Camshaft and Bearings Cleaning and Inspection

Tools Required: J 7872  Magnetic Base Dial Indicator Set

1. Clean the camshaft with cleaning solvent.
2. Inspect the camshaft for the following conditions:
   • Scored camshaft bearing journals (1)
   • Damaged camshaft lobes (2)
   • Damaged camshaft sprocket locator pins (3)
   • Damaged threads (4)
   Fig 1: Camshaft And Bearings

   Courtesy of GENERAL MOTORS CORP.
3. Measure the camshaft journals using a micrometer. If the camshaft journals are not within specifications, replace the camshaft.
   Fig 2: Measure The Camshaft Journals Using A Micrometer

   Courtesy of GENERAL MOTORS CORP.
4. Measure the camshaft runout using the J 7872.
   1. 4.1. Mount the camshaft in V-blocks between the centers.
   2. 4.2. Use the J 7872 in order to measure the intermediate camshaft journal.
5. Measure the camshaft lobe lift using the J 7872.
   1. 5.1. Lubricate the camshaft using GM P/N United States 12345501, GM P/N Canada 992704 or the equivalent.
   2. 5.2. Set the camshaft on V-blocks.
   3. 5.3. Use the J 7872 in order to measure the lobe lift.
6. If the runout or lobe lift is not within specifications, replace the camshaft.
   Fig 3: Measure The Camshaft Lobe Lift

   Courtesy of GENERAL MOTORS CORP.