GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 26999 Compression Gauge
    • J 26999-10 Compression Gauge Adapter
    •  J 26999-30 Compression Gauge Adapter
    •  J 38606 Valve Spring Compressor

Removal Procedure


    Object Number: 66613  Size: SH
  1. Disconnect both the battery negative cables from the batteries. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  2. Remove the valve rocker arm covers. Refer to Valve Rocker Arm Cover Replacement - Left Side or Valve Rocker Arm Cover Replacement - Right Side .
  3. Remove the valve rocker arm, shaft, and pushrod from the engine block. Refer to Valve Rocker Arm, Shaft, and Push Rod Replacement .
  4. Remove the glow plug from the cylinder being serviced.
  5. • For the left cylinder head, refer to Glow Plug Replacement - Bank 1 in Engine Controls-6.5L (L65).
    • For the right cylinder head, refer to Glow Plug Replacement - Bank 2 in Engine Controls-6.5L (L65).
  6. Modify the J 26999-10 and the J 26999-30 . A valve core is used to prevent the lost of engine compression when using for compression test.
  7. 5.1. Remove the valve core from theJ 26999-10 or the J 26999-30 .
    5.2. Remove the quick connect fitting from the J 26999 .
    5.3. Adapt the quick connect fitting in order to use for shop air.
  8. Rotate the engine until the piston in the cylinder being serviced is at the bottom of the piston stroke. This is to ensure that the engine does not rotate when compressed air is applied to the cylinder being serviced.
  9. Use the J 26999-10 left side of the engine and J 26999-30 for the right side of the engine when applying the compressed air to the cylinder being serviced.
  10. Important: Make sure that the compressed air is not released, until the repair is completed.

  11. Apply compressed air into the cylinder being serviced.
  12. Tap lightly on the valve spring cap or rotator to loosen the valve keys.
  13. Caution: Compressed valve springs have high tension against the valve spring compressor. Valve springs that are not properly compressed by or released from the valve spring compressor can be ejected from the valve spring compressor with intense force. Use care when compressing or releasing the valve spring with the valve spring compressor and when removing or installing the valve stem keys. Failing to use care may cause personal injury.

    Notice: Completely engage the J 38606 jaws on the valve spring. The J 38606 may slip off and scratch the valve spring. Replace the valve spring if the valve spring becomes scratch.

  14. Use the J 38606 in order to compress the valve spring.
  15. Compress the valve spring.

  16. Object Number: 526635  Size: SH
  17. Remove the valve keys from the retainers from the cylinder being serviced.
  18. Carefully release the valve spring tension and remove the J 38606 .
  19. Remove the valve stem oil seals from the valve guides.

Installation Procedure

Important: The air pressure should remain applied to the cylinder being serviced until after the repair has been completed.


    Object Number: 526635  Size: SH
  1. Apply a small amount of clean engine oil to the valve stem and to the new valve stem oil seal.
  2. Install the valve stem oil seal to the valve stem.
  3. Install the valve spring, cap, rotator and shield.
  4. Use the J 38606 to compress the valve spring.

  5. Object Number: 66613  Size: SH

    Caution: Compressed valve springs have high tension against the valve spring compressor. Valve springs that are not properly compressed by or released from the valve spring compressor can be ejected from the valve spring compressor with intense force. Use care when compressing or releasing the valve spring with the valve spring compressor and when removing or installing the valve stem keys. Failing to use care may cause personal injury.

    Notice: Completely engage the J 38606 jaws on the valve spring. The J 38606 may slip off and scratch the valve spring. Replace the valve spring if the valve spring becomes scratch.

  6. Install valve spring assembly to the cylinder head.
  7. Install the valve keys in the retainer.
  8. • Apply a small amount of grease on the valve stem end. This will help to hold the valve keys in place.
    • Carefully release the valve spring pressure. Make sure the valve key are properly seated in the cap.
    • Remove theJ 38606 from the valve spring.
  9. Slowly release the compressed air from the cylinder being serviced.
  10. Remove the J 26999-10 when working on the left side of the engine and J 26999-30 for the right side of the engine.
  11. Install the glow plug to the cylinder head.
  12. • For the left cylinder head, refer to Glow Plug Replacement - Bank 1 in Engine Controls-6.5L (L65).
    • For the right cylinder head, refer to Glow Plug Replacement - Bank 2 in Engine Controls-6.5L (L65).

    Important: All the valve train components must be reassembled in the exact order and position from which they were removed.

  13. Install the valve rocker arm and pushrod to the cylinder head. Refer to Valve Rocker Arm, Shaft, and Push Rod Replacement .
  14. Install the valve rocker arm covers. Refer to Valve Rocker Arm Cover Replacement - Left Side or Valve Rocker Arm Cover Replacement - Right Side .
  15. Connect both the battery negative cables to the batteries. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.