Inspection Procedure

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 Chevrolet Tahoe, 2002 Chevrolet Suburban, and 2002 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

IMPORTANT: The 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.

Perform a visual inspection of the crankshaft for damage.
Inspect the crankshaft position reluctor ring lobes for damage.

Fig 1: Crankshaft Removed
Courtesy of GENERAL MOTORS CORP.
Inspect the crankshaft journals for wear (1).
Journals should be smooth with no signs of scoring, wear, or damage.
Inspect the crankshaft journals for grooves or scoring (2).
Inspect the crankshaft journals for scratches or wear (3).
Inspect the crankshaft journals for pitting or imbedded bearing material (4).

Fig 2: Crankshaft Inspection Areas
Courtesy of GENERAL MOTORS CORP.
Inspect the crankshaft key (1), keyway (2), and threaded hole (3) for damage.

Fig 3: Crankshaft Key, Keyway & Threaded Hole
Courtesy of GENERAL MOTORS CORP.
Measure the crankpins for the out-of-round.
Measure the crankpins for taper.

Fig 4: Measuring Crankpins
Courtesy of GENERAL MOTORS CORP.
Measure the crankshaft thrust wall width.
A crankshaft with a thrust wall width in excess of 26.2 mm (1.0315 in) must be replaced.

Fig 5: Measuring Crankshaft Thrust Wall Width
Courtesy of GENERAL MOTORS CORP.
Measure the crankshaft runout.
Use wooden V blocks or a fixture to support the crankshaft on the front and rear journals.
Use the J 7872 in order to measure the crankshaft runout at the front and rear intermediate journals.
Use the J 7872 in order to measure the runout of the crankshaft rear flange.
Use the J 7872 in order to measure the runout of the crankshaft position reluctor ring. Reluctor ring runout should be measured 1.0 mm (0.04 in) below the ring teeth.
If the reluctor ring has runout in excess of 0.7 mm (0.028 in), replace the crankshaft.

Fig 6: Measuring Crankshaft Rear Flange & Crankshaft Position Reluctor Ring Using J 7872
Courtesy of GENERAL MOTORS CORP.
Inspect crankshaft bearings for craters or pockets. Flattened sections on the bearing halves also indicate fatigue.

Fig 7: Crankshaft Bearing W/Craters
Courtesy of GENERAL MOTORS CORP.
Inspect the crankshaft bearings for excessive scoring or discoloration.
Inspect the crankshaft bearings for dirt or debris imbedded into the bearing material.

Fig 8: Crankshaft Bearings W/Excessive Scoring, Dirt & Debris
Courtesy of GENERAL MOTORS CORP.
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 9: Crankshaft Bearing W/Polished Sections
Courtesy of GENERAL MOTORS CORP.