Komatsu 170-3 Series, Руководство по ремонту, Страница: 417 / 454

170-3 SERIES
15-11
REPAIR AND REPLACEMENT OF PARTS
5. Final check
a
Sinking and protrusion amount C of valve
(1): (sinking) 0.39
–
(protrusion) 0.21mm
a: Intake side
b: Exhaust side
d: Bottom surface of cylinder head
• Coat the seat surface of the new valve thinly
with red lead (minium), insert it in the valve
guide, push lightely against the valve insert
surface, and rotate 10
°
. Check the valve
insert contact surface, and confirm that the
contact is uniform without any breaks.
• or
Mark marks d (about 20 places)with a pencil
on the seal surface of the new valve as
shown in the diagram, insert it in the valve
guide, push lightly against the valve insert
surface, and rotate 10
°
. Check that the pencil
marks have been erased uniformly around
the whole circumference.
Airtightness testing with vacuum tester
• When carrying out an airtightness test with a
vacuum tester, test as follows
1) Wipe off all the dirt, dust, and oil from the
valve and valve seat surface with a cloth.
2) Assmble the valve, valve spring, retainer,
and cotter, tap the tip of the valve stem with a
plastic hammer 2 or 3 times directly from
above to bring it into tight contact with the
seat sutface.
3) Fit a vacuum cup that matches the size of
the valve in tight contact with the head sur-
face. When doing this, to improve the air-
tightness of the vacuum cup, coat grease on
the O-ring fitted to the vaccum cup, and fit it
in tight contact with the flat surface of the
head.
(Be careful not to get any grease on the seat
surface.)
4) Set the vacuum gauge to 93.3 kPa {700
mmHg}, and check that the pressure drops
less than 1.3 kPa {10 mmHg} in 3 seconds.
If it drops more than 1.3 kPa {10 mmHg} in 3
seconds, check for any dirt on the seat sur-
face, or rub the surface to correct it.
(7)
REPLACING VALVE SEAT INSERTS
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