12. Other/Driving System
186
Inspecting and Measuring
1. Visual inspection
EDX22190157
1) Visually inspect the pistons for wear, cracks or scratches,
and check the piston ring grooves with particular care.
2) Use a micrometer to measure the outside diameter of the
piston. Measure the piston 102 mm (4.0158 in.) above
the end of the piston head perpendicularly to the piston
pin as shown in the figure.
• Measure perpendicularly 100 mm (3.9370 in.) above the
end of the piston head
2. Cylinder bore I.D.
EH6OM043
1) Use a cylinder bore gauge to measure the inside diameter
of the cylinder liner. Measure three places at 45° inter-
vals: the top ring contact surface of the cylinder, the
middle, and the bottom of the oil ring contact surface. The
remainder after subtracting the maximum and minimum
values is the average value.
3. Clearance between the piston and cylinder liner
1) The clearance is the value of the cylinder liner I.D. minus
the piston O.D. If this result exceeds the allowable limit,
replace either the piston or cylinder liner depending on
which part is more worn.
4. Piston ring and piston ring groove
1) After disassembling the engine, check the piston ring for
wear and damage, and repair it with a new part if necessary.
5. Piston ring end clearance
EH6OM044
1) Measure the cut part of the snap ring.
2) Insert the piston ring perpendicularly into the top of the
cylinder.
3) Use a feeler gauge to measure the piston ring clearance.
4) If the measurement exceeds the limit, replace the ring.
6. Piston ring side gap
EDX22190081
Reference value
Ø127.833 ~ Ø127.847 mm
(Ø5.0328 ~ Ø5.0333 in.)
Reference value
Ø127.99 ~ Ø128.01 mm
(Ø5.0389 ~ Ø5.0398 in.)
Reference value
0.143 ~ 0.177 mm
(0.0056 ~ 0.0069 in.)
Reference value Allowable limit
Top ring
0.30 ~ 0.50 mm
(0.0118 ~ 0.0197in.)
1.5 mm
(0.059 in.)
Second ring
1.10 ~ 1.30 mm
(0.0433 ~ 0.0512 in.)
1.5 mm
(0.059 in.)
Oil ring
0.40 ~ 0.60 mm
(0.0157 ~ 0.0236 in.)
1.5 mm
(0.059 in.)
Feeler
gauge
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