Komatsu 170-3 Series, Shop Manual, Page: 413 / 454

170-3 SERIES
15-7
REPAIR AND REPLACEMENT OF PARTS
REPLACING VALVE SEAT INSERTS
a
When repairing without replacing the valve seat
insert (when there is surface roughness or
stepped wear), repair with the amount of sinking
of the valve is within the repair limit.
a
Machining drawings of new valve seat inserts is
shown in the right.
a
Checking for looseness of valve seat insert
Tap the outside of the valve insert of the cylinder
head with a hammer to check for any looseness
of the valve seat insert. If the valve seat insert is
loose or springs back, replace the insert.
1. Pulling out the valve seat insert
1) Using the grinder of valve e seat puller A1,
make grooves on the inserts to pull them out
according to the following procedure.
a
Set the air pressure to 490 – 588 kPa {5 to 6
kg/cm
2
}.
a
When replacing the grindstone of the grinder,
shut off the compressed air.
k
Before using the grinder, run it for one
minute to check abnormality.
a
After replacing the grindstone, run the
grinder for three minutes to test it.
k
Confirm that the grindstone is not dam-
aged, then install it to the shaft of the
grinder without applying excessive force.
Confirm that there is no play between the
grindstone and shaft.
k
When using the grinder, wear safety gog-
gles.
i) Install grindstone [5] to grinder [1].
ii) Install the sleeve and grinder after align-
ing the groove of sleeve [3] with holder
[2].
a
Adjust the position of the grinder with set
screw [4].
• Intake valve
• Exhaust valve
Item Intake valve Exhaust valve
Seat surface
angle (a)
30° 45°
Finish width (b) 3.5 mm 4 mm
Inside diameter
(c)
62 ± 0.05mm 60.4 ± 0.05mm
Inside diameter
(d)
– 53 mm
Seat surface
roughness
Max. 3.2 S
(7)
REPLACING VALVE SEAT INSERTS
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