Tools Required

SA9179NE  Dial Indicator. See Special Tools .

Fig 1: Identifying Different Crankshaft Journal Wear Patterns
Courtesy of GENERAL MOTORS CORP.
1. Clean the crankshaft oil passages. Remove all debris or restrictions.
2. Inspect the crankshaft for the following conditions:
   • Journals for wear (1)

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

   • Grooves or scoring (2)
   • Scratches or wear (3)
   • Pitting or imbedded material (4)
Fig 2: View Of Damaged Areas
Courtesy of GENERAL MOTORS CORP.
3. Inspect the key (1), keyway (2) and threaded holes (3) for damage.
Fig 3: View Of Front & Rear Upper Main Bearings
Courtesy of GENERAL MOTORS CORP.
4. Install the front and rear upper main bearings to the engine block.
5. Position the crankshaft in the engine block.
6. Use the SA9179NE  to measure the main journal runout. See Special Tools . Rotate the crankshaft two complete revolutions. The difference between the journal measurements must not exceed the service limit.

   Specification: 

   • Crankshaft total runout - new: 0.02 mm (0.0008 in)
   • Crankshaft total runout - service limit: 0.03 mm (0.0012 in)

7. Measure the main and connecting rod journals for an out-of-round condition. Measure each journal in 2 places 90 degrees opposite each other. The difference between the measurements on each journal must not exceed the service limit.

   Specification: 

   • Journal out-of-round - new: 0.005 mm (0.0002 in)
   • Journal out-of-round - service limit: 0.01 mm (0.0004 in)

Fig 4: Measuring The Main & Connecting Rod Journals
Courtesy of GENERAL MOTORS CORP.
8. Measure the main and connecting rod journals for excessive taper. Measure each journal at the edges (1).

   Specification: 

   • Journal taper - new: 0.005 mm (0.0002 in)
   • Journal taper - service limit: 0.01 mm (0.0004 in)