Valve Seat: Service and Repair

Valve Seats, Reworking

Special tools and equipment

- Depth gauge

- Valve seat refacing tool

Note:

- When repairing engines with leaking valves, it is not always sufficient to reface or replace valve seats and valves. It is also necessary to check the valve guides for wear. This is particularly important on high mileage engines.
- The valve seats should only be reworked enough to produce a symmetrical seating pattern. The Maximum permissible reworking dimension must be calculated before reworking begins. If this dimension is exceeded, proper function of the hydraulic lifters can no longer be guaranteed and the cylinder head must 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 the new valve for the calculation.






- Measure distance -a- between end of valve stem and upper edge of cylinder head.

- Calculate Max. permissible reworking dimension from measured distance -a- MINUS the minimum dimension.

Minimum dimension:

- Intake valve 33.8 mm
- Exhaust valve 34.1 mm

Measured distance MINUS the minimum dimension = Maximum permissible reworking dimension.


Example:






*) The Max. permissible reworking dimension is shown on illustrations for reworking valve seats as dimension "b".

Intake valve seat, reworking











Exhaust valve seat, reworking











Note:

- Exhaust valve seat rings also have a reduced inner diameter. When reworking, ensure the reduction radius is not damaged.