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Measuring Crankshaft Bearing Clearances - Micrometer Method

WARNING: This page is about a different car, the 2002 GMC Savana and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
  1. Measure the crankshaft journal diameter with a micrometer in several places, approximately 90 degrees apart. Average the measurements.
  2. Determine the taper and out-of-round of the journal. Refer to Engine Mechanical Specifications .
  3. Install the bearings into the engine block or connecting rod assembly.
    Fig 1: Bearings
    G01689665Courtesy of GENERAL MOTORS CORP.
  4. Install the bearing cap bolts and tighten to specifications. Refer to Specifications .
  5. Measure the bearing inside diameter (ID) at two points 90 degrees apart. Average the measurements.
  6. In order to determine the bearing clearance, subtract the average journal diameter from the average bearing inside diameter.
  7. Compare the readings to specifications. Refer to Engine Mechanical Specifications .
  8. Replace bearing halves as required to obtain the proper bearing clearances.
    Fig 2: Bearing Cap Bolts
    G01689666Courtesy of GENERAL MOTORS CORP.