Camshaft and Bearings Cleaning and Inspection

Tools Required 

J 7872  Magnetic Base Dial Indicator

CAUTION: Refer to Safety Glasses Caution in Cautions and Notices.
1. Clean the engine camshaft in cleaning solvent.
2. Dry the engine camshaft with compressed air.
3. Inspect the camshaft retainer plate for damage.

   If the camshaft retainer plate is damaged, replace as necessary.

Fig 1: Camshaft & Retainer Plate
Courtesy of GENERAL MOTORS CORP.
4. Inspect the camshaft bearings for correct fit into the engine block camshaft bearing bores.

   The camshaft bearings have an interference fit to the engine block camshaft bearing bores and must not be loose in the engine block camshaft bearing bores.

IMPORTANT: If any camshaft bearing is excessively worn or scored, replace all the camshaft bearings.
5. Inspect the camshaft bearings for excessive wear or scoring.
6. Inspect the engine camshaft for the following:
   • Worn, scored, or damaged bearing journals (1)
   • Worn engine camshaft lobes (2)
   • Damaged bolt hole threads (3)
   • Damaged camshaft sprocket locator pin (4)
Fig 2: Camshaft Inspection Areas
Courtesy of GENERAL MOTORS CORP.
7. Measure the engine camshaft journals with a micrometer.

   If the camshaft journals are more than 0.025 mm (0.0010 in) out-of-round, then replace the engine camshaft.

Fig 3: Measuring Engine Camshaft Journals
Courtesy of GENERAL MOTORS CORP.
8. Measure for a bent engine camshaft or excessive engine camshaft runout using the J 7872  .
   1. Mount the engine camshaft in a suitable stand between centers.
   2. Use the J 7872  in order to check the intermediate engine camshaft journals.

      If the runout exceeds 0.065 mm (0.0026 in), the engine camshaft is bent and must be replaced.

Fig 4: Measuring The Engine Camshaft Lobe Lift Usingj 7872
Courtesy of GENERAL MOTORS CORP.
9. Measure the engine camshaft lobe lift using the J 7872  .
   1. Place the engine camshaft on the V-blocks.
   2. Use the J 7872  in order to measure the engine camshaft lobe lift.
10. Replace the engine camshaft if the engine camshaft lobe lift is not within specifications. Refer to Engine Mechanical Specifications .