GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • EN 46327 Timing Chain Retention Tool
    • J 45059 Angle Meter
    • J 44212 Camshaft Holding Tool

Removal Procedure

  1. Remove the left camshaft cover. Refer to Camshaft Cover Replacement - Left Side .

  2. Object Number: 517149  Size: SH
  3. Rotate the crankshaft to TDC of the # 1 cylinders compression stroke, both camshaft sprocket drive pins should be at the top of their rotation.
  4. Caution: Refer to Camshaft Holding Tool Caution in the Preface section.


    Object Number: 650538  Size: SH
  5. Install the J 44212 over the camshafts.

  6. Object Number: 1275692  Size: SH
  7. Use a paint stick to create a mark (1) on the timing chain link adjacent to each camshaft sprocket timing mark (2, 3).

  8. Object Number: 1275725  Size: SH
  9. Install both EN 46327  (1) to the engine using the following step:
  10. Rotate the wing nut (2) of the EN 46327  (3) to the top of its travel.


    Object Number: 1275702  Size: SH
  11. Position the bottom retention tool on the cylinder head with the V-notch of the block (1) adjacent to the left exhaust camshaft sprocket and chain.

  12. Object Number: 1275713  Size: SH
  13. Insert the hook end (2) into a secondary timing chain link as shown.

  14. Object Number: 1275702  Size: SH
  15. Rotate the wing nut until it contacts the retention tool block (1). DO NOT tighten the wing nut at this time.

  16. Object Number: 1275725  Size: SH
  17. Rotate the wing nut (2) of the EN 46327  (4) to the top of its travel.

  18. Object Number: 1275703  Size: SH
  19. Position the top retention tool on the cylinder head with the V-notch of the block (1) adjacent to the left intake camshaft sprocket and chain.

  20. Object Number: 1275718  Size: SH
  21. Insert the hook end (2) into a secondary timing chain link as shown.

  22. Object Number: 1275703  Size: SH
  23. Rotate the wing nut until it contacts the retention tool block (1). Alternately tighten both wing nuts to retain the chain.
  24. Notice: Refer to Torque Reaction Against Timing Drive Chain Notice in the Preface section.


    Object Number: 749356  Size: SH
  25. Use an open wrench on the hex cast into the camshafts in order to prevent the camshafts from rotating when removing the camshaft sprocket bolts.
  26. Remove the camshaft sprocket bolts.
  27. Remove the camshaft sprockets.

  28. Object Number: 522860  Size: SH
  29. Alternately loosen the camshaft bearing cap bolts a few turns at a time until all valve spring pressure has been released.
  30. Remove the camshaft bearing caps.
  31. Remove the J 44212 from the camshafts.

  32. Object Number: 591912  Size: SH
  33. Remove the camshafts.

  34. Object Number: 609690  Size: SH
  35. Remove the camshaft followers.
  36. Clean and inspect the camshafts. Refer to Camshaft Cleaning and Inspection .

Installation Procedure


    Object Number: 235196  Size: SH
  1. Apply a liberal amount of lubricant to the roller pivot pocket (2) and valve slot areas (1) of the camshaft followers. Refer to Adhesives, Fluids, Lubricants, and Sealers .

  2. Object Number: 522872  Size: SH

    Important: The follower must be positioned squarely on the valve tip so that the full width of the roller will completely contact the camshaft lobe. If the followers are being reused you must put them back in their original location.

  3. Place the camshaft followers in position on the valve tip and the stationary hydraulic lash adjusters (SHLA) (1). The rounded head of the follower goes on the SHLA, while the flat end goes on the valve tip.
  4. Clean the camshaft carriers with a clean, lint-free cloth.

  5. Object Number: 522807  Size: SH
  6. Apply a liberal amount of lubricant to the camshaft carriers, camshaft lobes (1) and the camshaft journals (2). Refer to Adhesives, Fluids, Lubricants, and Sealers .
  7. Place the camshaft in the camshaft carriers with the camshaft sprocket drive pins near the top of their rotation and the camshaft lobes in a neutral position. The camshafts can be identified by a stamping near the rear journal. For example: L-EXH is defined as Left bank Exhaust.

  8. Object Number: 53008  Size: SH
  9. Observe the markings on the camshaft bearing caps. Each camshaft bearing cap is marked in order to identify its location. The markings have the following meanings:
  10. • The arrow should point to the front of the engine.
    • The number indicates the position from the front of the engine.
    • The "E" indicates the exhaust camshaft.
    • The "I" indicates the Intake camshaft.
  11. Apply a liberal amount of lubricant to the camshaft bearing caps. Refer to Adhesives, Fluids, Lubricants, and Sealers .

  12. Object Number: 522860  Size: SH
  13. Install the camshaft bearing caps according to the identification marks.
  14. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 522804  Size: SH
  15. Install the camshaft bearing cap bolts in sequence.
  16. Tighten

    1. Alternately hand tighten the camshaft bearing cap bolts a few turns at a time until all caps are fully seated.
    2. Tighten the camshaft bearing cap bolts to 5 N·m (44 lb in).
    3. Tighten the camshaft bearing cap bolts an additional 30 degrees using the J 45059

    Notice: Refer to Torque Reaction Against Timing Drive Chain Notice in the Preface section.

  17. Align the camshafts.
  18. Caution: Refer to Camshaft Holding Tool Caution in the Preface section.


    Object Number: 650538  Size: SH
  19. Install the J 44212 over the camshafts.
  20. Important: Ensure the camshaft sprockets properly engage the camshaft sprocket drive pins and camshafts.

  21. Install the intake and exhaust camshaft sprockets aligning the paint marks made during disassembly. Ensure that the camshaft sprockets align with the pins of the camshafts.

  22. Object Number: 749356  Size: SH
  23. Use an open wrench on the hex cast into the camshafts in order to prevent the camshafts from rotating when tightening the camshaft sprocket bolts.

  24. Object Number: 650547  Size: SH
  25. Install the camshaft sprocket bolts.
  26. Tighten
    Tighten the camshaft sprocket bolts to 120 N·m (89 lb ft).


    Object Number: 1275725  Size: SH
  27. Remove the EN 46327  (1).

  28. Object Number: 517149  Size: SH
  29. Verify the camshaft sprocket alignment.

  30. Object Number: 650538  Size: SH
  31. Remove the J 44212 from the camshafts.
  32. Install the left camshaft cover. Refer to Camshaft Cover Replacement - Left Side .