GM Service Manual Online
For 1990-2009 cars only

Special Tools

    • J 38185 Hose Clamp Pliers
    • J 45059 Angle Meter
    • EN-48749 Timing Chain Retention Tool Kit
    • EN-48953 Camshaft Actuator Locking Tool

Removal Procedure


    Object Number: 1656126  Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling.
  2. Remove the exhaust manifold. Refer to Exhaust Manifold Replacement.
  3. Remove the intake manifold. Refer to Intake Manifold Replacement.
  4. Reposition the radiator surge tank air bleed hose clamp.
  5. Remove the radiator surge tank air bleed hose from the cylinder head.
  6. Reposition the radiator inlet hose clamp using the J 38185 .
  7. Remove the radiator inlet hose from the cylinder head.
  8. Disconnect all electrical connectors as necessary.
  9. Remove the camshaft cover. Refer to Camshaft Cover Replacement.

  10. Object Number: 1578296  Size: SH
  11. Remove the upper timing chain guide bolts and guide.

  12. Object Number: 2066456  Size: SH

    Note: 

       • If the intake camshaft actuator is moving independently of the camshaft, this means the camshaft is not locked to the actuator. Rotate the camshaft counter-clockwise while the holding tool is installed and this will lock the camshaft to the actuator.
       • Ensure the timing chain and the camshaft position actuators are marked for proper assembly.

  13. Rotate the intake camshaft clockwise and install the EN-48953 (1) to the actuators.
  14. Caution: Refer to Fastener Caution in the Preface section.

  15. Install the camshaft actuator retainer bolts and tighten to 10 N·m (89 lb in).
  16. Clean the timing chain and gears with solvent.
  17. Mark the timing gear sprockets and the timing chain. It is recommended that the paint marks are located in the 12 o'clock position.
  18. Loosen, but do not remove the intake and exhaust camshaft actuator bolts.
  19. Remove the camshaft actuator locking tool, EN-48953 .

  20. Object Number: 2066475  Size: SH

    Note: Ensure the tips of the EN-48749 are fully engaged into the timing chain. The retention tool rod can be used on the back side of the chain to ensure the teeth from the retention tool are engaged.

  21. Install the timing chain retention tool EN-48749 (1) to the intake side of the timing chain.

  22. Object Number: 412158  Size: SH
  23. Remove the timing chain tensioner.

  24. Object Number: 2134128  Size: SH

    Note: The camshaft actuators should not rotate during the removal of installation.

  25. Install the timing chain retention tool EN-48749 (1) to the exhaust side of the timing chain.

  26. Object Number: 1578298  Size: SH
  27. Remove and discard the exhaust camshaft actuator bolt (2).

  28. Object Number: 1578297  Size: SH
  29. Remove and discard the intake camshaft actuator bolt (2).
  30. Remove the intake camshaft actuator (3) from the camshaft while also removing the actuator from the timing chain.

  31. Object Number: 2066509  Size: SH
  32. Mark the cylinder head (1) in relationship to the camshaft actuator notch is on the camshaft (2).

  33. Object Number: 412164  Size: SH
  34. Remove the fixed timing chain guide access plug.

  35. Object Number: 2066512  Size: SH

    Note: The threaded rod from the timing chain retention tool can be used to help feed the rubber band around the chain guides.

  36. Install a rubber band (1) around the top of the upper timing chain guides (2) in order to pull the guides together.

  37. Object Number: 465863  Size: SH
  38. Remove the cylinder head bolts in the sequence shown. Discard the bolts.

  39. Object Number: 412427  Size: SH
  40. Remove the cylinder head.
  41. Remove the cylinder head gasket.
  42. Clean all of the gasket surfaces.
  43. Use the following steps when cleaning the cylinder head and cylinder block surfaces:
  44. • Use a razor blade gasket scraper to clean the cylinder head and cylinder block gasket surfaces. Do not scratch or gouge either surface.

       Note: DO NOT use any other method or technique to clean these gasket surfaces.

    • Use a NEW razor blade on the cylinder head and a NEW blade on the cylinder block.

       Note: Be careful not to gouge or scratch the gasket surfaces. DO NOT gouge or scrape the combustion chamber surfaces. The feel of the gasket surface is important, not the appearance. There will be indentations from the gasket left in the cylinder head after all of the gasket material is removed. These small indentations will be filled in by the NEW gasket.

    • Hold the razor blade as parallel to the gasket surface as possible.
  45. Clean the old sealer/lube and any dirt from around the bolt holes.
  46. Note: DO NOT use a tap to clean the cylinder head bolt holes.

  47. Clean the bolts holes with a nylon bristle brush.
  48. When cleaning the cylinder head bolt holes use suitable commercial spray liquid solvent and compressed air from an extended-tip blow gun in order to reach the bottom of the holes.
  49. If replacing the cylinder head, transfer all parts as necessary.

Installation Procedure


    Object Number: 412427  Size: SH

    Note: DO NOT use any sealing material.

  1. Install the cylinder head gasket.
  2. Install the cylinder head.
  3. Install NEW cylinder head bolts.

  4. Object Number: 412510  Size: SH
  5. Install and tighten the cylinder head bolts in the sequence shown. Tighten the bolts to 30 N·m (22 lb ft) plus an additional 155 degrees using the J 45059 .

  6. Object Number: 412425  Size: SH
  7. Install the NEW front cylinder head bolts and tighten to 35 N·m (26 lb ft).

  8. Object Number: 2066509  Size: SH
  9. Ensure the cylinder head (1) and the camshaft (2) are correctly aligned.

  10. Object Number: 2066512  Size: SH
  11. Remove the rubber band (1) from around the top of the upper timing chain guides (2).
  12. Install the fixed guide bolt into the cylinder bolt and tighten to 12 N·m (106 lb in).

  13. Object Number: 412164  Size: SH
  14. 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.
  15. Install the fixed timing chain guide access plug. Tighten the chain guide plug to 90 N·m (59 lb ft).

  16. Object Number: 1578297  Size: SH

    Note: Ensure that the alignment mark made previously on the exhaust camshaft actuator is still aligned properly with the mark on the timing chain.

  17. Install the timing chain onto the intake camshaft actuator.
  18. Align the intake camshaft actuator alignment mark made previously with the timing chain mark and install the actuator onto the camshaft.
  19. Install a NEW intake camshaft actuator bolt (2) until snug.

  20. Object Number: 2066475  Size: SH
  21. Remove the timing chain retention tool EN-48749 (1) from the intake side of the timing chain.

  22. Object Number: 1578298  Size: SH

    Note: Ensure that the alignment mark made previously on the intake camshaft actuator is still aligned properly with the mark on the timing chain.

  23. Install the timing chain onto the exhaust camshaft actuator.
  24. Align the exhaust camshaft actuator alignment mark made previously with the timing chain mark and install the actuator onto the camshaft.
  25. Install a NEW exhaust camshaft actuator bolt (2) until snug.

  26. Object Number: 2066482  Size: SH
  27. Remove the timing chain retention tool EN-48749 (1) from the exhaust side of the timing chain.
  28. Reset and install the timing chain tensioner. Refer to Timing Chain Tensioner Replacement.

  29. Object Number: 2066456  Size: SH
  30. Install the EN-48953 (1) to the actuators.
  31. Install the camshaft actuator locking tool bolts and tighten to 10 N·m (89 lb in).
  32. Release the tensioner by applying a counterclockwise torque on the harmonic balancer bolt and tighten the bolt to 45 N·m (33 lb ft).
  33. Tighten the NEW camshaft actuator bolt to 85 N·m (63 lb ft), plus an additional 30 degrees using the J 45059 .
  34. Remove the camshaft actuator locking tool, EN-48953 .

  35. Object Number: 1578296  Size: SH
  36. Install the upper timing chain guide bolts and guide. Tighten the bolts to 10 N·m (89 lb in).
  37. Install the camshaft cover. Refer to Camshaft Cover Replacement.

  38. Object Number: 1656126  Size: SH
  39. Connect all electrical connectors as necessary.
  40. Install the radiator inlet hose to the cylinder head.
  41. Position the radiator inlet hose clamp using the J 38185 .
  42. Install the radiator surge tank air bleed hose to the cylinder head.
  43. Position the radiator surge tank air bleed hose clamp.
  44. Install the exhaust manifold. Refer to Exhaust Manifold Replacement.
  45. Install the intake manifold. Refer to Intake Manifold Replacement.
  46. Fill the cooling system. Refer to Cooling System Draining and Filling.