GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 45027 Tensioner Tool

Removal Procedure

  1. Remove the camshaft cover. Refer to Camshaft Cover Replacement .
  2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
  3. Remove the No. 1 cylinder spark plug. Refer to Spark Plug Replacement .
  4. Rotate the crankshaft in the engine rotational direction clockwise, until the No. 1 piston is at top dead center (TDC) on the compression stroke.
  5. Remove the engine front cover. Refer to Engine Front Cover Replacement .
  6. Lower the vehicle.

  7. Object Number: 412158  Size: SH

    Important: The timing chain tensioner must be removed to unload chain tension before the timing chain is removed. If not removed, the timing chain will become cocked and it will be difficult to remove.

  8. Remove the timing chain tensioner.

  9. Object Number: 412164  Size: SH
  10. Remove the fixed timing chain guide access plug.

  11. Object Number: 412165  Size: SH
  12. Remove the fixed timing chain guide.

  13. Object Number: 758269  Size: SH
  14. Remove the upper timing chain guide.

  15. Object Number: 412536  Size: SH
  16. Use a 24 mm wrench to hold the camshafts from turning.

  17. Object Number: 412168  Size: SH
  18. Remove the exhaust camshaft sprocket bolt and discard.
  19. Remove the exhaust camshaft sprocket.

  20. Object Number: 412160  Size: SH
  21. Remove the timing chain tensioner guide.

  22. Object Number: 412169  Size: SH
  23. Remove the intake camshaft sprocket bolt and discard.
  24. Remove the intake camshaft sprocket.
  25. Remove the timing chain through the top of the cylinder head.

  26. Object Number: 758277  Size: SH
  27. Remove the crankshaft sprocket.

  28. Object Number: 412200  Size: SH
  29. Remove the oil nozzle and bolt.

  30. Object Number: 412201  Size: SH
  31. Remove the balance shaft drive chain tensioner.

  32. Object Number: 412413  Size: SH
  33. Remove the adjustable balance shaft chain guide.

  34. Object Number: 412414  Size: SH
  35. Remove the small balance shaft drive chain guide.

  36. Object Number: 412415  Size: SH
  37. Remove the upper balance shaft drive chain guide.

  38. Object Number: 412417  Size: SH

    Important: It may ease removal of the balance shaft drive chain to get all of the slack in the chain between the crankshaft and water pump sprockets.

  39. Remove the balance shaft drive chain.

Installation Procedure

    Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 412415  Size: SH

    Important: If the balance shafts are not properly timed to the engine, the engine may vibrate and make noise.

  1. Install the upper balance shaft chain guide.
  2. Tighten
    Tighten the upper balance shaft chain guide bolts to 15 N·m (133 lb in).


    Object Number: 412520  Size: SH
  3. Install the balance shaft drive chain with the colored links lined up on with the marks on the balance shaft drive sprockets and the crankshaft sprocket. Use the following procedure to line up the links with the sprockets:
  4. Orient the chain so that the copper colored and chrome links are visible.

    2.1. Place the uniquely colored link (1) so that it lines up with the timing mark on the intake side balance shaft sprocket.
    2.2. Working clockwise around the chain, place the first matching colored link (2) in line with the timing mark on the crankshaft drive sprocket. (approximately 5 o'clock position on the crank sprocket).
    2.3. Place the chain (3) on the water pump drive sprocket (alignment is not critical).
    2.4. Align the last matching colored link (4) with the timing mark on the exhaust side balance shaft drive sprocket.

    Object Number: 412414  Size: SH
  5. Install the small balance shaft chain guide.
  6. Tighten the balance shaft chain guide bolts.
  7. Tighten
    Tighten the chain guide bolts to 10 N·m (89 lb in).


    Object Number: 412413  Size: SH
  8. Install the adjustable balance shaft drive chain guide.
  9. Tighten
    Tighten the chain guide bolts to 10 N·m (89 lb in).


    Object Number: 412528  Size: SH
  10. Turn the tensioner plunger 90 degrees in its bore. Compress the plunger until a paper clip can be inserted through the hole in the plunger body and into the hole in the tensioner plunger.
  11. Install the timing chain tensioner.
  12. Tighten the chain tensioner bolts.
  13. Tighten
    Tighten the chain tensioner bolts to 10 N·m (89 lb in).

  14. Remove the paper clip from the balance shaft drive chain tensioner.

  15. Object Number: 412200  Size: SH
  16. Install the oil nozzle and bolt.
  17. Tighten
    Tighten the oil nozzle bolt to 10 N·m (89 lb in).


    Object Number: 466551  Size: SH
  18. Install the crankshaft sprocket with timing mark at the 5 o'clock position.

  19. Object Number: 412535  Size: SH
  20. Lower the timing chain through the opening in the top of the cylinder head. Carefully ensure that the chain goes around both sides of the cylinder block bosses (1, 2).

  21. Object Number: 466558  Size: SH
  22. Install the intake camshaft sprocket with the INT diamond at the 2 o'clock position.
  23. Important: Always install NEW sprocket bolts.

  24. Hand tighten a NEW intake camshaft sprocket bolt.
  25. Route the timing chain around the crankshaft sprocket with the matching colored link aligning with the timing mark.
  26. Route the timing chain around the intake camshaft sprocket with the uniquely colored link (1) aligning with the INT diamond.

  27. Object Number: 412160  Size: SH
  28. Install the timing chain tensioner guide through the opening in the top of the cylinder head.
  29. Tighten
    Tighten the timing chain tensioner guide bolt to 10 N·m (89 lb in).


    Object Number: 466570  Size: SH
  30. Install the exhaust camshaft sprocket with the timing chain matching colored link (3) at EXH triangle aligned at the 10 o'clock position.

  31. Object Number: 412536  Size: SH
  32. Use a 24 mm wrench to rotate the camshaft slightly, until exhaust sprocket aligns with the camshaft.
  33. Important: Always install NEW sprocket bolts.

  34. Hand tighten the NEW exhaust camshaft sprocket bolt.

  35. Object Number: 412165  Size: SH
  36. Install the fixed timing chain guide.
  37. Tighten
    Tighten the fixed timing chain bolts to 15 N·m (133 lb in).


    Object Number: 412164  Size: SH
  38. Apply sealant compound to thread and install the timing chain guide bolt access hole plug. Refer to Adhesives, Fluids, Lubricants, and Sealers for the correct part number.
  39. Tighten
    Tighten the chain guide plug to 90 N·m (59 lb ft).


    Object Number: 412167  Size: SH
  40. Install the timing chain upper guide.
  41. Tighten
    Tighten the timing chain upper guide bolts to 10 N·m (89 lb in).


    Object Number: 714496  Size: SH
  42. Inspect the timing chain tensioner. If the timing chain tensioner, O-ring seal, or washer is damaged, replace the timing chain tensioner.
  43. Measure the timing chain tensioner assembly from end to end.
  44. 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.


    Object Number: 797246  Size: SH
  45. If the timing chain tensioner is not in the compressed state, perform the following steps:
  46. 26.1. Remove the piston assembly from the body of the timing chain tensioner by pulling it out.
    26.2. Install the J 45027-2 (2) into a vise.
    26.3. Install the notch end of the piston assembly into the J 45027-2 (2).
    26.4. Using the J 45027-1 (1), turn the ratchet cylinder into the piston.

    Object Number: 714496  Size: SH
  47. Inspect the bore of the tensioner body for dirt, debris, and damage. If any damage appears, replace the tensioner. Clean dirt or debris out with a lint-free cloth.
  48. Install the compressed piston assembly back into the timing chain tensioner body until it stops at the bottom of the bore. Do not compress the piston assembly against the bottom of the bore. If the piston assembly is compressed against the bottom of the bore, it will activate the tensioner, which will then need to be reset again.
  49. 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 26.1 through 26.4.

  50. Object Number: 412158  Size: SH
  51. Install the timing chain tensioner.
  52. Tighten
    Tighten the timing chain tensioner to 75 N·m (55 lb ft).

  53. Use a suitable tool with a rubber tip on the end. Feed the tool down through the camshaft drive chain to rest on the timing chain. Then give a sharp jolt diagonally downwards to release the tensioner.

  54. Object Number: 630311  Size: SH
  55. Use a 24 mm wrench to hold the camshaft.
  56. Tighten
    Tighten the NEW camshaft bolts to 85 N·m (63 lb ft) plus 30 degrees.

  57. Install the camshaft cover. Refer to Camshaft Cover Replacement .
  58. Raise the vehicle. Refer to Lifting and Jacking the Vehicle .
  59. Install the engine front cover. Refer to Engine Front Cover Replacement .
  60. Lower the vehicle.
  61. Connect negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .