FOX 2004 ➤
3 - Cyl. injection engine - Edition 12.2009
♦ Depth vernier caliper
♦ Device for grinding valve seats
Note
♦ In case of repairs to engines with leaking valves, simply grind‐
ing or replacing the seats and valves is not enough. Especially
in engines with high kilometres traveled, the valve guides must
also be checked for wear. ⇒ page 42 .
♦ Grind valve seats until obtaining a perfect seating. Before
grinding, determine the maximum grinding elevation allowed.
If grinding elevation is exceeded, hydraulic offsetting of valve
clearance is no longer ensured and the engine cylinder head
must be replaced.
lk
Calculating maximum trimming specification allowed
– Install the valve and press it strongly against its seat.
Note
If the valve is replaced upon repair, use the new valve for meas‐
urement.
– Measure the distance -a- between valve end and engine head
upper surface.
– Calculate maximum and minimum grinding measurement of
the measured distance.
Minimum measurements: Intake valve = 7.6 mm and exhaust
valve = 7.6 mm.
Measured distance minus minimum distance = Maximum grinding
measurement allowed.
Example:
Measured distance
8,0 mm
7,6 mm
- minimum specification
Maximum allowable grinding specification
0,4 mm
The max. grinding measurement allowed is shown in the illustra‐
tions to grind the valve seats as per measurement “b”.
Grind intake valve seats
a
b
c
= Ø32,9 mm
= max. trimming specification allowed
= max. 1.8...2.0 mm
Z
a
ß
?
= Lower cylinder head edge
= 45° Valve seat angle
= 30° Upper correction angle
= 60° Lower correction angle
3) Calculating maximum grinding measurement allowed ⇒ page 40 .
2. Camshaft mechanism - repair
41
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