ENGINE MECHANICAL (M13 ENGINE) 6A2-71
Pistons, Piston Rings, Connecting Rods and
Cylinders Inspection
Cylinder
Visual inspection
Inspect cylinder walls for scratches, roughness or ridges which
indicate excessive wear. If cylinder bore is very rough or deeply
scratched or ridged, rebore cylinder and use oversize piston.
Cylinder bore diameter, taper and out-of-round
Using a cylinder gauge (1), measure cylinder bore in thrust and
axial directions at two positions (“a” and “b”) as shown in figure.
If any of the following conditions is noted, rebore cylinder.
1) Cylinder bore dia. exceeds limit.
2) Difference of measurements at two positions exceeds taper
limit.
3) Difference between thrust and axial measurements exceeds
out-of-round limit.
Cylinder bore diameter
Standard: 78.00 – 78.014 mm (3.0709 – 3.0714 in.)
Limit: 78.050 mm (3.073 in.)
Cylinder taper and out-of-round
Limit: 0.10 mm (0.004 in.)
Pistons
Visual inspection
Inspect piston for faults, cracks or other damaged.
Damaged or faulty piston should be replaced.
Piston diameter
As indicated in figure, piston diameter should be measured at a
position 19.5 mm (0.77 in.) from piston skirt end in the direction
perpendicular to piston pin.
Piston diameter specification
“a”: 50 mm (1.96 in.)
“b”: 100 mm (3.94 in.)
NOTE:
If any one of four cylinders has to be rebored, rebore all
four to the same next oversize. This is necessary for the
sake of uniformity and balance.
Standard size
77.953 – 77.968 mm
(3.0691 – 3.0696 in.)
Oversize
0.50 mm (0.0196 in.)
78.453 – 78.468 mm
(3.0887 – 3.0892 in.)
“a”: 19.5 mm (0.77 in.)
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