Valve Seat: Service and Repair

Valve seats, reworking

Special tools and equipment
^ Depth gauge
^ Valve seat re-facing tool

Note:
^ When repairing engines with leaking valves, it is not sufficient to rework or replace valve seats 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 begins. If the reworking dimension is exceeded, the function of the hydraulic lifters can no longer be guaranteed and the cylinder head should be replaced.

The maximum permissible reworking dimension is calculated as follows:
- 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 max. 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 = max. permissible reworking dimension.

Example:

Example:

Reworking intake valve seat

Reworking intake valve seat:

Reworking exhaust valve seat

Reworking exhaust valve seat: