Valve Seat

Valve Seat, Rework Dimensions

Special tools, testers and auxiliary items required

• Depth gauge

• Valve seat refacing tool

Procedure

• 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 is particularly important on high mileage engines. 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.

- Camshafts, removing. Refer to --> [ Camshafts ] Camshafts.

Maximum Permitted Refacing Dimension is Calculated as Follows

- 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





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

Example





Reworking Intake Valve Seat









* How to calculate maximum permissible refacing dimension. Refer to --> [ Valve Seat, Rework Dimensions ] [1][2]Specifications.

Reworking Exhaust Valve Seat









* How to calculate maximum permissible refacing dimension. Refer to --> [ Valve Seat, Rework Dimensions ] [1][2]Specifications.