Chevrolet Silverado / GMC Sierra. Service manual — part 346

Fig. 400: Measuring Crankshaft Thrust Wall Width
Courtesy of GENERAL MOTORS CORP.

9. Measure the crankshaft thrust wall width.

A crankshaft with a thrust wall width in excess of 26.2 mm (1.0315 in) (a) must be replaced.

Fig. 401: Measuring Crankshaft Runout

2008 Hummer H2

2008 ENGINE Engine Mechanical - 6.2L - H2

Courtesy of GENERAL MOTORS CORP.

10. Measure the crankshaft runout.

Use wooden V-blocks or a fixture to support the crankshaft on the front and rear journals.

11. Use the J 7872 in order to measure the crankshaft runout at the front and rear intermediate

journals.

12. Use the J 7872 in order to measure the runout of the crankshaft rear flange.

13. 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. 402: Identifying Crankshaft Bearing Craters Or Pockets
Courtesy of GENERAL MOTORS CORP.

14. Inspect crankshaft bearings for craters or pockets. Flattened sections on the bearing halves

also indicate fatigue.

2008 Hummer H2

2008 ENGINE Engine Mechanical - 6.2L - H2

Fig. 403: Identifying Connecting Rod Bearing Scoring Or Discoloration
Courtesy of GENERAL MOTORS CORP.

15. Inspect the crankshaft bearings for excessive scoring or discoloration.

16. Inspect the crankshaft bearings for dirt or debris imbedded into the bearing material.

2008 Hummer H2

2008 ENGINE Engine Mechanical - 6.2L - H2

Fig. 404: View Of Improper Seating
Courtesy of GENERAL MOTORS CORP.

17. 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.

Measuring Main Bearing Clearance - Gaging Plastic Method

2008 Hummer H2

2008 ENGINE Engine Mechanical - 6.2L - H2