SEAT Workshop Service and Repair Manuals

Valve seats: Reworking t  Calculating maximum permissible reworking dimension → Anchor t  Inlet valve seat: reworking → Anchor t  Exhaust valve seat, reworking → Anchor Special tools and workshop equipment required t  Depth gauge t  Valve seat re-facing tool   Note t  When repairing engines with non airtight valves, it is not enough to reface or to replace the valve seats 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. The maximum permissible reworking dimension must be calculated before reworking commences → Anchor If the reworking dimension is exceeded, hydraulic valve compensation can no longer be guaranteed and the cylinder head should be renewed. Maximum permissible reworking dimension: calculation –  Insert valve and press firmly against valve seat.   Note If a valve is to be replaced during a repair, use a new valve for the calculation.

–  Measure with a depth gauge the distance -a- between end of valve stem (upper edge) and upper cylinder head surface. –  Calculate the maximum reworking measurement starting from the measured distance -a- and the minimum measurement.

Minimum dimensions
Supply valves	Exhaust valves
31.7 mm	31.7 mm

Measured distance -a- minus minimum dimension = max. permissible machining dimension.

Example:
	Measured distance -a-		32.0 mm
-	Minimum dimension		31.7 mm
=	Max. permissible reworking dimension → Remark		= 0.3 mm

1)  The maximum permissible reworking dimension is shown on illustrations as dimension „b“ .   Note If the maximum permissible reworking dimension is 0 mm or less than 0 mm, repeat the measurement with a new valve. If the measured result is again 0 mm or less than 0 mm, replace the cylinder head.

Exhaust valve seat, reworking

Dim.		Inlet valve seat:
Ø a	mm	39,2
b	mm	Max. permissible reworking dimension
c	mm	1,8 ... 2,2
Z		Lower edge of cylinder head
45°		Valve seating angle
30°		upper correction angle

Note Calculating maximum permissible machining dimension → Anchor.

Exhaust valve seat, reworking

Dim.		Exhaust valve seat:
Ø a	mm	32,4
Ø b	mm	Max. permissible reworking dimension
c	mm	2,2 ... 2,6
Z		Lower edge of cylinder head
45°		Valve seating angle
30°		upper correction angle

Note t  Calculating maximum permissible machining dimension → Anchor. t  Exhaust valve seat inserts have additionally a restriction. When reworking observe that the radius of the restriction is not damaged.