GM Service Manual Online
For 1990-2009 cars only

    Object Number: 373797  Size: SH
  1. Gradually loosen and remove the main bearing cap bolts in the sequence shown.
  2. Remove the bearing caps.
  3. Carefully remove the crankshaft from the cylinder block.
  4. Important: Use caution when removing the crankshaft and avoid damage to the crankshaft journals.

  5. Remove the bearing inserts from the block.
  6. Clean the oil, sludge, and carbon.
  7. Inspect the oil passages for obstructions.
  8. Inspect the keyway.
  9. Inspect the threads.
  10. Inspect the bearing journals and the thrust surfaces for the following conditions:
  11. • Cracks
    • Chips
    • Gouges
    • Roughness
    • Grooves
    • Overheating (discoloration)
  12. Inspect the corresponding bearing inserts for imbedded foreign material. If foreign material exists find the cause and repair it.
  13. Important: Replace the crankshaft if cracks, severe gouges or burned spots are found. Slight roughness may be removed with a fine polishing cloth soaked in clean engine oil. Burrs may be removed with a fine oil stone.

  14. Measure the crankshaft journals. Use a micrometer or dial indicator to measure the taper and runout. Note the result for the later selection of bearing inserts. If not within limits the crankshaft must be replaced.
  15. Note the location of the main bearing high spots. If they are not in line, the crankshaft is bent and must be replaced.