GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

  1. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
  2. Remove the No. 1 cylinder spark plug. Refer to Spark Plug Replacement .
  3. Rotate the crankshaft in the engine rotational direction clockwise, until the No. 1 piston is at top dead center (TDC) on the compression stroke.
  4. Remove the front cover. Refer to Engine Front Cover Replacement .

  5. Object Number: 1013303  Size: SH
  6. Remove the camshaft cover assembly. Refer to Camshaft Cover Removal .

  7. Object Number: 894951  Size: SH

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

  8. Remove timing chain tensioner.

  9. Object Number: 894944  Size: SH
  10. Remove the upper timing chain guide.

  11. Object Number: 894960  Size: SH

    Important: The camshaft sprocket bolt is not reusable. It is a torque-to-yield (TTY) bolt, and must be discarded to prevent premature failure.

  12. Remove the exhaust camshaft sprocket and discard the bolt.

  13. Object Number: 894967  Size: SH
  14. Remove the adjustable timing chain guide.

  15. Object Number: 894968  Size: SH
  16. Remove the fixed timing chain guide access plug.

  17. Object Number: 894969  Size: SH
  18. Remove the fixed timing chain guide.

  19. Object Number: 895205  Size: SH

    Important: The camshaft sprocket bolt is not reusable. It is a TTY bolt, and must be discarded to prevent premature failure.

  20. Remove the intake camshaft sprocket and discard the bolt.
  21. Remove the timing chain through the top of the cylinder head.

  22. Object Number: 897597  Size: SH
  23. Remove the timing chain drive sprocket from the crankshaft.

  24. Object Number: 895210  Size: SH
  25. Remove the timing chain oiling nozzle.

  26. Object Number: 895127  Size: SH

    Important: Replace the timing chain guides if wear exceeds 1.12 mm (0.045 in).

  27. Inspect the timing chain guides for cracking or wear.
  28. Important: Replace the timing chain tensioner shoe if wear exceeds 1.12 mm (0.045 in).

  29. Inspect the timing chain tensioner shoe for wear.
  30. Inspect the timing chain and sprockets for wear.
  31. Inspect the camshaft sprocket faces for signs of movement.
  32. Inspect the camshaft sprocket teeth and chain for signs of excessive wear, chipping, or seizure of timing chain links.

Installation Procedure


    Object Number: 895127  Size: SH
  1. Install the timing chain drive sprocket to the crankshaft.
  2. Rotate the crank so that the mark on the sprocket is at the 5 o'clock position.

  3. Object Number: 895009  Size: SH
  4. Assemble the chain to the intake camshaft sprocket alignment copper link to the INT diamond timing mark on the camshaft sprocket.

  5. Object Number: 895010  Size: SH

    Important: When lowering the timing chain rotate the assembly 90 degrees to allow the chain to fall between the cylinder block bosses, then rotate the assembly back so that the camshaft sprocket is facing forward.

  6. Lower the assembly through the chain housing opening on top of the cylinder head. Use care to make sure that the chain goes around both sides of the cylinder block bosses.

  7. Object Number: 895036  Size: SH

    Important: The crankshaft sprocket timing mark will be at approximately the 5 o'clock position.

  8. Route the chain around the crankshaft sprocket and align the silver link to the timing mark.
  9. Important: The camshaft sprocket bolt is not reusable. It is a TTY bolt, and must be discarded to prevent premature failure.

  10. Install the intake camshaft sprocket loosely onto the intake camshaft and install the new camshaft sprocket bolt finger tight. It is not necessary to align the sprocket-to-camshaft offset notch at this time.
  11. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 894967  Size: SH

    Important:  There is a 2nd design adjustable guide with a contact pad for the 2nd design notched tensioner. A 2nd design guide should be used only with 2nd design tensioner.

  12. Install the adjustable timing chain guide through the opening on top of the cylinder head and install the chain guide bolt.
  13. Tighten
    Tighten the timing chain guide (adjustable) bolt to 10 N·m (89 lb in).


    Object Number: 894960  Size: SH
  14. Install the exhaust camshaft sprocket loosely onto the exhaust camshaft with the timing mark on the sprocket aligned with the silver link and install the new camshaft sprocket bolt finger tight. It is not necessary to align the sprocket-to-camshaft offset notch at this time.

  15. Object Number: 895036  Size: SH

    Important: The camshaft sprocket bolt is not reusable. It is a TTY bolt, and must be discarded to prevent premature failure.

  16. Align the camshaft sprocket-to-camshaft and tighten the camshaft bolt using the following procedure:
  17. Notice: 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.

  18. Ensure the sprocket timing mark is at the 5 o'clock position.

  19. Object Number: 895042  Size: SH
  20. Rotate the intake camshaft using a 24 mm wrench on the flats of the camshaft until the sprocket-to-camshaft alignment notch seats.
  21. When the sprocket seats on the camshaft, tighten the sprocket bolt finger tight.
  22. Rotate the exhaust camshaft using a 24 mm wrench on the flats of the camshaft until the sprocket-to-camshaft alignment notch seats.
  23. When the sprocket seats on the camshaft, tighten the sprocket bolt finger tight.

  24. Object Number: 894969  Size: SH
  25. Verify that all colored links are aligned with the appropriate marks on the camshaft and crankshaft sprockets. If they are not, repeat steps 8-10.
  26. Install the fixed timing chain guide and bolts.

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


    Object Number: 894968  Size: SH
  27. Install the fixed timing chain guide bolt access hole plug.
  28. Tighten
    Tighten the timing chain guide bolt access hole plug to 40 N·m (30 lb ft).


    Object Number: 894944  Size: SH
  29. Install the upper timing chain guide and bolts.
  30. Tighten
    Tighten the timing chain guide (upper) bolts to 10 N·m (89 lb in).


    Object Number: 895042  Size: SH

    Notice: Use a 24 mm wrench to support the camshaft while applying torque to camshaft sprocket bolt. Do not torque camshaft bolts against timing chain, as it may damage the timing chain.

  31. Tighten the intake and exhaust camshaft sprocket bolts.
  32. Tighten
    Tighten the camshaft sprocket bolts to 85 N·m (63 lb ft) plus 30 degrees.


    Object Number: 894951  Size: SH

    Important:  There is a 2nd design tensioner with a notch at the plunger end of the tensioner. This tensioner should be used only with the 2nd design adjustable guide.

  33. Install the sealing ring and tensioner assembly.
  34. Tighten
    Tighten the timing chain tensioner to 75 N·m (55 lb ft).


    Object Number: 895210  Size: SH
  35. Install the timing chain oil nozzle and bolt.
  36. Tighten
    Tighten the timing chain oil nozzle bolt to 10 N·m (89 lb in).


    Object Number: 1013303  Size: SH
  37. Install the camshaft cover assembly. Refer to Camshaft Cover Installation .

  38. Object Number: 895054  Size: SH
  39. Install the engine front cover. Refer to Engine Front Cover Replacement .
  40. Connect the negative battery cable.
  41. Tighten
    Tighten the battery terminal bolts to 17 N·m (13 lb ft).