Balance Shaft Housing - Installation

Tools Required: 

• J 41088  Balance Shaft Holder
• J 36660-A  Torque Angle Meter

1. Install the balance shaft assembly to the block.
2. Apply GM P/N United States 12345493, GM P/N Canada 10953488 or the equivalent on the housing assembly to the block bolts.
3. If the balance shaft housing was disassembled, loosely assemble the housing assembly to the block.
4. Tighten the housing fasteners in sequence.
   • Tighten fasteners 1, 2, 4, 5, 6 and 7 to 15 N.m (11 ft lbs) + 40 degrees.
   • Tighten fasteners 3 and 8 to 10 N.m (89 in lbs) + 40 degrees.
     Fig 1: Balance Shaft Housing Fastener Tightening Sequence

     Courtesy of GENERAL MOTORS CORP.
5. Tighten the housing assembly to block bolts in sequence.
   • Tighten bolts 1, 2, and 4 to 25 N.m (18 ft lbs) + 70 degrees.
   • Tighten bolt 3 to 40 N.m (30 in lbs) + 60 degrees.
   • Tighten bolt 5 to 53 N.m (39 ft lbs).
Fig 2: Balance Shaft Housing Assembly-To-Block Bolt Tightening Sequence
Courtesy of GENERAL MOTORS CORP.
6. Ensure that the balance shafts spin freely.
7. If the balance shaft housing was disassembled, install the oil pump pick-up screen into the housing. Lightly tap the oil pump pick-up screen 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.

8. Use the following steps to time the balance shaft to the engine:
   1. 8.1. Place the number one piston at TDC.
   2. 8.2. Rotate the crankshaft 90 degrees.
   3. 8.3. Install the J 41088  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 the drive sprocket 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.

9. Install the driven sprocket to the shaft.
   Fig 3: Installing Balance Shaft Holder

   Courtesy of GENERAL MOTORS CORP.

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

10. Install the balance shaft drive sprocket bolt. Finger tighten the bolt.
Fig 4: Balance Shaft Driven Sprocket
Courtesy of GENERAL MOTORS CORP.
11. Install the balance shaft chain guide.
12. Press the chain guide tightly against the chain.
13. Tighten the chain tensioner bolt. Tighten the bolt to 13 N.m (115 in lbs).
14. Tighten the balance shaft driven sprocket bolt. Tighten the bolt to 40 N.m (30 ft lbs) and rotate the bolt 45 degrees.
15. Remove the J 41088  from the balance shaft housing assembly.
16. Loosen the balance shaft chain guide bolt.
    Fig 5: Balance Shaft Chain Guide

    Courtesy of GENERAL MOTORS CORP.

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

17. Use the following procedure to adjust the balance shaft drive chain tension:
    1. 17.1. Inserting a 1 mm (0.040 in) brass feeler gauge between the chain guide and the chain.
    2. 17.2. Press the guide against the chain. Use about three pounds of force.
    3. 17.3. Tighten the chain fastener bolt. Tighten the bolt to 13 N.m (115 in lbs).
18. Install the balance shaft chain cover.
19. Install the balance shaft chain cover nut and bolt. Tighten the nut and bolt to 13 N.m (115 in lbs).
Fig 6: Balance Shaft Chain Cover
Courtesy of GENERAL MOTORS CORP.