GM Service Manual Online
For 1990-2009 cars only

Special Tools

    • EN-45027 Tensioner Tool
    • EN-45059 Angle Meter
    • EN-48953 Camshaft Actuator Locking Tool

For equivalent regional tools, refer to Special Tools.


    Object Number: 1825076  Size: SH

    Note: The engine is timed top-dead center exhaust stroke.

  1. Ensure the intake camshaft notch is in the 5 o'clock position (2) and the exhaust camshaft notch is in the 7 o'clock position (1). The number 1 piston should be at top dead center (TDC), crankshaft key at 12 o'clock.

  2. Object Number: 2128110  Size: SH
  3. Install a friction washer (1), if equipped.
  4. Install the timing chain drive sprocket (3) to the crankshaft with the timing mark (2) in the 5 o'clock position and the front of the sprocket facing out.
  5. Install a second friction washer (1), if equipped.

  6. Object Number: 1594347  Size: SH

    Note: There are 3 colored links on the timing chain. 2 links are of matching color, and 1 link is of a unique color. Use the following procedure to line up the links with the actuators. Orient the chain so that the colored links are visible.

  7. Assemble the intake camshaft actuator into the timing chain with the timing mark lined up with the uniquely colored link (1).

  8. Object Number: 1825082  Size: SH
  9. 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).
  10. Install the intake camshaft actuator onto the intake camshaft while aligning the dowel pin into the camshaft slot.
  11. Note: Always use NEW actuator bolts.

  12. Hand tighten the new intake camshaft actuator bolt.

  13. Object Number: 2146381  Size: SH
  14. Route the timing chain around the crankshaft sprocket and line up the first matching colored link (1) with the timing mark on the crankshaft sprocket, in approximately the 5 o'clock position.

  15. Object Number: 2146287  Size: SH
  16. Rotate the crankshaft clockwise to remove all chain slack. Do not rotate the intake camshaft.
  17. Caution: Refer to Fastener Caution in the Preface section.

  18. Install the adjustable timing chain guide (1) down through the opening in the cylinder head and install the adjustable timing chain bolt and tighten to 10 N·m  (89 lb in).

  19. Object Number: 2153635  Size: SH
  20. Install the exhaust camshaft actuator (1) into the timing chain with the timing mark lined up with the second matching colored link.

  21. Object Number: 2146382  Size: SH

    Note: Always install NEW actuator bolts.

  22. Install the exhaust camshaft actuator (1) onto the exhaust camshaft, aligning the dowel pin into the camshaft slot.
  23. Using a 23 mm open end wrench, rotate the exhaust camshaft clockwise approximately 45 degrees until the dowel pin in the camshaft actuator goes into the camshaft slot.

  24. Object Number: 2146383  Size: SH
  25. When the actuator seats on the cam, tighten the new exhaust camshaft actuator bolt hand tight.
  26. 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.

  27. Object Number: 2146289  Size: SH
  28. Install the fixed timing chain guide (1) and bolts and tighten to 12 N·m  (106 lb in).

  29. Object Number: 2146284  Size: SH
  30. Install the upper timing chain guide (1) and bolts and tighten to 10 N·m  (89 lb in).

  31. Object Number: 797246  Size: SH
  32. Reset the timing chain tensioner by performing the following steps:
  33. 19.1. Remove the snap ring.
    19.2. Remove the piston assembly from the body of the timing chain tensioner.
    19.3. Install the EN-45027-2  (2) tensioner into a vise.
    19.4. Install the notch end of the piston assembly into the EN-45027-2  (2) tensioner .
    19.5. Using the EN-45027-1 (1) tensioner , turn the ratchet cylinder into the piston.
    19.6. Reinstall the piston assembly into the body of the tensioner.
    19.7. Install the snap ring.

    Object Number: 2146285  Size: SH
  34. Inspect the timing chain tensioner seal for damage. If damaged, replace the seal.
  35. Inspect to ensure all dirt and debris is removed from the timing chain tensioner threaded hole in the cylinder head.
  36. Note: Ensure the timing chain tensioner seal is centered throughout the torque procedure to eliminate the possibility of an oil leak.

    Note: The crankshaft balancer must be installed in order to release the tensioner. Refer to Crankshaft Balancer Installation for tensioner release instructions.

  37. Install the timing chain tensioner assembly (1) and tighten to 75 N·m  (55 lb ft).

  38. Object Number: 2128100  Size: SH
  39. Install EN-48953 locking tool  (1) and tighten the bolts into the cylinder head to 10 N·m (89 lb in).
  40. Using a torque wrench, tighten the camshaft actuator bolt to 30 N·m (22 lb ft) , plus 100 degrees using the EN-45059 meter .
  41. Using a torque wrench, tighten the camshaft actuator bolt to 30 N·m (22 lb ft) , plus 100 degrees using the EN-45059 meter .
  42. Remove EN-48953 locking tool .

  43. Object Number: 2146291  Size: SH
  44. Install the timing chain oiling nozzle (1) and tighten the bolt to 10 N·m (89 lb in).

  45. Object Number: 2146288  Size: SH
  46. Apply sealant to the thread of the timing chain guide bolt access hole plug. Refer to Adhesives, Fluids, Lubricants, and Sealers.
  47. Install the timing chain guide bolt access hole plug (1) and tighten to 75 N·m (55 lb ft).