D439E Service Manual 2. Engine Mechanical System (D439E)
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3. Check the cylinder wall to see if it is cracked or
damaged. If it is abnormal, repair (oversize) or
replace the cylinder sleeve.
4. Measure the cylinder sleeve ID using the cylinder
gauge. If it is excessively worn, repair it with
oversize and replace the piston and piston ring.
Clearance between piston and cylinder sleeve :
0.080 ~ 0.130 mm
CAUTION
1. When replacing piston, piston ring should be
replaced together.
2. Even if only one cylinder needs boring, all
cylinder walls should be grinded with over
size at the same time
3. Measure the most seriously worn cylinder wall
and select the oversize based on the
measurement.
4. Available over sizes are +0.25, +0.50, +0.75
and +1.00.
5. Piston and connection rod should be replaced
with the new one which has identical weight
and grade with the old one.
a. Measure the inner diameter of cylinder sleeve
using the cylinder gauge (1).
Inner diameter of cylinder sleeve : 104.00 ~
104.03mm
b. Measure the outer diameter of piston skirt at
the position, which is 85 mm down from the
upper piston.
Outer diameter of piston : 103.91 ~ 103.92 mm
Piston
1. Check each piston to see whether it is damaged.
2. Check whether the piston pin (1) is installed
correctly in the piston hole.
If any defect is found, replace the piston and
piston pin as an assembly.
Piston pin should slide into the piston hole
smoothly when it is pushed y hand.
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