Valve Seat

Valve Seats Reworking Dimensions

• If a perfect contact pattern is not achieved by grinding the valve seats, rework the valve seats.

Special tools, testers and auxiliary items required

• Depth gauge

• Valve seat refacing tool

• 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 higher mileage. Refer to => [ Valve Guides, Checking ] Testing and Inspection.

• 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 and therefore the cylinder head should be replaced.

Calculating Maximum Allowable Reworking Dimension

- Insert valve and press it firmly against the valve 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 camshaft center axle (camshaft center axle is located at the level of the cylinder head upper edge).






- Calculate max. permissible reworking dimension from measured distance and minimum dimension.






Measured distance minus minimum dimension = max. permissible reworking dimension.






• If the maximum permissible reworked 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, Reworking