Connecting Rod Bearing Selection

Tools Required 

J 36660-A  Torque Angle Meter

The connecting rod bearings are of the precision insert type. The connecting rod bearings are available in standard and various undersizes.

Important:  If crankshaft bearing failure is due to other than normal wear, investigate the cause. Inspect the crankshaft or connecting rod bearing bores.

1. Inspect the connecting rod bearing bores using the following procedure:
   1. 1.1. Tighten the bearing cap to specification.
   2. 1.2. Measure the bearing bore for taper and out-of-round.
   3. 1.3. No taper or out-of-round should exist.
   Fig 1: Inspecting Connecting Rod Bearing Bores

   Courtesy of GENERAL MOTORS CORP.

   Important:  The crankshaft and the lower crankcase assembly must be installed and properly torqued before measuring the connecting rod clearances.

2. Starting with the number one connecting rod, remove the connecting rod cap bolts.
   Fig 2: Removing Connecting Rod Cap Bolts

   Courtesy of GENERAL MOTORS CORP.
3. Remove the connecting rod cap by partially reinserting the connecting rod cap bolts into the connecting rod cap and wiggle the connecting rod cap left and right.
   Fig 3: Removing Connecting Rod Cap

   Courtesy of GENERAL MOTORS CORP.
4. Lay a piece of gaging plastic across the crankshaft number one connecting rod journal.
   Fig 4: Laying Gaging Plastic Across Crankshaft Connecting Rod Journal

   Courtesy of GENERAL MOTORS CORP.

   Important:  Do not turn the crankshaft while measuring the bearing clearance.

5. Carefully place the connecting rod cap onto the connecting rod.
   NOTE: Refer to FASTENER NOTICE .
6. Install the 2 connecting rod bearing cap bolts.

   Tighten 

   Tighten the connecting rod bearing cap bolts to 30 N.m (22 Ib. ft), then rotate 90 degrees using the J 36660-A  .

7. After reaching the proper torque, remove the 2 crankshaft connecting rod bearing cap bolts.
8. Carefully remove the connecting rod cap from the connecting rod.
9. Measure the gaging plastic at its widest point.
   • Standard Oil Clearance:

     0.028-0.052 mm (0.0011-0.0020 in)

   • Maximum Oil Clearance:

     0.08 mm (0.0031 in)

   Fig 5: Measuring Gaging Plastic

   Courtesy of GENERAL MOTORS CORP.
10. If using a standard bearing, replace it with one having the same number. There are 3 sizes of standard bearings.
    Fig 6: Replacing Standard Bearing

    Courtesy of GENERAL MOTORS CORP.