Camshaft and Bearings Cleaning and Inspection (RPO LY6/L76/L92): Notes

Tools Required

• J 7872  Magnetic Base Dial Indicator Set
• J 8520  Camshaft Lobe Lift Indicator. See Special Tools .

Fig 1: View Of Camshaft Inspection Points
Courtesy of GENERAL MOTORS CORP.
1. Clean the components in solvent.
CAUTION: Refer to Safety Glasses and Compressed Air Caution .
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 camshaft position (CMP) actuator oil passages (3) for restrictions.
6. Inspect the threaded bolt hole (4) in the front of the camshaft for damaged threads or debris.
7. Inspect the camshaft sprocket pin (204) for damage.
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 Bearings
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 the engine block bearing bores.
10. Inspect the camshaft bearings for excessive wear or scoring.

    Bearings with excessive scoring or wear must be replaced.

Fig 3: Measure Camshaft Journals With Micrometer
Courtesy of GENERAL MOTORS CORP.
11. Using a micrometer, measure the camshaft journals for wear and out-of-round.
    • If the camshaft bearing journals are greater than 0.025 mm (0.001 in) out-of-round, replace the camshaft.
    • If the camshaft bearing journal diameter is less than 54.99 mm (2.164 in), replace the camshaft.
Fig 4: Measuring Camshaft Lobes
Courtesy of GENERAL MOTORS CORP.
12. Using a micrometer, measure the camshaft lobes for wear. Refer to Engine Mechanical Specifications (RPO LY2 VIN C) or Engine Mechanical Specifications (RPO LMG VIN 0) or Engine Mechanical Specifications (RPO LY5 VIN J) or Engine Mechanical Specifications (RPO LC9 VIN 3) or Engine Mechanical Specifications (RPO L76 VIN Y) or Engine Mechanical Specifications (RPO LY6 VIN K) or Engine Mechanical Specifications (RPO L92 VIN 8) .
Fig 5: Measuring Camshaft Runout
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. Using the J 7872  , measure the runout of the intermediate camshaft bearing journals.
    3. If camshaft runout exceeds 0.05 mm (0.002 in), the camshaft is bent and should be replaced.