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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> Engine Mechanical >> Mechanical >> Engine Mechanical - 4.3L (On-Vehicle) >> Repair Instructions >> Timing Chain and Sprockets Replacement >> Removal Procedure

Removal Procedure

  1. Remove the engine front cover. Refer to Engine Front Cover Replacement .
  2. Remove the crankshaft position sensor reluctor ring.
    Fig 1: Crankshaft Position Sensor Reluctor Ring
    G01661194Courtesy of GENERAL MOTORS CORP.
    NOTE: In order to rotate the engine install a bolt with the same threads as the crankshaft, but do not use the crankshaft balancer bolt or a bolt longer than 1 inch, in the crankshaft. Failing to do so will cause damage to the bolt threads and the crankshaft threaded hole when removing the bolt.
  3. Install a 7/16-20 x 1 inch bolt into the end of the crankshaft.
    NOTE: Align the timing marks before removing the timing chain. If it is necessary to turn either the camshaft or the crankshaft with the timing chain removed, loosen or remove the valve rocker arms. Turning either the crankshaft or camshaft with the timing chain removed may cause the pistons to contact the valves, resulting in damage.
  4. Rotate the crankshaft until:
    1. 4.1. The timing marks on both sprockets line up.
    2. 4.2. The number four cylinder is at top dead center (TDC) of the compression stroke.
    Fig 2: Aligning Camshaft & Crankshaft Sprocket Timing Marks
    G01661195Courtesy of GENERAL MOTORS CORP.
  5. Remove the camshaft sprocket bolts.
    Fig 3: Camshaft Sprocket Bolt
    G01661196Courtesy of GENERAL MOTORS CORP.
  6. Remove the camshaft sprocket and the camshaft timing chain.
    Fig 4: Camshaft Sprocket & Timing Chain
    G01661197Courtesy of GENERAL MOTORS CORP.
  7. Remove the crankshaft sprocket using the J 5825-A. 
    Fig 5: Removing Crankshaft Sprocket Using J 5825-A
    G01661198Courtesy of GENERAL MOTORS CORP.
  8. Remove the crankshaft balancer key.
    Fig 6: Crankshaft Balancer Key
    G01661199Courtesy of GENERAL MOTORS CORP.
  9. Clean the components with cleaning solvent.
  10. Dry the components with compressed air.
  11. Inspect the camshaft timing chain for binding or wear.
    Fig 7: Camshaft Sprocket, Crankshaft Sprocket & Timing Chain
    G01661200Courtesy of GENERAL MOTORS CORP.
  12. Inspect the camshaft sprocket and the crankshaft sprocket for:
    • Broken teeth (1)
    • Damaged teeth (2)
    • Chipped teeth (3)
    • Worn teeth
    • Uneven wear on the edge of the teeth
    • Worn valleys between the sprocket teeth
    • Crankshaft sprocket keyway for wear
    Fig 8: Inspecting Camshaft & Crankshaft Sprockets
    G01661201Courtesy of GENERAL MOTORS CORP.
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