GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

    Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  1. Disconnect the negative battery cable.
  2. Remove the timing chain housing. Refer to Timing Chain Housing Replacement .
  3. Remove the spark plugs in order to make rotating the crankshaft to line up the timing marks easier.

  4. Object Number: 466546  Size: SH

    Important: The timing marks must be correctly aligned before disassembly.

  5. Rotate the crankshaft so that the following conditions are met:
  6. • The number 1 (frontmost) cylinder is at the top dead center (TDC) position on the compression stroke.
    • The keyway on the crankshaft (5) aligns with the mark on the engine block (4).
    • The arrow (3) on the idler sprocket is pointing upward.
    • The guide pins (1) on the camshaft sprockets line up with the notches (6) on the cylinder head.

    Object Number: 466579  Size: SH

    Important: Do not turn the crankshaft or camshaft once the tensioner is removed.

  7. Relieve the tension on the camshaft timing chain by turning the intake camshaft slightly counterclockwise.
  8. Remove the nut and 2 bolts (1, 2).
  9. Remove the camshaft timing chain tensioner and the gasket.

Installation Procedure

  1. Inspect the camshaft timing chain tensioner for wear, damage and correct operation. Replace as necessary.
  2. Inspect the timing chain tensioner gasket and replace as necessary.

  3. Object Number: 464756  Size: SH
  4. Compress the camshaft tensioner plunger into the body. Insert a retainer (a paper clip or similar tool) through the hole in the body in order to hold the plunger in place.

  5. Object Number: 466579  Size: SH

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  6. Install the gasket and the camshaft timing chain tensioner.
  7. Tighten

        • Tighten the bolts (1) to 11 N·m (97 lb in).
        • Tighten the nut (2) to 45 N·m (33 lb ft).
  8. Remove the retainer from the tensioner.

  9. Object Number: 466546  Size: SH
  10. Turn the crankshaft 2 revolutions realigning the keyway on the crankshaft (5) with the timing mark on the engine block (4).
  11. Ensure that the guide pins on the camshafts (1) are in line with the notches on the cylinder head (6).
  12. Apply engine oil to the following:
  13. • The timing chains
    • The tensioner
    • The guides
    • The sprockets
  14. Install the spark plugs.
  15. Tighten
    Tighten the spark plugs to 25 N·m (18 lb ft).

  16. Install the timing chain housing. Refer to Timing Chain Housing Replacement .
  17. Connect the negative battery cable.