Volkswagen Workshop Service and Repair Manuals

Reworking valve seats Special tools and workshop equipment required t  Depth gauge t  Valve seat refacing tool   Note t  When repairing engines with leaking valves, it is not sufficient to reface or renew valve seats and valves. There is also a requirement to check the valve guides for wear. This particularly important on high mileage engines. t  Valve seats should be reworked only enough to produce a perfect seating pattern. Before beginning to rework valve seats, calculate the maximum permissible reworking dimension. If the reworking dimension is exceeded, hydraulic valve compensation can no longer be guaranteed and the cylinder head should be renewed. The max. permissible reworking dimension is calculated as follows: –  Insert valve and press firmly against seat.   Note If the valve is to be renewed 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 maximum permissible reworking dimension from measured distance -a- and minimum dimension. Minimum dimension: inlet valve 33.8 mm, exhaust valve 34.1 mm Measured distance -a- minus minimum dimension = maximum permissible reworking dimension. Example:

Measured distance -a-	35,1	mm
Minimum dimension	34,1	mm
Max. perm. rework dimension → Note	1,0	mm

1)  The max. permissible reworking dimension is shown on illustrations for reworking valve seats as dimension “b”.

Reworking inlet valve seat

Dimension		Inlet valve seat
Ø a	mm	39,2
b	mm	Max. permissible rework dimension
c	mm	1,8…2,2
Z		Lower edge of cylinder head
45°		Valve seat angle
30°		Upper correction angle

Reworking exhaust valve

Dimension		Exhaust valve seat
Ø a	mm	32,4
Ø b	mm	Max. permissible rework dimension
c	mm	2,2…2,6
Z		Lower edge of cylinder head
45°		Valve seat angle
30°		Upper correction angle