Valve Seat: Service and Repair

Valve seats, refacing

Note: If a perfect contact pattern isn't created after hand-lapping valve seats' reface valve seats.

Special Tools and Equipment
^ Depth gauge
^ Valve seat refacing tool

Notes:
^ When servicing engines with leaking valves, refacing or replacing valve seats and valves is not sufficient. It is particularly important to check valve guides for wear on engines with higher mileage performance, Refer to Valve Guide, Testing and Inspection.
^ Only reface valve seats enough until a perfect contact pattern is obtained.
^ Before refacing, determine maximum refacing dimension.
^ If refaced dimension is exceeded, hydraulic valve lifter function is no longer guaranteed and cylinder head must be replaced.

Determining maximum allowable refacing dimension
- Insert valve and press tightly against valve seat.

Note: If valve is replaced during repair, use new valve for measurement.





- Measure distance -a- between valve stem end (upper edge) and upper cylinder head surface using a depth gauge.





- Determine maximum allowable refacing dimension using distance measured and minimum dimension.





Distance measured minus minimum dimension = maximum permissible refacing dimension.

Note: If the maximum allowed refaced dimension is 0 mm or less than 0 mm, repeat measurement using new valve. If measurement result is still 0 mm or less than 0 mm, replace cylinder head.











Valve seats, refacing