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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1819 (Engine Mechanical - 3.5L (L66)) >> Repair Instructions >> Off Vehicle Repair Instructions >> Valve Guide Reaming/Valve and Seat Grinding >> Valve Seat Reconditioning

Valve Seat Reconditioning

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
    Fig 1: Using Seat Cutting Tool
    GM897387Courtesy of GENERAL MOTORS CORP.
    IMPORTANT: If the valve guides are worn, they must be replaced prior to cutting the valve seats.
  1. Renew the valve seats using a seat cutting tool.
    1. Carefully cut a 45 degree seat, removing only enough material to ensure a smooth and concentric seat.
    2. Bevel the upper edge of the seat with a 30 degree cutter.
    3. Bevel the lower edge of the intake valve seat with a 67 degree cutter.
    4. Bevel the lower edge of the exhaust valve seat with a 60 degree cutter.
    5. Make 1 additional light pass with a 45 degree cutter in order to remove any possible burrs created during the cutting process.

      Specification: 

      • Valve seat width - new: 1.25-1.55 mm (0.049-0.061 in)
      • Valve seat width - service limit: 2.0 mm (0.079 in)

    2. Fig 2: View Of Valve Seating Surface
    GM897388Courtesy of GENERAL MOTORS CORP.
  2. After resurfacing the valve and/or seat, inspect for even valve seating. Apply Gear Pattern Checking Grease GM P/N 1052351 (Canadian P/N 10953497), or equivalent, to the valve face (1). Insert the valve in its original location in the cylinder head. Lift and snap the valve closed against the seat several times.
  3. The actual valve seating surface (2) should be centered on the seat.
    • If the seat surface is too high or closer to the valve stem, a second cut with the 67 degree intake or 60 degree exhaust cutter must be made. An additional pass with the 45 degree cutter must also be made prior to completion.
    • If the seat surface is too low or closer to the large end of the valve, a second cut with the 30 degree cutter must be made. An additional pass with the 45 degree cutter must also be made prior to completion.
    4. Fig 3: Measuring Valve Stem Installed Height
    GM897389Courtesy of GENERAL MOTORS CORP.
  4. Insert the intake and exhaust valves into the cylinder head.
    1. Measure the valve stem installed height (a).
    2. If the valve stem installed height is over the service limit, replace the valve and measure again.
    3. If the installed height remains over the service limit, replace the cylinder head.

      Specification: 

      • Intake valve stem installed height - new: 46.75-47.55 mm (1.841-1.872 in)
      • Intake valve stem installed height - service limit: 47.8 mm (1.882 in)
      • Exhaust valve stem installed height - new: 46.68-47.48 mm (1.838-1.869 in)
      • Exhaust valve stem installed height - service limit: 47.73 mm (1.879 in)

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