GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Astro - 4WD 🢒 Engine 🢒 Engine Controls - 4.3L 🢒 Camshaft Timing Chain and Sprocket Replacement

Removal Procedure

    Object Number: 45986 Size: SH
  1. Remove the engine front cover. Refer to Engine Front Cover Replacement .
  2. Remove the crankshaft position sensor reluctor ring.

    3. Object Number: 480575 Size: SH

    Notice: 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.

    4. Notice: 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:
    5. 4.1. The timing marks on both sprockets line up.
    4.2. The number four cylinder is at top dead center (TDC) of the compression stroke.
  5. Remove the timing chain and sprockets. Refer to Timing Chain and Sprockets Removal .
  6. Clean and inspect the timing chain and sprockets. Refer to Camshaft Timing Chain and Sprocket Cleaning and Inspection .

Installation Procedure
  1. Install the timing chain and the sprockets. Refer to Timing Chain and Sprockets Installation .
  2. Remove the bolt from the crankshaft.

    3. Notice: Do not reuse the engine front cover. Oil leaks may result.

  3. Install the engine front cover. Refer to Engine Front Cover Replacement .