torque wrench, tighten the camshaft sprocket bolt.
- Using a 24 mm wrench, engage the hex on the exhaust camshaft and using a torque wrench, tighten the camshaft sprocket bolt.
- Measure the new timing chain tensioner assembly from end to end.
- Check to see if all thread sealant is removed from the timing chain tensioner threaded hole in the cylinder head.
- Install the new timing chain tensioner assembly.
- The timing chain tensioner is released by compressing it 2 mm (.079 in) which will release the locking mechanism in the ratchet. The tensioner can be released by one of two methods:
- Install the timing chain oiling nozzle.
- Apply sealant, GM P/N 12345382, compound to thread and Install the timing chain guide bolt access hole plug.
Important: Always use new sprocket bolts.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Tighten
Tighten the adjustable timing chain guide bolt to 10 N·m
(89 lb in).
Important: Always install new sprocket bolts.
Important: Do not turn the camshaft more than 1/2 turn in either direction. To do so may cause valve to piston contact. This may damage a valve and/or a piston. If the camshaft is 180 degrees out of time, use the following procedure to re-align the cam.
| 8.1. | Turn the crankshaft 45 degrees in either direction. |
| 8.2. | Turn the intake cam to the appropriate location. |
| 8.3. | Turn the crankshaft back to top dead center. |
Tighten
Tighten the fixed timing chain guide bolts to 10 N·m (89 lb in).
Tighten
Tighten the upper timing chain guide bolts to 10 N·m (89 lb in).
Tighten
Tighten the intake camshaft sprocket bolt to 85 N·m (63 lb ft),
plus 30 degrees using a torque angle meter.
Tighten
Tighten the exhaust camshaft sprocket bolt to 85 N·m (63 lb ft),
plus 30 degrees using a torque angle meter.
A new tensioner should be supplied in the fully compressed non-active state. A tensioner in the compressed state will measure 72 mm (2.83 in) (a) from end to end. A tensioner in the active state will measure 85 mm (3.35 in) (a) from end to end. If the tensioner is not in the compressed state perform the following steps:
| 15.1. | Hold the flat end of the tensioner piston with a wrench. |
| 15.2. | Rotate the piston clockwise by slightly less than one turn at which point resistance will be felt. |
| 15.3. | At this point the tensioner should measure approximately 72 mm (2.83 in) (a) from end to end. If the tensioner does not read 72 mm (2.83 in) (a) from end to end repeat steps 15.1 and 15.2. |
Tighten
Tighten the timing chain tensioner to 75 N·m (55 lb ft).
| 18.1. | If the engine has less than 30,000 miles (48,279 km) the tensioner can be released by starting the engine. This method cannot be used on an engine with over 30,000 miles or the cam chain may jump teeth on the cam sprockets. |
| 18.2. | If the engine has over 30,000 miles (48,279 km) on it use a suitable tool with a rubber tip on the end. Feed the tool down through the cam drive chant to rest on the cam chain. Then give a sharp jolt diagonally downwards to release the tensioner. |
Tighten
Tighten the timing chain oiling nozzle bolt to 10 N·m (89 lb in).
Tighten
Tighten the access hole plug to 40 N·m (30 lb ft).
