Note. If a good seating pattern cannot be obtained by grinding the valve seats (lapping), they must be refaced (machined).
Special tools and equipment required
- Depth gauge
- Valve seat machining tool
Note. When servicing engines with leaking valves, it is not sufficient to machine (reface) the valve seats and replace the valves. The valve guides must also be checked for wear. This is particularly important on high-mileage engines. Refer to Valve guides, checking Valve seats should only be machined to the extent required to give a proper seating pattern. The maximum permissible machining dimension must be calculated before starting work. If the machining dimension is exceeded, the function of the hydraulic valve play compensation can no longer be guaranteed and the cylinder head must be replaced.