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Procedure
Note
♦
When repairing engines with leaking valves, it is not sufficient
to rework or renew valve seats and valves. Particularly on high
mileage engines, it is necessary also to check valve guides for
wear
⇒ page 91
.
♦
Valve seats should be reworked only enough to produce a
perfect seating pattern. Before beginning to rework valve
seats, calculate the maximum permissible reworking dimen‐
sions. If the reworking dimension is exceeded, hydraulic valve
compensation can no longer be guaranteed and the cylinder
head should be renewed.
– Remove camshafts,
⇒ page 82
.
The max. permissible reworking dimension is calculated as fol‐
lows:
– 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 maximum permissible reworking dimension from
measured distance -a- and minimum dimension.
Minimum dimension:
Short inlet valve
mm
31.8
Long inlet valve
mm
10.2
Short exhaust valve
mm
31.8
Long exhaust valve
mm
10.2
Measured distance minus minimum dimension = max. permissi‐
ble reworking dimension.
Example:
- Measured distance
Minimum dimension
10.6
10.2
mm
mm
= max. perm. rework dimension
5)
0.4 mm
5) The max. permissible reworking dimension is shown as dimension “b” in the
illustrations for reworking valve seats.
Phaeton 2003 ➤
6-cylinder injection engine - Edition 02.2014
92
Rep. gr.15 - Cylinder head, valve gear
