Tools Required

1. Install the balance shaft assembly to the block. Use Loctite 272 GM P/N 12345493 on the housing assembly to the block bolts.
2. If the balance shaft housing was dissassembled, loosely assemble the housing assembly to the block.



3. Tighten the housing fasteners in sequence.

Tighten

•	Tighten fasteners 1, 2, 4, 5, 6 and 7 to 15 N·m (11 lb ft) + 40 degrees.

•	Tighten fasteners 3 and 8 to 10 N·m (89 lb in) + 40 degrees.

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. Tighten the housing assembly to block bolts in sequence.

Tighten

•	Tighten bolts 1,2 and 4 to 25 N·m (18 lb ft) + 70 degrees.

•	Tighten bolt 3 to 40 N·m (30 lb in) + 60 degrees.

•	Tighten bolt 5 to 53 N·m (39 lb ft).

5. Ensure that the balance shafts spin freely.
6. If the balance shaft housing was dissassembled, install the oil pump pick-up screen into the housing. Lightly tap it into place with a plastic hammer.

Important: If the balance shafts are not properly timed to the engine, the engine may vibrate or make noise.

7. Use the following steps to time the balance shaft to the engine:

7.1.	Place the number one piston at TDC.

7.2.	Rotate the crankshaft 90 degrees.

7.3.	Install the J 38122-A on to the balance shaft assembly in order to ensure that the shafts do not rotate while the driven sprocket bolt is tightened.

Important: The surface that was marked during disassembly of the driven sprocket must show if it is going to be reused. This will insure that the chain continues to ride on the same surface. If a new driven sprocket will be installed, either surface can be placed against the shaft.

8. Install the driven sprocket to the shaft.




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

9. Install the balance shaft driven sprocket bolt, finger tighten.



10. Install the balance shaft chain guide.
11. Press the chain guide tightly against the chain.
12. Tighten the chain tensioner bolt.

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

13. Tighten the balance shaft driven sprocket bolt.

Tighten
Tighten the bolt to 40 N·m (30 lb ft) and rotate the bolt 45 degrees.

14. Remove the J 38122-A from the balance shaft housing assembly.
15. Loosen the balance shaft chain guide bolt.

Important: A brass feeler gauge needs to be used to ensure correct measurements are obtained. If a steel gauge is used, it will not bend to conform to the guide and will cause incorrect measurements.

16. Use the following procedure to adjust the balance shaft drive chain tension:

16.1.

Inserting a 1 mm (0.040 in) brass feeler gauge between the chain guide and the chain.

16.2.

Press the guide against the chain. Use about three pounds of force.

16.3.

Tighten the chain fastener bolt.

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




17. Install the balance shaft chain cover.
18. Install the balance shaft chain cover nut and bolt.

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