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 left camshaft cover. Refer to Camshaft Cover Replacement - Left Side.
  3. Remove the left intake and exhaust camshaft position sensors. Refer to Camshaft Position Sensor Replacement - Bank 2 (Left Side) Intake and Camshaft Position Sensor Replacement - Bank 2 (Left Side) Exhaust.
  4. Remove the left intake and exhaust camshaft position actuator solenoid. Refer to Camshaft Position Actuator Solenoid Valve Solenoid Replacement - Bank 2 (Left Side) Intake and Camshaft Position Actuator Solenoid Valve Solenoid Replacement - Bank 2 (Left Side) Exhaust.
  5. Note: 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: 1306391  Size: SH

    Note: 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 on one of the timing chain links (2) and the adjacent tooth on the exhaust camshaft position actuator (1).
  9. Use a paint stick to create an alignment mark on one of the timing chain links (3) and the adjacent tooth on the intake camshaft position actuator (4).
  10. Caution: Refer to Torque Reaction Against Timing Drive Chain Caution 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: 1858601  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 bottom line that is scribed in the body of the tool (2) is adjacent to the top surface of the cylinder head (1). This is the approximate installed position.

  15. Object Number: 1858602  Size: SH

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

  16. Ensure that the feet (4) on the legs of the tool are facing the front of the engine.
  17. Partially expand the legs (1, 3) of the EN-48313 by turning the T-shaped handle clockwise.
  18. Insert the leg of the tool (1) behind the timing chain guide (2).
  19. Continue expanding the EN-48313 until the legs (1, 3) contact the timing chain. Do not tighten at this time.

  20. Object Number: 1858603  Size: SH

    Note: Ensure that the foot (1) of the EN-48313 is engaged into one of the link pockets to prevent tool slippage during tightening of the EN-48313 .

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

  23. 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.

  24. Object Number: 1858605  Size: SH
  25. The EN-48313 is now properly installed to hold the timing chain in position.
  26. Caution: Refer to Torque Reaction Against Timing Drive Chain Caution in the Preface section.


    Object Number: 1858699  Size: SH
  27. 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.
  28. Remove the left exhaust camshaft position actuator bolt.
  29. Remove the left exhaust camshaft position actuator. When removing the actuator, place the chain on the engine cover side of the actuators.
  30. 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.
  31. 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 circle marking (3).
  4. The marking is for alignment to the highlighted timing chain link on the left side of the engine.


    Object Number: 1306391  Size: SH

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

  5. Align the exhaust camshaft actuator alignment mark (1) to the timing chain alignment mark (2) made during disassembly.
  6. Ensure that the intake camshaft actuator alignment mark (4) and the timing chain alignment mark (3) are also aligned.
  7. Position the exhaust camshaft actuator to the camshaft and install the actuator bolt hand tight.
  8. Remove the EN-48313 .
  9. Caution: Refer to Fastener Caution in the Preface section.


    Object Number: 1858699  Size: SH
  10. Tighten the exhaust camshaft position actuator bolt to 58 N·m (43 lb ft).
  11. Install the left intake and exhaust camshaft position actuator solenoids. Refer to Camshaft Position Actuator Solenoid Valve Solenoid Replacement - Bank 2 (Left Side) Intake and Camshaft Position Actuator Solenoid Valve Solenoid Replacement - Bank 2 (Left Side) Exhaust.
  12. Install the left intake and exhaust camshaft position sensors. Refer to Camshaft Position Sensor Replacement - Bank 2 (Left Side) Intake and Camshaft Position Sensor Replacement - Bank 2 (Left Side) Exhaust.
  13. Install the left camshaft cover. Refer to Camshaft Cover Replacement - Left Side.
  14. Install the lower intake manifold. Refer to Lower Intake Manifold Replacement.