GM Service Manual Online
For 1990-2009 cars only

Special Tools

    • EN 46111 Crankshaft Rotation Socket
    • EN 46105 Camshaft Locking Tool
    • EN 46112 Tensioner Retraction Pins

Removal Procedure


    Object Number: 1796475  Size: SH

    Important: After removing the upper intake manifold, and spark plugs, plug any openings to prevent dirt and other contaminants from entering.

  1. Remove the engine front cover assembly. Refer to Engine Front Cover Replacement.
  2. Remove the spark plugs to aid crankshaft or engine rotation.
  3. Install EN 46111  (1) onto the crankshaft (2).

  4. Object Number: 1796477  Size: SH
  5. Using EN 46111  (1), rotate the crankshaft in a clockwise direction until the crankshaft sprocket timing mark (2) is aligned with the indexing mark (3) on the oil pump housing.

  6. Object Number: 1796478  Size: SH
  7. After aligning the crankshaft sprocket timing mark, check that the camshaft flats (1) at the rear of the bank 1 cylinder head are parallel with the cylinder head cover rail (2).
  8. If the camshaft flats are not as shown, rotate the crankshaft 360 degrees.

  9. Object Number: 1796480  Size: SH
  10. Install EN-46105-1 (1) onto the rear of the bank 1 cylinder head camshafts (2).

  11. Object Number: 1796486  Size: SH
  12. Install EN-46105-2 (1) onto the rear of the bank 2 cylinder head camshafts (2).

  13. Object Number: 1796488  Size: SH

    Important: Take care when removing the tensioner bolts. The tensioner plunger is subjected to spring tension and may spring apart during tensioner removal.

  14. Remove the bank 1 secondary timing chain tensioner bolts (1) and remove the tensioner (2).

  15. Object Number: 1796490  Size: SH
  16. Remove the tensioner gasket (1) from the tensioner (2) and discard the gasket.
  17. Inspect the tensioner mounting surface on the bank 1 cylinder head for burrs or any defects that would affect the sealing of a new tensioner gasket.

  18. Object Number: 1796494  Size: SH
  19. Remove the bank 1 secondary timing chain shoe bolt (1).

  20. Object Number: 1796502  Size: SH
  21. Remove the bank 1 secondary timing chain shoe (1).

  22. Object Number: 1796504  Size: SH
  23. Remove the two bank 1 secondary timing chain guide bolts (1) and remove the guide (2).

  24. Object Number: 1796506  Size: SH
  25. Remove the bank 1 secondary timing chain (1) from the camshaft position actuators (2) and the camshaft intermediate driveshaft sprocket (3).

Cleaning Procedure

  1. Clean all the following components with a suitable solvent:
  2. • Crankshaft sprocket
    • Primary timing chain
    • Primary timing chain guide
    • Primary timing chain tensioner
    • Secondary timing chains
    • Secondary timing chain shoes
    • Secondary timing chain guides
    • Secondary timing chain tensioners
    • Bolts
  3. Dry all the components with compressed air.

Timing Chains Inspection


    Object Number: 1796647  Size: SH
  1. Inspect the primary and/or secondary timing chains for the following:
  2. • Binding or worn rollers (1)
    • Loose links (2)
    • Loose pins (3)
  3. Replace a damaged timing chain as required.

Camshaft Intermediate Driveshaft Sprockets Inspection


Object Number: 1796653  Size: SH

Inspect the camshaft intermediate driveshaft sprockets for the following:

    • Damage to the primary and secondary timing chain sprocket (1)
    • Damage to the hub bearing (2). Ensure the hub bearing spins freely. If the hub bearing wobbles, is noisy or feels rough when rotated replace the camshaft intermediate sprocket
    • Damage to the bolt flange seating/sealing surface (3)
    • Damage to the bearing hub-to-engine block sealing surface
    • Inspect the camshaft position actuator assemblies.

Crankshaft Sprockets Inspection


    Object Number: 1796655  Size: SH
  1. Inspect the crankshaft sprocket for the following:
  2. • Sprocket damage (1)
    • Bore damage (2)
    • Keyway damage (3)
    • Damage to the cushion material (4)
  3. Replace a damaged sprocket as required.

Primary Timing Chain Upper Guide Inspection


    Object Number: 1796664  Size: SH
  1. Inspect the primary timing chain lower guide for the following:
  2. • Worn guide surface (1)
    • Cracked or broken guide surface (2)
    • Cracked or damaged guide base (3)
  3. Replace a damaged guide as required.

Primary Timing Chain Lower Guide Inspection


    Object Number: 1796680  Size: SH
  1. Inspect the primary timing chain lower guide for the following:
  2. • Worn guide surface (1)
    • Cracked or broken guide surface (2)
    • Cracked or damaged guide base (3)

    Important: The primary timing chain lower guide is not serviced separately and is part of the oil pump assembly.

  3. Replace the primary timing chain lower guide by replacing the oil pump assembly, if necessary. Refer to Oil Pump Replacement.

Primary Timing Chain Tensioner Inspection


    Object Number: 1796683  Size: SH
  1. Inspect the primary timing chain tensioner for worn shoe surface (1).
  2. Inspect the tensioner for a locked or binding tensioner shaft (2). Reset the plunger (3) and ensure the tensioner shaft moves freely in and out of the body of the tensioner
  3. Important: To reset the tensioner, use a suitably sized flat-bladed screwdriver (4) to wind the plunger in a clockwise direction, into the tensioner shaft.

  4. Replace a damaged tensioner as required.

Bank 2 Secondary Timing Chain Guide Inspection


    Object Number: 1796685  Size: SH
  1. Inspect the bank 2 secondary timing chain guide for the following:
  2. • Worn guide surface (1)
    • Cracked or broken guide surface (2)
    • Cracked or damaged guide  (3)
  3. Replace a damaged guide as required. Reset the plunger (3) and ensure the tensioner shaft moves freely in and out of the body of the tensioner.

Bank 2 Secondary Timing Chain Shoe Inspection


    Object Number: 1796687  Size: SH
  1. Inspect the front of the bank 2 secondary timing chain shoe for the following:
  2. • Worn shoe surface (1)
    • Cracked or broken shoe surface (2)
    • Cracked or damaged shoe (3)

    Object Number: 1796691  Size: SH
  3. Inspect the back of the shoe for a damaged, worn or missing timing chain tensioner contact pad (1).
  4. Replace a damaged shoe as required.

Bank 2 Secondary Timing Chain Tensioner Inspection


    Object Number: 1796692  Size: SH
  1. Inspect the bank 2 secondary timing chain tensioner for damaged plunger-to-shoe contact surface (1).
  2. Inspect the tensioner for locked or binding tensioner shaft (2). Reset the plunger (3) and ensure the tensioner shaft moves freely in and out of the body of the tensioner.
  3. Important: To reset the tensioner, use a suitably sized flat-bladed screwdriver (4) to wind the plunger in a clockwise direction, into the tensioner shaft.

  4. Replace a damaged tensioner as required.

Bank 1 Secondary Timing Chain Guide Inspection


    Object Number: 1796693  Size: SH
  1. Inspect the bank 1 secondary timing chain guide for the following:
  2. • Worn guide surface (1)
    • Cracked or broken guide surface (2)
    • Cracked or damaged guide base (3)
  3. Replace a damaged guide as required.

Bank 1 Secondary Timing Chain Shoe Inspection


    Object Number: 1796694  Size: SH
  1. Inspect the front of the bank 1 secondary timing chain shoe for the following:
  2. • Worn shoe surface (1)
    • Cracked or broken shoe surface (2)
    • Cracked or damaged shoe (3)

    Object Number: 1796695  Size: SH
  3. Inspect the back of the shoe for a damaged, worn or missing timing chain tensioner contact pad (1).
  4. Replace a damaged shoe as required.

Bank 1 Secondary Timing Chain Tensioner Inspection

  1. Inspect the bank 1 secondary timing chain tensioner for damaged plunger-to-shoe contact surface  (1).
  2. Important: To reset the tensioner, use a suitably sized flat-bladed screwdriver (4) to wind the plunger in a clockwise direction, into the tensioner shaft.

  3. Inspect the tensioner for a locked or binding tensioner shaft (2). Reset the plunger (3) and ensure the tensioner shaft moves freely in and out of the body of the tensioner.
  4. Replace a damaged tensioner as required.

Installation Procedure


    Object Number: 1796477  Size: SH
  1. Install the primary timing chain components.
  2. Using EN 46111  (1), rotate the crankshaft in a clockwise direction until the crankshaft sprocket timing mark (2) is aligned with the indexing mark (3) on the oil pump housing.

  3. Object Number: 1797015  Size: SH
  4. In order to install EN 46105 onto the camshafts, rotate the camshafts. There should be no need to rotate the camshaft more than 45 degrees.

  5. Object Number: 1796480  Size: SH
  6. Install EN-46105-1 (1) onto the rear of the bank 1 cylinder head camshafts (2).

  7. Object Number: 1796486  Size: SH
  8. Install EN-46105-2 (1) onto the rear of the bank 2 cylinder head camshafts (2).

  9. Object Number: 1796506  Size: SH
  10. Install the bank 1 secondary timing chain (1) onto the camshaft actuators (2) and the right hand camshaft intermediate driveshaft sprocket (3) aligning the chain.

  11. Object Number: 1797310  Size: SH
  12. Place the secondary timing chain around the bank 1 camshaft intermediate driveshaft outer sprocket, aligning the bright plated timing chain link (1) with the alignment access hole (2) in the inner sprocket.

  13. Object Number: 1797311  Size: SH
  14. Wrap the secondary timing chain around both bank 1 actuator drive sprockets.

  15. Object Number: 1797314  Size: SH

    Important: Ensure that when aligning the bank 1 secondary timing chain to the bank 1 camshaft actuator sprockets, that the triangular timing marks (1) on the sprocket are used, NOT the circular mark.

  16. Align the bright plated timing chain link (2) with the exhaust actuator sprocket alignment triangle mark.

  17. Object Number: 1797316  Size: SH
  18. Align the bright plated timing chain link (1) with the intake actuator sprocket alignment triangle mark (2).

  19. Object Number: 1797317  Size: SH

    Important: Ensure that the bank 1 secondary timing chain guide is used when installing to the Bank 1 side in this procedure.

  20. Ensure that the bank 1 secondary timing chain guide is selected and orientated correctly.

  21. Object Number: 1797318  Size: SH
  22. Position the chain guide (2).
  23. Notice: Refer to Fastener Notice in the Preface section.

  24. Ensure the primary timing chain upper guide is selected and orientated correctly.
  25. Tighten
    Tighten the secondary timing chain guide bolts to 23 N·m (17 lb ft).


    Object Number: 1797329  Size: SH

    Important: The bank 1 secondary camshaft drive shoe is marked with the letters ’RH’. Ensure that the bank 1 drive shoe is used when installing to the bank 1 side in this procedure and that the letters ’RH" are facing the front of the vehicle when installed.

  26. Ensure the bank 1 secondary timing chain shoe is selected and orientated correctly.
  27. Position the bank 1 secondary timing chain shoe (1).
  28. Tighten
    Tighten the bank 1 secondary timing chain shoe attaching bolt to 23 N·m (17 lb ft).


    Object Number: 1797331  Size: SH
  29. Ensure the bank 1 secondary timing chain tensioner is selected and orientated correctly.

  30. Object Number: 1797332  Size: SH

    Important: To reset the tensioner, use a suitably sized flat-bladed screwdriver (1) to wind the plunger in a clockwise direction, into the tensioner shaft (2).

  31. Reset the bank 1 secondary timing chain tensioner.

  32. Object Number: 1797340  Size: SH
  33. Install the tensioner shaft (1) into the bank 1 secondary timing chain tensioner body (2).

  34. Object Number: 1797343  Size: SH

    Important: If EN 46112  (1) is not inserted into the tensioner body (2), the plunger will remain in the locked position and no tension will be placed on the timing chain, this will cause damage to the engine.

  35. Compress the tensioner shaft into the body and lock the tensioner by inserting EN 46112 into the access hole in the side of the tensioner body.
  36. Slowly release pressure on the bank 1 secondary timing chain tensioner. The tensioner should remain compressed.

  37. Object Number: 1797347  Size: SH
  38. Install a new bank 1 secondary timing chain tensioner gasket (1) to the tensioner (2).
  39. Install the bank 1 secondary timing chain tensioner bolts (3) through the tensioner and gasket.
  40. Ensure the bank 1 secondary timing chain tensioner mounting surface on the bank 1 cylinder head does not have any burrs or defects that would affect the sealing of the new tensioner gasket.

  41. Object Number: 1796488  Size: SH
  42. Place the bank 1 secondary timing chain tensioner (2) into position and loosely install the bolts (1) to the engine block.

  43. Object Number: 1797351  Size: SH
  44. Verify the proper placement of the bank 1 secondary timing chain tensioner gasket tab (1).
  45. Install the bank 1 secondary timing chain tensioner bolts (2).
  46. Tighten
    Tighten the bank 1 secondary timing chain tensioner bolts to 23 N·m (17 lb ft).


    Object Number: 1797353  Size: SH
  47. Release the bank 1 timing chain tensioner (1) by pulling out EN 46112  (2) and unlocking the tensioner plunger.

  48. Object Number: 1797362  Size: SH
  49. Verify all primary and secondary timing chain timing mark alignments (1-18).
  50. Remove EN 46105 and EN-46105-2 from both of the cylinder head camshafts.
  51. Install the spark plugs. Refer to Spark Plug Replacement.
  52. Install the engine front cover assembly. Refer to Engine Front Cover Replacement .