Tools Required

J 45059  Angle Meter. See Special Tools .

Fig 1: View Of Crankshaft Sprocket Timing Mark
Courtesy of GENERAL MOTORS CORP.
1. Install the timing chain drive sprocket to the crankshaft with the timing mark in the 5 o'clock position.
Fig 2: Aligning Timing Chain Link & Intake Sprocket Timing Mark
Courtesy of GENERAL MOTORS CORP.
IMPORTANT:
• There are 3 colored links on the timing chain. Two links are of matching color, and one link is of a unique color. Use the following procedure to line up the links with the sprockets. Orient the chain so that the colored links are visible.
• Always use new sprocket bolts.
2. Assemble the intake camshaft sprocket to the timing chain with the timing mark lined up with the uniquely colored link (1). Hand tighten a new intake camshaft sprocket bolt.
Fig 3: Locating Cylinder Block Bosses
Courtesy of GENERAL MOTORS CORP.
3. Lower the timing chain through the opening in the cylinder head. Use care to ensure that the chain goes around both sides of the cylinder block bosses (1, 2).
Fig 4: Identifying Timing Chain Colored Link & Crankshaft Sprocket Timing Mark
Courtesy of GENERAL MOTORS CORP.
4. Route the timing chain around the crankshaft sprocket and line up the first matching colored link (2) with the timing mark on the crankshaft sprocket, in approximately the 5 o'clock position.
Fig 5: View Of Timing Chain Tensioner Guide
Courtesy of GENERAL MOTORS CORP.
NOTE: Refer to FASTENER NOTICE .
5. Install the adjustable timing chain guide through the opening in the cylinder head and install the adjustable timing chain bolt.

   Tighten:  Tighten the adjustable timing chain guide bolt to 10 N.m (89 lb in).

Fig 6: Identifying Exhaust Camshaft Sprocket
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IMPORTANT: Always install new sprocket bolts.
6. Install the exhaust camshaft sprocket and a new bolt loosely onto the exhaust camshaft.
Fig 7: Aligning Timing Chain Link & Exhaust Timing Mark
Courtesy of GENERAL MOTORS CORP.
7. Align the timing mark on the sprocket with the last matching colored link (3). Install the bolt finger tight.
Fig 8: Using 24 mm Wrench To Align Camshaft
Courtesy of GENERAL MOTORS CORP.
NOTE: Do not rotate either camshaft more than half turn in either direction with crankshaft at top dead center (TDC). To do so may cause valve to piston contact resulting in a damaged valve and/or a damaged piston.
8. If the camshaft is 180 degrees out of time, use the following procedure to re-align the cam.

   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.

   1. Turn the crankshaft 45 degrees in either direction.
   2. Turn the intake cam to the appropriate location.
   3. Turn the crankshaft back to top dead center.
9. When the sprocket seats on the cam, tighten the sprocket bolt hand tight.
10. 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.
Fig 9: View Of Fixed Timing Chain Guide
Courtesy of GENERAL MOTORS CORP.
11. Install the fixed timing chain guide.

    Tighten:  Tighten the fixed timing chain guide bolts to 15 N.m (11 lb ft).

Fig 10: View Of Upper Timing Chain Guide
Courtesy of GENERAL MOTORS CORP.
12. Install the upper timing chain guide.

    Tighten:  Tighten the upper timing chain guide bolts to 10 N.m (89 lb in).

Fig 11: Holding Camshaft Stationary With Wrench On Hex Casting On Camshaft
Courtesy of GENERAL MOTORS CORP.
13. Using a 24 mm wrench, engage the hex on the intake camshaft and using a torque wrench, tighten the camshaft sprocket bolt.

    Tighten:  Tighten the intake camshaft sprocket bolt to 85 N.m (63 lb ft), plus 30 degrees using the J 45059  . See Special Tools .

14. Using a 24 mm wrench, engage the hex on the exhaust camshaft and using a torque wrench, tighten the camshaft sprocket bolt.

    Tighten:  Tighten the exhaust camshaft sprocket bolt to 85 N.m (63 lb ft), plus 30 degrees using the J 45059  . See Special Tools .

Fig 12: Measuring Timing Chain Tensioner Assembly
Courtesy of GENERAL MOTORS CORP.
15. Inspect the timing chain tensioner seal. If the timing chain tensioner seal is damaged, replace the timing chain tensioner seal.
16. Measure the timing chain tensioner assembly from end to end.

    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.

17. If the timing chain tensioner is not in the compressed state, simply push in, twist, and lock by hand.
Fig 13: Identifying Timing Chain Tensioner
Courtesy of GENERAL MOTORS CORP.
18. Inspect to ensure all dirt and debris is removed from the timing chain tensioner threaded hole in the cylinder head.
IMPORTANT: Make sure the timing chain tensioner seal is centered throughout the torque procedure to eliminate the possibility of an oil leak.
19. Install the new timing chain tensioner assembly.

    Tighten:  Tighten the timing chain tensioner to 75 N.m (55 lb ft).

20. The timing chain tensioner is released by compressing it 2 mm (0.079 in) which will release the locking mechanism in the ratchet. To release the timing chain tensioner, use a suitable tool with a rubber tip on the end. Feed the tool down through the cam drive chest to rest on the cam chain. Then give a sharp jolt diagonally downwards to release the tensioner.
Fig 14: View Of Oil Nozzle & Bolt
Courtesy of GENERAL MOTORS CORP.
21. Install the timing chain oiling nozzle.

    Tighten:  Tighten the timing chain oiling nozzle bolt to 10 N.m (89 lb in).

Fig 15: View Of Fixed Timing Chain Guide Access Plug
Courtesy of GENERAL MOTORS CORP.
22. Apply sealant GM P/N 12345382 (Canadian P/N 10953489) or equivalent to the thread, and install the timing chain guide bolt access hole plug.

    Tighten:  Tighten the access hole plug to 90 N.m (66 lb ft).