Tools Required

J 36660-A  Torque Angle Meter. See Special Tools .

1. The crankshaft bearings are of the precision insert type. The crankshaft bearings are available in standard and various undersizes.
Fig 1: Crankshaft
Courtesy of GENERAL MOTORS CORP.
IMPORTANT: If crankshaft bearing failure is due to other than normal wear, investigate the cause. Inspect the crankshaft bearing bores.
2. Inspect the crankshaft main bearing bores using the following procedure:
   1. Tighten the bearing cap to specification.
   2. Measure the bearing bore for taper and out-of-round.
   3. No taper or out-of-round should exist.
Fig 2: Installing Crankshaft Main Bearing Inserts
Courtesy of GENERAL MOTORS CORP.
3. Install the original crankshaft main bearing inserts on to the cylinder block and the lower crankcase assembly.
4. Carefully place the crankshaft on to the bearing inserts in the cylinder block.
5. Lay a piece of gaging plastic across each crankshaft main journal.
IMPORTANT: Do not turn the crankshaft while measuring the bearing clearance.
6. Carefully place the lower crankcase assembly on to the cylinder block.
Fig 3: Bearing Cap Bolts
Courtesy of GENERAL MOTORS CORP.
NOTE: Refer to Fastener Notice in Cautions and Notices.
7. Install the ten main bearing cap bolts.

   Tighten:  Tighten the crankshaft main bearing cap bolts in the sequence shown, use three progressive steps to obtain 44 N.m (32 lb ft), then use a J 36660-A  and tighten the main bearing cap bolts an additional 90 degrees. See Special Tools .

8. After reaching the proper torque, remove the ten crankshaft main bearing cap bolts.
9. Carefully remove the lower crankcase assembly from the cylinder block.
Fig 4: Measuring Gaging Plastic
Courtesy of GENERAL MOTORS CORP.
10. Measure the gaging plastic at its widest point.

    • Standard Oil Clearance:  0.016-0.032 mm (0.0006-0.0013 in)

    • Maximum Oil Clearance:  0.080 mm (0.0031 in)

Fig 5: Cylinder Block Numbers
Courtesy of GENERAL MOTORS CORP.
11. If using a standard bearing, replace it with one having the same number. If the number of the bearing cannot be determined, select the correct bearing by determining the numbers imprinted on the cylinder block (1-5).
Fig 6: Crankshaft Numbers
Courtesy of GENERAL MOTORS CORP.
12. If using a standard bearing, replace it with one having the same number. If the number of the bearing cannot be determined, select the correct bearing by determining the numbers imprinted on the crankshaft (1-5). Refer to the Main Bearing Selection Formula, the Main Bearing Selection Chart and the Crankshaft Main Bearing Table in Engine Mechanical Specifications .