Volkswagen Fox 2004 Workshop Manual page 58

Fox 2004 ➤
3 - Cyl. diesel engine - Edition 02.2009
Note
In case of repairs to engines with leaking valves, simply re‐
♦
working or replacing the seats and valves is insufficient. Es‐
pecially in engines with high milage, the valve guides must
also be checked for wear.
The valve seats should only be sufficiently reworked to pro‐
♦
duce a perfect seating pattern. The maximum reworking di‐
mension must be calculated before undertaking the tasks.
When the rework measurement is exceeded, the hydraulic
compensation function of the tappets will not be guaranteed,
and the engine head must be replaced.
2.1.1 Calculating the maximum reworking di‐
mension allowed
– Install valve and firmly press it against seat.
Note
In case the valve is replaced during repairs, use new valve for
measurement.
– Measure the distance -a- between valve stem end and engine
head upper edge.
– Calculate max. permissible reworking dimension from meas‐
ured distance -a-and minimum dimension.
Minimum dimensions: Intake valve 43.4 mm Escape valve 43.2
mm.
Distance measured minus minimum distance = maximum per‐
mitted reworking dimension.
Example:
- Measured distance
Minimum dimension
= Max. reworking dimension perm.
2.1.2 Reworking intake valve seat
a =∅35.7 mm
b = 1.6 mm
45° = Valve seat angle
Note
. The 30° angle in the valve seat base is crucial for ensuring the
correct gas flow.
54
Rep. Gr.15 - Cylinder head, valve control mechanism
44,1 mm
43,4 mm
0,7 mm