SEAT Workshop Service and Repair Manuals

Valve seats: subsequent grinding Special tools and workshop equipment required t  Gauge t  Valve seat refacing tool   Note t  When repairing engines with non airtight valves, it is not enough to reface or to replace the valve seatings and the valves. The valve guides must also be checked for wear. This is particularly important on high mileage engines → Chapter. t  The valve seats should only be reworked just enough to produce a good seating pattern. Before refacing, the max. allowable refacing value must be calculated. If the reworking dimension is exceeded, hydraulic valve compensation can no longer be guaranteed and the cylinder head should be renewed. Calculate the maximum permissible reworking level as follows: –  Insert valve and press firmly against valve seat.   Note If the valve is to be renewed as part of a repair, use a new valve for the calculation.

–  Measure distance between end of valve stem and upper edge of cylinder head. –  Calculate maximum permissible reworking dimension from measured distance and minimum dimension. Minimum dimension: Inlet valve 7.6 mm, Outlet valve 7.6 mm Measured distance = max. permissible minimum dimension. Example:

	Distance measured Minimum distance	8,0 7,6	mm mm
=	Max. permissible reworking dim. 2	0,4	mm

1)  The maximum permissible reworking dimension is shown on illustrations as dimension “b” .

Exhast valve seat: Reworking

a b c Z α β γ

= Ø 28.7 mm = maximum permitted reworking dimension1 = 1.5-1.8 mm = cylinder head lower edge = 45 ° valve seat angle = 30 ° upper correction angle = 60 ° lower correction angle

Exhast valve seat: Reworking

a b c Z α β γ

= Ø 25.0 mm = maximum permitted reworking dimension1 = approx. 1.8 mm = cylinder head lower edge = 45 ° valve seat angle = 30 ° upper correction angle = 60 ° lower correction angle

2)  Calculating maximum permissible reworking dimension → Chapter