GM Service Manual Online
For 1990-2009 cars only

Removal Procedure


    Object Number: 2017567  Size: SH
  1. Remove the right engine under cover.
  2. Remove the engine cover. Refer to Engine Cover Replacement.
  3. Remove the ignition coil assembly. Refer to Ignition Coil Replacement.
  4. Remove the spark plug. Refer to Spark Plug Replacement.
  5. Remove the 2 ventilation hoses (1, 2) from the cylinder head cover sub-assembly.

  6. Object Number: 2017568  Size: SH
  7. Remove the 2 bolts (1, 2) and separate the 2 wire harness brackets.

  8. Object Number: 2017569  Size: SH
  9. Remove the 8 bolts (1-7, 9) and 2 nuts (8, 10), then remove the cylinder head cover sub-assembly and gasket.

  10. Object Number: 2017570  Size: SH
  11. Set No. 1 cylinder to TDC/compression by turning the crankshaft pulley until the groove (5) and the timing mark "0" on the timing chain cover are aligned.
  12. Check that each timing mark on the camshaft timing gear (4, 6) and sprocket is aligned with each timing mark located on the bearing caps (1, 2) , as shown in the illustration.
  13. If not, turn the crankshaft pulley by 1 revolution (360°) to align the timing marks as illustrated.
  14. Place paint marks on the chain (3, 7) in alignment with the timing marks on the camshaft timing gear and camshaft timing sprocket.
  15. Remove the chain tensioner assembly.

  16. Object Number: 2017572  Size: SH
  17. Loosen the camshaft timing gear or sprocket. While holding the exhaust camshaft with a wrench (2), loosen the No. 2 camshaft timing set bolt.

  18. Object Number: 2017573  Size: SH
  19. Remove the exhaust camshaft using several steps, uniformly loosen and remove the 10 bearing cap bolts in the sequence shown in the illustration.
  20. Remove the 5 bearing caps.

  21. Object Number: 2017575  Size: SH
  22. While holding the exhaust camshaft by hand, remove the camshaft timing sprocket set bolt (1).
  23. Remove the camshaft timing sprocket from the exhaust camshaft with the timing chain wrapped on the sprocket.
  24. Remove the camshaft timing sprocket from the timing chain.

  25. Object Number: 2017576  Size: SH
  26. Remove the intake camshaft using several steps, uniformly loosen and remove the 10 bearing caps bolts in the sequence shown in the illustration.
  27. Remove the 5 bearing caps.
  28. Remove the camshaft and camshaft timing gear assembly while holding the timing chain by hand.

  29. Object Number: 2017577  Size: SH

    Note: Be careful not to drop anything inside the timing chain cover.

  30. Support the timing chain with a string to prevent it from slipping off the crankshaft sprocket as shown in the illustration.

  31. Object Number: 2017579  Size: MH
  32. Remove camshaft timing gear assembly by clamping the camshaft in a vise, and make sure that the camshaft timing gear assembly does not rotate.
  33. Cover all the oil path with vinyl tape except the advance side path (1) shown in the illustration.

  34. Object Number: 2017580  Size: SH

    Note: Cover the paths with a piece of cloth to avoid oil splashes.

  35. Apply air pressure of 150 kPa (22 psi) to the oil path, then turn the camshaft timing gear assembly to the advance direction (counterclockwise) by hand.

  36. Object Number: 2017581  Size: SH

    Note: Be sure not to remove the other 4 bolts. When reusing the camshaft timing gear, release the straight pin lock first, then install the gear.

    Note: Depending on the air pressure, the camshaft timing gear assembly may turn to the advance side without applying force by hand. Also, if the pressure is difficult to apply because of air leakage from the port, the lock pin may be difficult to release.

  37. Remove the flange bolt of the camshaft timing gear.

Inspection Procedure


    Object Number: 2017582  Size: MH
  1. Inspect camshaft timing gear assembly as follows.
  2. 1.1. Install the camshaft timing gear assembly.
    1.2. Clamp the camshaft in a vise, and make sure that the camshaft timing gear assembly does not rotate.
  3. Cover all the oil paths with vinyl tape except the advance side path (1) shown in the illustration.

  4. Object Number: 2017580  Size: SH

    Note: Cover the paths with a piece of cloth to avoid oil splashes.

  5. Apply air pressure of 150 kPa (22 psi) to the oil path.
  6. Note: Depending on the air pressure, the camshaft timing gear may turn to the advance side without applying force by hand. Also, if enough air pressure cannot be applied because of air leakage from the path, releasing the lock pin may be difficult.

  7. Check that the camshaft timing gear revolves in the advance direction (counterclockwise) by hand.
  8. Note: Do not use air pressure to perform the smooth rotation check.

  9. Check for smooth rotation. Turn the camshaft timing gear within its movable range (21°) 2 or 3 times, but do not turn it to the most retarded position. Make sure that the gear turns smoothly.
  10. Check the lock in the most retarded position. Confirm that the camshaft timing gear is locked at the most retarded position.
  11. Remove the camshaft timing gear assembly.

Installation Procedure


    Object Number: 2017583  Size: SH
  1. Install camshaft timing gear assembly by putting the camshaft timing gear and camshaft together with the straight pin (1) and key groove misaligned, as shown in the illustration.

  2. Object Number: 2017584  Size: SH

    Note: Be sure not to turn the camshaft timing gear to the retard direction (clockwise).

  3. Turn the camshaft timing gear as shown in the illustration while pushing it gently against the camshaft. Push further at the position where the pin fits (1) into the groove.
  4. Check that there is no clearance between the gear flange and camshaft.

  5. Object Number: 2017586  Size: SH
  6. Check that there is no clearance (1) between the gear flange and camshaft.
  7. Caution: Refer to Fastener Caution in the Preface section.


    Object Number: 2017587  Size: SH
  8. Install the flange bolt (1) with the camshaft timing gear assembly fixed in place and tighten to 54 N·m (40 lb ft).

  9. Object Number: 2017588  Size: SH
  10. Check that the camshaft timing gear assembly can move to the retard direction (clockwise) and is locked in the most retarded position.

  11. Object Number: 2017591  Size: SH
  12. Apply a light coat of engine oil to the journal portion of the intake camshaft.
  13. Install the timing chain onto the camshaft timing gear with the paint mark (1) aligned with the timing mark on the camshaft timing gear as shown in the illustration.

  14. Object Number: 2017592  Size: SH
  15. Examine the front marks and numbers, and check that the order is as shown in the illustration. Then install the bearing caps into the cylinder head.
  16. Apply a light coat of engine oil on the threads and under the heads of the bearing cap bolts.

  17. Object Number: 2017594  Size: SH
  18. Using several steps, uniformly install the 10 bearing cap bolts (1) in the sequence shown in the illustration and tighten.
  19. • The thrust bearing bolts to 30 N·m (22 lb ft)
    • The remaining bearing bolts to 9.0 N·m (80 lb in)

    Object Number: 2017595  Size: SH
  20. Install the exhaust camshaft.
  21. 12.1. Apply a light coat of engine oil to the journal portion of the exhaust camshaft.
    12.2. Put the exhaust camshaft on the cylinder head with the paint mark (1) on the chain aligned with the timing mark (2) on the camshaft timing sprocket.

    Object Number: 2017597  Size: SH
  22. While holding the exhaust camshaft (1) by hand, temporarily tighten the camshaft timing sprocket set bolt (2).

  23. Object Number: 2017598  Size: SH
  24. Examine the front marks and numbers, and check that the order is as shown in the illustration. Then install the bearing caps onto the cylinder head.
  25. Apply a light coat of engine oil to the threads and under the heads of the bearing cap bolts.

  26. Object Number: 2017599  Size: SH
  27. Using several steps, uniformly install the 10 bearing cap bolts (1) in the sequence shown in the illustration and tighten.
  28. • The thrust bearing bolts to 30 N·m (22 lb ft)
    • The remaining bearing bolts to 9.0 N·m (80 lb in)

    Object Number: 2017600  Size: SH
  29. While holding the exhaust camshaft with a wrench (2), tighten the camshaft timing sprocket set bolt to 54 N·m (40 lb ft).

  30. Object Number: 2017602  Size: SH
  31. Check that the paint marks on the chain are aligned with the timing marks (1, 2) on the camshaft timing gear and camshaft timing sprocket. Also, check that the crankshaft pulley groove (4) is aligned with the timing mark 0 on the timing mark chain cover.

  32. Object Number: 2017603  Size: SH
  33. Install the chain tensioner assembly. Release the ratchet pawl, then fully push in the plunger and hook the hook (1) to the pin (2) so that the plunger is in the position shown in the illustration.

  34. Object Number: 2017604  Size: SH

    Note: When installing the chain tensioner, set the hook again if the hook releases the plunger.

  35. Install a new gasket and chain tensioner with the 2 nuts and tighten to 9.0 N·m (80 lb in).

  36. Object Number: 2017605  Size: SH
  37. Turn the crankshaft counterclockwise, then disconnect the plunger knock pin (2) from the hook (1).

  38. Object Number: 2017606  Size: SH
  39. Turn the crankshaft clockwise, then check that the plunger (1) is extended.
  40. Set the No. 1 cylinder to TDC/compression.
  41. Check the valve clearance. Refer to Valve Clearance Adjustment.

  42. Object Number: 2017607  Size: SH
  43. Remove any old packing material from the contact surface.
  44. Install the cylinder head cover gasket with the 8 bolts (1) and 2 nuts (3) and tighten.
  45. • Bolts 1 to 11 N·m (8 lb ft)
    • Bolts 2 to 14 N·m (10 lb ft)
    • Nuts to 11 N·m (8 lb ft)

    Object Number: 2017568  Size: SH
  46. Install the 2 engine wire harness brackets with the 2 bolts (1, 2) and tighten to 8.4 N·m (74 lb in).

  47. Object Number: 2017567  Size: SH
  48. Connect the 2 ventilation hoses (1, 2) to the cylinder head cover.
  49. Install the spark plug. Refer to Spark Plug Replacement.
  50. Install the ignition coil assembly. Refer to Ignition Coil Replacement.
  51. Inspect for oil leak.
  52. Inspect the ignition timing.
  53. Install the engine cover. Refer to Engine Cover Replacement.
  54. Install the engine under right cover.