Camshaft and Bearings Cleaning and Inspection: Notes

Tools Required

• J 7872  Magnetic Base Dial Indicator Set
• J 8520  Cam Lobe Lift Indicator

1. Clean the components in solvent.
CAUTION: Refer to Safety Glasses Caution in Cautions and Notices.
2. Dry the components with compressed air.
3. Inspect the camshaft bearing journals (1) for scoring or excessive wear.
4. Inspect the camshaft valve lifter lobes (2) for scoring or excessive wear.
5. Inspect the threaded bolt holes (3) in the front of the camshaft for damaged threads or debris.
6. Inspect the camshaft sprocket pin (204) for damage.
7. Inspect the camshaft position (CMP) reluctor ring for nicks or damage.
Fig 1: Identifying Camshaft & Bearing Inspection Areas
Courtesy of GENERAL MOTORS CORP.
8. Inspect the camshaft retainer plate for wear or a damaged sealing gasket.

   If the camshaft retainer plate sealing gasket is not cut or damaged, it may be used again.

Fig 2: View Of Camshaft Retainer Plate
Courtesy of GENERAL MOTORS CORP.
9. Inspect the camshaft bearings for proper fit in the engine block. Camshaft bearings have an interference fit to the engine block and should not be loose in their engine block bearing bores.
Fig 3: View Of Camshaft Bearings
Courtesy of GENERAL MOTORS CORP.
10. Inspect the camshaft bearings for excessive wear or scoring.

    Bearings with excessive scoring or wear must be replaced.

11. Measure the camshaft journals for wear and out-of-round with a micrometer.
    • If the camshaft bearing journals are more than 0.025 mm (0.001 in) out-of-round, replace the camshaft.
    • If the camshaft bearing journal diameter is less that 54.99 mm (2.164 in), replace the camshaft.
Fig 4: Measure Camshaft Journals With Micrometer
Courtesy of GENERAL MOTORS CORP.
12. Measure the camshaft lobes for wear with a micrometer.
    • A 4.8/5.3L camshaft with an intake lobe that measures 46.169 mm (1.817 in) or less must be replaced.
    • A 4.8/5.3L camshaft with an exhaust lobe that measures 46.199 mm (1.818 in) or less must be replaced.
    • A 6.0L camshaft with an intake lobe that measures 46.31 mm (1.823 in) or less must be replaced.
    • A 6.0L camshaft with an exhaust lobe that measures 46.48 mm (1.83 in) or less must be replaced.
Fig 5: Measuring Camshaft Lobes
Courtesy of GENERAL MOTORS CORP.
13. Measure the camshaft runout.
    1. Mount the camshaft in wooden V blocks or between centers on a fixture.
    2. Check the runout of the intermediate camshaft bearing journals using theJ 7872  .
    3. If camshaft runout exceeds 0.05 mm (0.002 in), the camshaft is bent and should be replaced.
Fig 6: Measuring Camshaft Runout
Courtesy of GENERAL MOTORS CORP.