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Valve Cleaning and Inspection

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  1. Fig 1: Identifying Valve Inspection Areas
    GM2371863Courtesy of GENERAL MOTORS COMPANY
    NOTE:

    Do not use a wire brush on any part of the valve stem.

    NOTE:

    Do not grind or condition the intake valve. If the intake valve is out of specification, replace the valve.

    Clean the valves of carbon, oil and varnish. Use a soft bristle wire brush to clean any carbon build-up from the valve head. Varnish can be removed by soaking in Parts Immersion Solvent. Refer to Adhesives, Fluids, Lubricants, and Sealers .

  2. Clean the valve guides.
  3. Inspect the valve stem for pitting or wear (4).
  4. Inspect the valve key groove for chipping or wear (5). Replace the valve if chipped or worn.
  5. Inspect the valve face for burning or cracking (1). If pieces are broken off, inspect the corresponding piston and cylinder head area for damage.
  6. Inspect the valve stem for burrs and scratches. Burrs and minor scratches may be removed with an oil stone.
  7. Inspect the valve stem for straightness (3) and the valve head for bending or distortion using V blocks. Bent or distorted valves must be replaced.
  8. Clean the deposits from the valve face. Inspect the valve face for grooving.
  9. Replace the valve if the face is grooved. Valve faces cannot be machined. If worn, or damaged, the valves must be replaced.
  10. Replace the valve if the valve head O.D. and chamfer (2) is worn or out of specification. Refer to Valve and Seat Grinding .
  11. The valves may be lightly lapped to the valve seats.
  12. Replace the valve if the valve tip (6) is worn.
  13. If no apparent wear, pitting, grooving, or distortion is present, perform the valve measurement and reconditioning procedure to verify valve specification. Refer to Valve and Seat Grinding .