Komatsu 4D98 Series Shop Manual page 74

4. Engine Body
@ Piston pin hole measurement
(mm)
@ Piston ring, ring groove and end clear-
ance measurement
l
Except for the top ring, to measure the
piston ring groove width, first measure
the width of the piston ring. Then insert
the piston ring into the rinig groove. In-
sert a thickness gage in between the
piston ring and groove to measure the
gap between them. Obtain the ring
groove width by adding ring width to the
measured side clearance.
l
To measure the end clearance, push
the piston ring into the sleeve using the
piston head, insert a thickness gage in
end clearance to measure. The ring
shall be pushed in to approx. 30 mm
above the bottom end of the cylinder.
For the top ring, measure only the pis-
ton ring joint end clearance in normal
state.
Measure at positions a and b
in directions A and B.
Piston pin hole
L-4
Ring components
Thickness
Measuring side clearance
J
4-26