Notice: Perform TDC Offset Recovery procedure if the timing chain, timing gears, engine front cover, crankshaft position sensor, crankshaft or other components affecting the timing are replaced.

Caution: Before servicing any electrical component, the ignition and start switch must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.

1. Disconnect the battery negative cable from the battery. Refer to Battery Cable Replacement
2. Drain the cooling system. Refer to Draining and Filling Cooling System .
3. Remove the front grille and parking lamp assembly from the vehicle.
4. Remove the air conditioning condenser from the vehicle.

•	For commercial applications, refer to Condenser Replacement (Commercial) in HVAC.

•	For motorhome applications, refer to Condenser Replacement (Motorhome) in HVAC.

5. Remove the radiator from the vehicle. Refer to Radiator Replacement (Diesel) .
6. Remove the oil pump drive from the engine block. Refer to Oil Pump Drive Replacement .
7. Remove the valve lifters from the engine block. Refer to Valve Lifter Replacement .



8. Remove the timing chain from the engine block. Refer to Timing Chain and Sprocket Replacement .



9. Remove the camshaft thrust plate retaining bolts and the camshaft thrust plate from the engine block.



10. Remove the camshaft thrust plate spacer from the engine block.

Important: When removing the camshaft from the engine block, use caution as not to damage the camshaft bearing.




11. Remove the camshaft assembly from the engine block.

Important: When a new camshaft is being installed, new valve lifters, engine oil and oil filter must be replacement at the same time.

Important: When installing the camshaft assembly into the engine block, use caution as not to damage the camshaft bearing during installation.

1. Install the camshaft sprocket spacer, with the ID chamfer facing the camshaft.



2. Install the camshaft.

2.1.	Coat the camshaft lobes with camshaft and valve Prelube GM P/N 1052365.

2.2.	Lubricate the camshaft bearing journals with clean engine oil.

2.3.	Carefully insert the camshaft into the block, in order to avoid damage to the camshaft bearings.




3. Install the camshaft thrust plate to the engine block.

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.

4. Install the thrust plate retaining bolts.

Tighten
Tighten the bolts to 23 N·m (17 lb ft).




5. Install the timing chain and sprockets to the camshaft. Refer to Timing Chain and Sprocket Replacement .
6. Install the cylinder heads to the engine block. Refer to Cylinder Head Replacement
7. Install the valve lifters in the engine block. Refer to Valve Lifter Replacement .
8. Install the oil pump drive to the engine block. Refer to Oil Pump Drive Replacement .
9. Install the radiator to the vehicle. Refer to Radiator Replacement (Diesel) .
10. Install the air conditioning condenser to the vehicle.

•	For commercial applications, refer to Condenser Replacement (Commercial) in HVAC.

•	For motorhome applications, refer to Condenser Replacement (Motorhome) in HVAC.

11. Install the front grille and parking lamp assembly to the vehicle.
12. Refill the cooling system. Refer to Draining and Filling Cooling System .
13. Connect the battery negative cable to the battery. Refer to Battery Cable Replacement .
14. Perform the TDC offset adjustment procedure.

•	For the L-65, refer to TDC Offset Adjustment

•	For the L-57 (EFI), refer to TDC Offset Adjustment (MFI)

•	For the L-57 (MFI), refer to TDC Offset Adjustment (EFI)