GM Service Manual Online
For 1990-2009 cars only

The crankshaft main bearing caps are numbered 1, 2, 3 from the front of the engine. The rear bearing cap is not numbered and contains the thrust bearings. The number 2 and 3 main bearing shells do not have oil grooves on the cap sides.

There is a 0 or 1 stamped on the cylinder block oil pan mating flange near the end of each main bearing cap. This is the determining number. The determining number corresponds to each crankshaft main bearing size and color that will be installed.

    • The cylinder block main bearing journal diameter for a determining number of 0 is 72-72.0065 mm (2.83 in).
    • The cylinder block main bearing journal diameter for a determining number of 1 is 72.0065-72.013 mm (2.83-2.84 in).

The crankshaft main bearing size, selective fits, chart shows the color of bearing that must be used for the respective determining number stamp.

To select the correct main bearing size, determine the number stamp, determining number, for the respective main bearing journal on the oil pan mating flange (0 or 1) by doing the following:

  1. Measure the crankshaft main bearing journal. Refer to the crankshaft main bearing size selective fits chart.
  2. Select the correct determining number column.
  3. Select the measured main bearing journal diameter range.
  4. Select the block side color.
  5. Select the cap side color.