Tools Required

J 7872  Magnetic Base Dial Indicator Set

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 effect OBD II system performance.

1. Clean the crankshaft with solvent.
2. Thoroughly clean all oil passages and inspect for restrictions or burrs.
3. Dry the crankshaft with compressed air.
   Fig 1: Cleaning Crankshaft

   Courtesy of GENERAL MOTORS CORP.

   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.

4. Perform a visual inspection of the crankshaft for damage.
5. Inspect the crankshaft journals for wear (1).

   Journals should be smooth with no signs of scoring, wear, or damage.

6. Inspect the crankshaft journals for grooves or scoring (2).
7. Inspect the crankshaft journals for scratches or wear (3).
8. Inspect the crankshaft journals for pitting or imbedded bearing material (4).
   Fig 2: Inspecting Crankshaft

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9. Measure the crankshaft journals for out-of-round.
10. Measure the crankshaft journals for taper.
    Fig 3: Measuring Crankshaft Journals

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11. Measure the crankshaft runout.

    Using wooden V blocks, support the crankshaft on the front and rear journals.

12. Use the J 7872  in order to measure the crankshaft runout at the front and rear intermediate journals.
13. Use the J 7872  in order to measure the runout of the crankshaft rear flange.
14. Replace the crankshaft if the measurements are not within specifications.
    Fig 4: Measuring Crankshaft Runout

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15. Inspect crankshaft bearings for craters or pockets. Flattened sections on the bearing halves also indicate fatigue.
    Fig 5: Inspecting Crankshaft Bearings For Craters Or Pockets

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16. Inspect the crankshaft bearings for excessive scoring or discoloration.
17. Inspect the crankshaft bearings for dirt or debris imbedded into the bearing material.
    Fig 6: Inspecting Crankshaft Bearings For Excessive Scoring Or Discoloration

    Courtesy of GENERAL MOTORS CORP.
18. Inspect the crankshaft bearings for improper seating indicated by bright, polished sections of the bearing.

    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.

    Fig 7: Inspecting Crankshaft Bearings For Improper Seating

    Courtesy of GENERAL MOTORS CORP.