Tools Required

J 41088 Balance Shaft Holder

Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

1. Disconnect the negative battery cable.
2. Remove the engine oil pan. Refer to Oil Pan Replacement .



3. Remove the balance shaft chain cover nut and bolt.
4. Remove the balance shaft chain cover.



5. Loosen but do remove the balance shaft chain tensioner.
6. Remove the oil pump cover.



7. Remove the oil pump assembly.
8. Rotate the engine crankshaft until the number one piston is at TDC.
9. Use J 41088 to prevent the balance shafts from turning while loosening the bolt.

Important: The balance shaft driven sprocket bolt is left-hand threaded and must be loosened by rotating it in a clockwise direction.

10. Remove the balance shaft driven sprocket bolt.

Important: Mark the surface of the driven sprocket if it is going to be reused. This will insure that the chain continues to ride on the same tooth surface. If a new driven sprocket will be installed, either surface can be placed against the shaft.

11. Remove the driven sprocket from the shaft.
12. Remove the balance shaft assembly fasteners and remove the assembly to the bench.
13. Check the balance shaft end play prior to disassembling the balance shaft housing.

•	Set up the indicator to read off the back of the shafts.

•	Press against the one shaft and note the movement.

•	Repeat the above step on the other shaft.

•	Compare against specifications.

•	If out of specs, check the thrust plate for wear. Replace if necessary. If the end play is out of specs and the thrust plate is not worn, replace the balance shafts.

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.

1. Install the balance shaft assembly to the engine block. Use GM P/N 123454493 on the housing to block bolts.

Tighten
Tighten the balance shaft assembly to the engine block bolts to specifications.

2. Install the balance shaft driven sprocket.

Tighten
Tighten the bolt to 30 N·m (22 lb ft). Use J 41088 to hold balance shafts in the correct timed location.




3. Install the balance shaft chain tensioner and torque to specifications.



4. Install the balance shaft chain cover.

Tighten
Tighten the nut and the bolt to 13 N·m (115 lb in).

5. Install the oil pan gasket and the oil pan. Refer to Oil Pan Replacement .
6. Connect the negative battery cable.