Valve Seat Inspection/Repair

Measure the contact width of the valve face and the valve seat using the valve lapping compound.
- If it is not within the specification, resurface the valve seat using the 45° valve seat cutter.
Standard valve seat contact width 1.37-1.84 mm {0.0540-0.0724 in}

Valve seat angle 45°

Fig 1: Measuring Contact Width Of Valve Face And Valve Seat
Courtesy of MAZDA MOTORS CORP.
Verify that the area where the valve seat contacts the valve face is centered.
- If the seating position is too high, correct the valve seat using a 70° (IN) 70° (EX) valve seat cutter and a 45° valve seat cutter.
- If the seating position is too low, correct as follows:
  - IN: Correct the valve seat using a 20° valve seat cutter and then using a 45° valve cutter.
  - EX: Correct the valve seat using a 45° valve seat cutter.
    
    Fig 2: Identifying Intake/Exhaust Valve Seat Angle
    Courtesy of MAZDA MOTORS CORP.
Inspect the valve seat for sinkage. Measure the protruding length (dimension L) of the valve stem using a valve of standard length.
- If it is not within the specification, replace the cylinder head.
Standard valve seat sinkage amount (Dimension L)

IN: 48.93-50.17 mm {1.927-1.975 in}

EX: 48.87-50.11 mm {1.925-1.972 in}

Fig 3: Identifying Valve Stem Length
Courtesy of MAZDA MOTORS CORP.