3
113
E
N
G
IN
E ASS
E
M
B
LY AN
D CO
NTRO
LS
Extraction of valve stem seals from valve stems.
Checking flatness of cylinder head.
3.17.4.3
VALVE STEM SEAL AND LO-
WER STOP WASHER
Should there be excessive oil consumption or
a white-like exhaust smoke which cannot be
blamed on the oil-scraper rings on the piston,
replace the valve stem seals
1
, intended to pre
-
vent excess oil leakage.
It is recommended to replace them every time
the cylinder head is overhauled.
In order to replace them, use needle-nose pliers
to pull them out, being careful not to nick the
valve guide.
Once the valve stem seal is extracted, the lower
cup can be pulled out
2
.
3.17.5 CYLINDER HEAD: CHE-
CKING CYLINDER HEAD
BODY
Check the flatness between the head and cylin
-
der coupling surfaces.
This can be done using a rectified block and a
thickness gauge by positioning the block accor
-
ding to the directions shown in the figure.
The service limit is:
cylinder head flatness service limit: 0.05mm
Check that the state of use of the sliding zones
A
with the camshafts and
B
of the camshaft
support bearing housing are free of scratches
or signs of meshing.
Clean the oil passages for lubricating the cylin
-
der head by blowing compressed air into the
holes
C
,
D
and
E
.
1
C
B
A
E
D
2
