Volkswagen Passat 1995 Official Factory Repair Manual page 360

Cylinder head, disassembling and assembling
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Valve seats, refacing
CAUTION!
When refacing valve seats, remove only
enough material to produce the correct seat
contact pattern. The maximum permissible
refacing dimension for the cylinder head
must be calculated before refacing.
If the maximum permissible head refacing
dimension is exceeded, the hydraulic lifters
will not function properly and the cylinder
head must be replaced.
Note:
When repairing engines with leaking valves, it is
not always sufficient to replace or replace valve
seats and valves. It is also necessary to check
the valve guides for wear. This particularly
important on high-mileage engines.
Calculating max. permissible refacing
dimension
- Insert valve and press firmly against seat.
Note:
If the valve is to be replaced as part of a repair,
use a new valve for the measurement and
calculation.
- Measure distance -a- between center of valve
stem and top edge of cylinder head.
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5/12/2004