GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 7872 Magnetic Base Dial Indicator Set


    Object Number: 156153  Size: SH

    Important: Use care when handling the crankshaft. Avoid damage to the bearing surfaces or the lobes of the crankshaft position reluctor ring. Damage to the teeth of the crankshaft position reluctor ring may affect on-board diagnostic (OBD) II system performance.

  1. Clean the crankshaft with solvent.
  2. Thoroughly clean all oil passages and inspect for restrictions or burrs.
  3. Caution: Refer to Safety Glasses Caution in the Preface section.

  4. Dry the crankshaft with compressed air.
  5. Important: Reluctor ring teeth should not have imperfections on the rising or falling edges.

    Imperfections of the reluctor ring teeth may effect OBD II system performance.

  6. Perform a visual inspection of the crankshaft for damage.

  7. Object Number: 1779857  Size: SH
  8. The crankshaft position reluctor ring may be replaced if damaged.
  9. Tighten
    Tighten the crankshaft position reluctor ring bolts to 15 N·m (11 lb ft).


    Object Number: 156170  Size: SH
  10. Inspect the crankshaft journals for wear (1). The journals should be smooth, with no signs of scoring, wear, or damage.
  11. Inspect the crankshaft journals for grooves or scoring (2).
  12. Inspect the crankshaft journals for scratches or wear (3).
  13. Inspect the crankshaft journals for pitting or imbedded bearing material (4).

  14. Object Number: 35207  Size: SH
  15. Measure the crankshaft journals for out-of-round.
  16. Measure the crankshaft journals for taper.

  17. Object Number: 35210  Size: SH
  18. Measure the crankshaft runout.
  19. Using wooden V-blocks, support the crankshaft on the front and rear journals.

  20. Use the J 7872 in order to measure the crankshaft runout at the front and rear intermediate journals.
  21. Use the J 7872 in order to measure the runout of the crankshaft rear flange.
  22. Replace the crankshaft if the measurements are not within specifications.

  23. Object Number: 52051  Size: SH
  24. Inspect crankshaft bearings for craters or pockets. Flattened sections on the bearing halves also indicate fatigue.

  25. Object Number: 52053  Size: SH
  26. Inspect the crankshaft bearings for excessive scoring or discoloration.
  27. Inspect the crankshaft bearings for dirt or debris imbedded into the bearing material.

  28. Object Number: 52056  Size: SH
  29. Inspect the crankshaft bearings for improper seating indicated by bright, polished sections of the bearing.
  30. If the lower half of the bearing is worn or damaged, both upper and lower halves should be replaced.

    Generally, if the lower half is suitable for use, the upper half should also be suitable for use.

Special Tools

EN-7872 Magnetic Base Dial Indicator Set

For equivalent regional tools, refer to Special Tools.


    Object Number: 2146332  Size: SH

    Note: Use care when handling the crankshaft. Avoid damage to the bearing surfaces or the lobes of the crankshaft position reluctor ring. Damage to the teeth of the crankshaft position reluctor ring may affect on-board diagnostic (OBD) II system performance.

  1. Clean the crankshaft (1) with solvent.
  2. Thoroughly clean all oil passages and inspect for restrictions or burrs.
  3. Warning: Refer to Safety Glasses Warning in the Preface section.

  4. Dry the crankshaft with compressed air.
  5. Note: Reluctor ring teeth should not have imperfections on the rising or falling edges.

    Imperfections of the reluctor ring teeth may effect OBD II system performance.

  6. Perform a visual inspection of the crankshaft for damage.

  7. Object Number: 2146333  Size: SH
  8. The crankshaft position reluctor ring (1) may be replaced if damaged. Tighten the crankshaft position reluctor ring bolts to 15 N·m (11 lb ft).

  9. Object Number: 156170  Size: SH
  10. Inspect the crankshaft journals for wear (1). The journals should be smooth, with no signs of scoring, wear, or damage.
  11. Inspect the crankshaft journals for grooves or scoring (2).
  12. Inspect the crankshaft journals for scratches or wear (3).
  13. Inspect the crankshaft journals for pitting or imbedded bearing material (4).

  14. Object Number: 2146334  Size: SH
  15. Measure the crankshaft journals (1) for out-of-round.
  16. Measure the crankshaft journals for taper.

  17. Object Number: 2146335  Size: SH
  18. Measure the crankshaft runout.
  19. Using wooden V-blocks, support the crankshaft on the front and rear journals.

  20. Use the EN-7872 indicator  (1) in order to measure the crankshaft runout at the front and rear intermediate journals.
  21. Use the EN-7872 indicator in order to measure the runout of the crankshaft rear flange.
  22. Replace the crankshaft if the measurements are not within specifications.

  23. Object Number: 2146336  Size: SH
  24. Inspect crankshaft bearings for craters or pockets (1). Flattened sections on the bearing halves also indicate fatigue.
  25. Inspect the crankshaft bearings for excessive scoring or discoloration (2).
  26. Inspect the crankshaft bearings for dirt or debris imbedded into the bearing material.
  27. Inspect the crankshaft bearings for improper seating indicated by bright, polished sections of the bearing (3).
  28. If the lower half of the bearing is worn or damaged, both upper and lower halves should be replaced.

    Generally, if the lower half is suitable for use, the upper half should also be suitable for use.