Yanmar 3JH4E, Руководство по обслуживанию

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5. Inspection and servicing of basic engine parts
178
5.1.5
Cylinder bore
measurement
Especially clean head surface, cylinder bores and
oil holes, and check the below items after
removing any carbon deposit and bonding agent.
(a) Appearance inspection
Check if there is any discoloration or crack. If
crack is suspected, perform color check.
Sufficiently clean the oil holes and check they
are not clogged.
(b) Cylinder bore and distortion
Measure at 20 mm below the crest of the liner,
at 20 mm from the bottom end and at the
center in two directions A and B as shown in
the below figure.
Roundness:
Roundness is found as follows though it is the
simple method. Measure cylinder diameters
of the A direction and the B direction on each
section of a, b and c.
Roundness is the maximum value among
those difference values.
Cylindricity:
Cylindricity is found as follows though it is the
simple method.
Measure cylinder diameters of a, b and c
sections in the A direction, and calculate the
difference in maximum value and minimum
value of the measured diameters.
In the same way measure and calculate the
difference in the B direction.
Cylindricity is the maximum value between
those difference values.
mm
Item Standard Limit
Cylinder bore
diameter
3/4JH4E 88.000~88.030 88.200
4JH4-TE
4JH4-HTE
84.000~84.030 84.200
Cylinder roundness/ Inclination 0.01 or less 0.03
010387-00X
20 mm
A
B
Measure in two directions
A and B at points a, b and c.
a
b
c
20 mm
001495-01E