Tools Required

1. Remove both cylinder heads. Refer to Cylinder Head Replacement - Left Side and Cylinder Head Replacement - Right Side .
2. Remove the valve lifters. Refer to Valve Lifter Replacement .
3. Remove the charged air cooler. Refer to Charged Air Cooler Replacement .
4. Remove the cooling layer. Refer to Cooling Layer Removal in Engine Cooling.
5. Remove the starter. Refer to Starter Motor Replacement in Engine Electrical.



6. Install the J 44643 in the starter opening. Ensure the J 44643 is flush to the flywheel opening.

The J 44643 will be used to remove the crankshaft balancer bolt and the camshaft drive gear bolt.

7. Remove the engine front cover. Refer to Engine Front Cover Replacement .



8. Remove the oil pump driven gear nut.
9. Remove the oil pump driven gear.




Important: The crankshaft reluctor and the oil pump drive gear are timed together at the factory. Do not remove the crankshaft reluctor from the oil pump drive gear.

10. Remove the oil pump drive gear and crankshaft reluctor assembly.

•	Do not remove the crankshaft reluctor bolts.

•	Do not damage the reluctor teeth.




11. Using the J 26900-12  (1) and the J 26900-13  (2), measure the camshaft end play.

•	The production value is 0.050-0.114 mm (0.002-0.0045 in) and service limit is 0.20 mm (0.008 in).

•	Replace the camshaft gear or the camshaft thrust plate if measured value exceeds service limit.




12. Remove the camshaft reluctor screws.
13. Remove the camshaft reluctor.



14. In order to loosen the camshaft gear bolt use theJ 44643 in the starter motor opening in order to hold the engine from turning.
15. Loosen the camshaft gear bolt and leave the bolt finger tight.
16. Remove the camshaft thrust plate bolts through the holes in the camshaft gear.



17. Remove the camshaft with the camshaft gear attached.



18. Remove the camshaft gear bolt.
19. Remove the camshaft gear.
20. Remove the camshaft thrust plate.
21. Clean and inspect the camshaft and the bearings. Refer to Camshaft and Bearings Cleaning and Inspection .

If the camshaft bearings are worn or damaged the engine will require removal in order to replace the camshaft bearings. Refer to Engine Replacement .

1. Install the camshaft thrust plate to the camshaft.
2. Install the camshaft driven gear.
3. Install the camshaft driven gear bolt.

Leave the bolt finger tight.




4. Install the camshaft and gear assembly into the cylinder block, aligning the camshaft gear to the crankshaft gear as shown.



5. Apply threadlocker GM P/N 12345493 (Canadian P/N 109534887) or equivalent to the threads of the camshaft thrust plate bolts.

Notice: Refer to Air Brake System Schematics in the Preface section.

6. Install the camshaft thrust plate bolts.

Tighten
Tighten the camshaft thrust plate bolts to 26 N·m (19 lb ft).




7. Install the camshaft reluctor to the camshaft gear.
8. Install the camshaft reluctor bolts.

Tighten
Tighten in a cross-bolt pattern the camshaft reluctor bolts to 9 N·m (80 lb in).




9. Reinstall the J 44643 in the starter opening. if removed.
10. Install the camshaft gear bolt.

Tighten
Tighten the camshaft gear bolt to 234 N·m (173 lb ft).




11. Using the J 26900-12  (1) and the J 26900-13  (2) measure the camshaft end play.

•	The production value is 0.050-0.114 mm (0.002-0.0045 in) and service limit is 0.20 mm (0.008 in).

•	Replace the camshaft gear or the camshaft thrust plate if measured value exceeds the service limit.





Important: Do not damage the teeth on the crankshaft reluctor assembly.

12. Install the oil pump drive gear and reluctor assembly to the crankshaft.



13. Install the oil pump driven gear.
14. Install the oil pump driven gear nut.

Tighten
Tighten the oil pump driven gear nut to 100 N·m (74 lb ft).

15. Install the engine front cover. Refer to Engine Front Cover Replacement .
16. Install the cooling layer. Refer to Cooling Layer Installation in Engine Cooling.
17. Install the charged air cooler. Refer to Charged Air Cooler Replacement .
18. Install the valve lifters. Refer to Valve Lifter Replacement .
19. Install both cylinder heads. Refer to Cylinder Head Replacement - Left Side and Cylinder Head Replacement - Right Side .