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3-40 DISASSEMBLY, REASSEMBLY, INSPECTION, AND MAINTENANCE
Piston and Connecting Rod
•
Using an inside micrometer, measure the pin hole bore of the piston
in several places.
Piston Pin Hole Bore Service Limit (maximum)
FE120: 14.033 mm (0.5525 in)
FE170: 16.033 mm (0.6312 in)
FE250: 18.033 mm (0.7100 in)
FE290: 19.033 mm (0.7493 in)
FE350, 400: 20.033 mm (0.7890 in)
If the measured value is greater than the service limit, replace the
piston with a new one.
Piston Pin Inspection
•
Using a micrometer, measure the piston pin diameter in several
places.
Piston Pin Diameter Service Limit (minimum)
FE120: 13.975 mm (0.5502 in)
FE170: 15.975 mm (0.6290 in)
FE250: 17.975 mm (0.7077 in)
FE290: 18.975 mm (0.7470 in)
FE350, 400: 19.975 mm (0.7864 in)
If the measured value is smaller than the service limit, replace the
piston pin with a new one.
A: Piston Pin
Piston Ring Inspection
•
Using a micrometer, measure the thickness of the piston ring in
several places.
Piston Ring Thickness Service Limit (minimum)
- for both Top and Second Rings
FE120, 170: 1.42 mm (0.056 in)
FE250, 290, 350, 400: 1.44 mm (0.057 in)
If the measured value is smaller than the service limit, replace the
piston rings as a set.
•
Fit the piston ring inside the cylinder, and use the top of the piston to
insert the piston ring perpendicularly to the skirt area at the bottom
of the cylinder. Then, use a gap gauge to measure the clearance of
the ring gap.
Piston Ring Gap Clearance Service Limit (maximum)
Top Ring Second Ring
FE120, 170: 1.0 mm (0.039 in) 1.0 mm (0.039 in)
FE290, 350, 400: 1.2 mm (0.047 in) 1.2 mm (0.047 in)
If the measured value is greater than the service limit, replace the
piston rings as a set. (This is because of the difficulty in properly
measuring the oil ring.)
A: Piston Ring
B: Ring Gap Clearance