Skoda FABIA 2000 Workshop Manual page 60

15
Fig. 5: Reworking lower cylinder head sealing sur-
face
Permissible reworking dimension of cylinder head: a = at
least 108.25 mm.
Reworking valve seats
Special tools, test and measuring equipment and
auxiliary items required
♦ Depth gauge
♦
NAC milling cutter for reworking valve seats
Note
♦
When carrying out repairs on engines with leaking
valves, it is not sufficient to machine or replace the
valve seats and valves. It is also necessary to inspect
the valve guides for wear, particularly on engines with
a high mileage ⇒ 15-2 page 7.
♦ Rework valve seats only sufficiently in order to obtain
a proper contact pattern. Calculate the maximum per-
missible reworking dimension before commencing. If
the reworking dimension is exceeded, the proper op-
eration of the hydraulic valve clearance compensation
is no longer ensured. If this is the case replace the cyl-
inder head.
Calculating maximum permissible reworking di-
mension
–
Insert valve into the guide and press firmly against the
valve seat.
Note
If the valve is replaced when carrying out repair work, use
a new valve for the measurement.
–
Measure distance between the valve stem end and
the upper face of the cylinder head.
–
Calculate max. permissible reworking dimension from
the distance measured and the minimum dimension.
Minimum dimension: Inlet
valve
Minimum dimension: Ex-
haust valve
„Measured distance" - „minimum dimension" = „max. per-
missible reworking dimension".
Example:
Measured distance
- Minimum dimension
= max. permissible reworking dimension
15-2 4
page
FABIA 2000
7.6 mm
7.6 mm
8.0 mm
7.6 mm
0.4 mm
1)
Repairing Valve Gear
1.4/55; 1.4/74 Engine - Mechanical Components
Edition 05.05
S00.5306.06.20