GM Service Manual Online
For 1990-2009 cars only

Special Tools

EN-48313 Timing Chain Retention Tool

Removal Procedure


    Object Number: 1306293  Size: SH
  1. Remove the lower intake manifold. Refer to Lower Intake Manifold Replacement.
  2. Remove the right camshaft cover. Refer to Camshaft Cover Replacement - Right Side.
  3. Remove the right intake and exhaust camshaft position sensors. Refer to Camshaft Position Sensor Replacement - Bank 1 (Right Side) Intake and Camshaft Position Sensor Replacement - Bank 1 (Right Side) Exhaust.
  4. Remove the right intake and exhaust camshaft position actuator solenoids. Refer to Camshaft Position Actuator Solenoid Valve Solenoid Replacement - Bank 1 (Right Side) Intake and Camshaft Position Actuator Solenoid Valve Solenoid Replacement - Bank 1 (Right Side) Exhaust.
  5. Important: Rotate the crankshaft balancer bolt in a clockwise direction ONLY.

  6. Rotate the crankshaft balancer using the balancer bolt until the camshafts are in a neutral (low tension) position. The camshafts will be parallel with the camshaft cover rail (1).

  7. Object Number: 1306457  Size: SH

    Important: Ensure that the camshaft timing chain and the camshaft position actuators are marked for proper assembly.

  8. Use a paint stick to create an alignment mark (17) on one of the timing chain links and the adjacent tooth on the exhaust camshaft position actuator (18).
  9. Use a paint stick to create an alignment mark (16) on one of the timing chain links and the adjacent tooth on the intake camshaft position actuator (15).
  10. Notice: Refer to Torque Reaction Against Timing Drive Chain Notice in the Preface section.

  11. Use an open end wrench on the hex cast into the left intake and exhaust camshafts and rotate the camshafts toward each other in order to create slack in the chain between the actuators.

  12. Object Number: 1858791  Size: SH
  13. Unscrew the EN-48313 so that the legs of the tool are retracted.
  14. Insert the EN-48313 between the camshaft actuators, rearward of the timing chain until the top line that is scribed in the body of the tool (1) is adjacent to the top surface of the cylinder head (2). This is the approximate installed position.

  15. Object Number: 1858794  Size: SH

    Important: The engine front cover is removed for clarity in the following graphics, but NOT required to perform the procedure.

  16. Ensure that the feet (2) on the legs of the tool are facing the front of the engine.
  17. Partially expand the legs (1) of the EN-48313 by turning the T-shaped handle clockwise.
  18. Continue expanding the EN-48313 until the feet (2) contact the timing chain. Do not tighten at this time.

  19. Object Number: 1858603  Size: SH

    Important: 

       • Ensure that the foot (1) of the EN-48313 is engaged into one of the link pockets to prevent chain slippage during tightening of the EN-48313 .
       • Do not allow the body of the EN-48313 to rotate when tightening the T-handle.

  20. Hand tighten the EN-48313 .
  21. Notice: Refer to Torque Reaction Against Timing Drive Chain Notice in the Preface section.

  22. Use an open end wrench on the hex cast into the body of the EN-48313 and hand tighten the T-handle.
  23. Notice: Refer to Torque Reaction Against Timing Drive Chain Notice in the Preface section.

  24. Use an open end wrench on the hex cast into the right intake and exhaust camshafts and rotate the camshafts towards each other in order to create slack in the chain between the actuators.

  25. Object Number: 1858795  Size: SH
  26. The EN-48313 is now properly installed to hold the timing chain in position.
  27. Notice: Refer to Torque Reaction Against Timing Drive Chain Notice in the Preface section.


    Object Number: 1852282  Size: SH
  28. Use an open end wrench on the hex cast into the camshaft in order to prevent engine rotation when loosening the camshaft position actuator bolt.
  29. Remove the right exhaust camshaft position actuator bolt.
  30. Remove the right exhaust camshaft position actuator. When removing the actuator, place the chain on the engine cover side of the actuators.
  31. Rotate the actuator in order to align the opening in the actuator reluctor wheel with the cam sensor boss in the front cover, to allow actuator removal.
  32. If removing both the exhaust and intake camshaft actuators, the timing chain can be draped over the EN-48313 once the actuators have been removed.

Installation Procedure


    Object Number: 1852281  Size: SH
  1. Ensure the proper camshaft position actuator is installed. Observe the body of the camshaft position actuator for the EX marking (1).
  2. The marking is for an exhaust camshaft position actuator,

  3. Ensure the proper timing mark is used. Observe the outer ring of the camshaft position actuator for the triangle marking (2).
  4. The marking is for alignment to the highlighted timing chain link on the right side of the engine,

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

  5. Use an open wrench on the hex cast into the camshaft in order to prevent camshaft rotation when tightening the camshaft position actuator bolt.

  6. Object Number: 1306457  Size: SH

    Important: Ensure that the camshaft timing chain and the camshaft position actuators are marked for proper assembly.

  7. Align the exhaust camshaft actuator alignment mark (18) to the timing chain alignment mark (17) made during disassembly.
  8. Ensure that the intake camshaft actuator alignment mark (15) and the timing chain alignment mark (16) are also aligned.
  9. Position the exhaust camshaft actuator to the camshaft and install the actuator bolt hand tight.
  10. Remove the EN-48313 .
  11. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 1852282  Size: SH
  12. Tighten the right exhaust camshaft position actuator bolt.
  13. Tighten
    Tighten the bolt to 58 N·m (43 lb ft).

  14. Install the right intake and exhaust camshaft position actuator solenoids. Refer to Camshaft Position Actuator Solenoid Valve Solenoid Replacement - Bank 1 (Right Side) Intake and Camshaft Position Actuator Solenoid Valve Solenoid Replacement - Bank 1 (Right Side) Exhaust.
  15. Install the right intake and exhaust camshaft position sensors. Refer to Camshaft Position Sensor Replacement - Bank 1 (Right Side) Intake and Camshaft Position Sensor Replacement - Bank 1 (Right Side) Exhaust.
  16. Install the right camshaft cover. Refer to Camshaft Cover Replacement - Right Side.
  17. Install the lower intake manifold. Refer to Lower Intake Manifold Replacement.