Valve Seat: Service and Repair

Valve Seats, Reworking

Special tools, testers and auxiliary items required

• Depth gauge

• Valve seat refacing tool

Perform the following:

• When repairing engines with leaking valves, it is not sufficient to rework or replace valve seats and valves. It is particularly important to check valve guides for wear on engines with longer running times.

• Only reface valve seats enough until a perfect contact pattern is obtained. The maximum permissible reworking dimension must be calculated before work is carried out. If the reworking dimension is exceeded, the function of the hydraulic lifters can no longer be guaranteed. Therefore the cylinder head should be replaced.

Calculate the maximum reworking dimension:

- Insert valve and press firmly against seat.

• If the valve is to be replaced as part of a repair, use a 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 - 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:






1)Maximum allowable refacing dimension is represented in illustrations for refacing valve seats as dimension "b".

Reworking intake valve seat











Reworking exhaust valve seat