Volkswagen Workshop Service and Repair Manuals

Reworking valve seats Special tools and workshop equipment required t  Depth gauge t  Valve seat reworker   Note t  When repairing engines with leaking valves, it is not sufficient to rework valve seats and/or renew valves. With engines that have many miles on the clock, check valve guides for wear. t  Only rework valve seats until surface appearance is correct. Before starting rework, calculate the max. permissible rework dimension. If the rework dimension is exceeded, the function of the hydraulic valve clearance adjustment system is no longer assured and the cylinder head must be renewed. The max. permitted rework dimension is calculated as follows: –  Insert valve and press firmly against valve seat.   Note If valve is renewed as part of repair job, use it to measure new valve.

–  Measure clearance -a- between end of valve stem and top edge cylinder head. –  Calculate max. permissible rework dimension from measured clearance -a- and minimum dimension. Minimum dimensions: inlet valve 33.8 mm; exhaust valve 34.1 mm Measured clearance -a- less minimum dimension = max. permissible rework dimension Example:

Measured clearance -a-	35.1	mm
Minimum dimension	34.1	mm
Max. perm. rework dimension → Note	1,0	mm

1)  The max. perm. rework dimension is represented in illustrations for reworking valve seats as dimension “b”.

Reworking inlet valve seat

Dimension		Inlet valve seat
Ø a	mm	39.2
b	mm	Max. perm. rework dimension
c	mm	1.8…2.2
Z		Bottom edge cylinder head
45°		Valve seat angle
30°		Top correction angle

Reworking exhaust valve seat

Dimension		Exhaust valve seat
Ø a	mm	32.4
Ø b	mm	Max. perm. rework dimension
c	mm	2.2…2.6
Z		Bottom edge cylinder head
45°		Valve seat angle
30°		Top correction angle