Camshaft and Bearings Cleaning and Inspection: Notes

Special Tools

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

For equivalent regional tools, refer to Special Tools .

Fig 1: View Of Camshaft Inspection Points
Courtesy of GENERAL MOTORS COMPANY
1. Clean the components in solvent.
WARNING:

Refer to Safety Glasses and Compressed Air Warning .

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: Camshaft Bearings
Courtesy of GENERAL MOTORS COMPANY
9. Inspect the camshaft bearings for the following:
   • Excessive wear, evidence of galling, pitting, scoring, or embedded debris. The appearance of the bearing material being different shades of gray are considered normal, and are not guideline for bearing replacement. Measure the bearing inside diameter (ID) as required for an over-sized condition. Refer to Engine Mechanical Specifications .
   • 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.
   • The oil lubrication feed hole in the bearing must be in alignment with the drilled out passage in the block.
   • The oil lubrication feed hole is not plugged by debris.
   • Bearings with excessive wear or scoring must be replaced.
   • Bearings with excessive wear, galling, pitting, scoring, or embedded debris must be replaced.
Fig 3: Measure Camshaft Journals With Micrometer
Courtesy of GENERAL MOTORS COMPANY
10. Using a micrometer, measure the camshaft journals for wear and out-of-round. Refer to Engine Mechanical Specifications .
    • If the camshaft bearing journals are out-of-round, replace the camshaft.
    • If the camshaft bearing journal diameter is not within specification, replace the camshaft.
Fig 4: Measuring Camshaft Lobes
Courtesy of GENERAL MOTORS COMPANY
11. Using a micrometer, measure the camshaft lobes for wear. Refer to Engine Mechanical Specifications .
Fig 5: Measuring Camshaft Runout
Courtesy of GENERAL MOTORS COMPANY
12. Measure the camshaft runout.
    1. Mount the camshaft in wooden V-blocks or between centers on a fixture.
    2. Using the J 7872  dial indicator set , measure the runout of the intermediate camshaft bearing journals.
    3. If camshaft runout is not within specification, the camshaft is bent and should be replaced. Refer to Engine Mechanical Specifications .