Valve Seat: Service and Repair

Valve seats, reworking

Special tools, testers, measuring instruments and auxiliary items required
^ Depth gauge
^ Valve seat refacing tool

Note:
^ When repairing engines with leaking valves, it is not sufficient to rework or replace valve and valves. It is also necessary to check the valve guides for wear. This particularly important on high mileage engines.
^ The valve seats should only be reworked just enough to produce a perfect seating pattern. The maximum permissible reworking dimension must be calculated before reworking commences. If the reworking dimension is exceeded, the function of the hydraulic lifters can no longer be guaranteed and the cylinder head should be replaced.

Calculating maximum permissible reworking dimension
^ Insert valve and press firmly against seat.

Note: If the valve is to be replaced as part of a repair, use a new valve for the measuring.





^ Measure distance -a- between end of valve stem and upper edge of cylinder head.
^ Calculate maximum permissible reworking dimension from measured distance -a- and minimum dimension.
Minimum dimensions:
Intake valve 33.8 mm
Exhaust valve 34.1 mm

Measured distance -a- minus minimum dimension = maximum permissible reworking dimension.





Example:

Part 1:

Part 2:

Reworking intake valve seat

Part 1:

Part 2:

Reworking exhaust valve seat