SEAT 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 always sufficient to reface or renew valve seats and valves. It is also necessary to check the valve guides for wear. This particularly important on high mileage engines. t  The valve seats should only be reworked just enough to produce a perfect seating pattern. The maximum permissible reworking dimension must be calculated before reworking commences. If the reworking dimension is exceeded, the function of the hydraulic tappets 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 max. 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 = max. 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

Dim.		Inlet valve seat
Ø a	mm	39,2
b	mm	max. permissible reworking dim.
c	mm	approx. 2.0
Z		Cylinder head lower edge
45°		Valve seat angle
30°		Upper correction angle

Reworking exhaust valve seat

Dim.		Exhaust valve seat
Ø a	mm	32,4
b	mm	max. permissible reworking dim.
c	mm	approx. 2.4
Z		Cylinder head lower edge
45°		Valve seat angle
30°		Upper correction angle

Note! Exhaust valve seat inserts also have an additional internal constriction. When reworking ensure that the radius of the constriction is not damaged.