1D-51 Power Unit Mechanical:
Cylinder Bore
Inspect cylinder walls for scratches, roughness, or ridges
which indicate excessive wear.
If cylinder bore is very rough, deeply scratched or ridged,
bore cylinder and use oversize piston.
Cylinder Bore Wear (Difference)
Using telescoping gauge (1), measure cylinder bore in
both axial (vertical line, following crankshaft) and
transverse (horizontal line across crankshaft) directions
at two positions as shown in figure.
NOTE
Purchase a commercially available
telescoping gauge for this measurement.
Check the following:
• Difference between measurements at the two
positions (taper).
• Difference between axial and transverse
measurement (out-of-round).
If measurement exceeds service limit, bore or replace
cylinder.
Cylinder bore wear (difference)
Service limit: 0.10 mm (0.039 in.)
Piston to Cylinder Clearance
1) Measure the piston diameter at a point 13 mm
(0.512 in.) above the piston skirt at a right angle to
the piston pin bore.
Special tool
(A): 09900–20203 (Micrometer (50 – 75
mm))
Piston skirt diameter
Standard: 74.970 – 74.990 mm (2.9516 – 2.9524
in.)
2) Measure the cylinder bore at 50 mm (1.969 in.)
below the cylinder head gasket surface at a right
angle to the crankshaft pin.
NOTE
Purchase a commercially available
telescoping gauge (1) for this measurement.
Cylinder bore diameter
Standard: 75.000 – 75.020 mm (2.9528 – 2.9535
in.)
3) Calculate the piston / cylinder clearance (Clearance
equals difference between piston diameter and
cylinder bore measurements).
If clearance exceeds service limit, replace piston
and/or cylinder or bore cylinder.
Piston to cylinder clearance
Standard: 0.020 – 0.040 mm (0.0008 – 0.0016 in.)
Service limit: 0.100 mm (0.0039 in.)
“a”: 50 mm (1.96 in) “b”: 90 mm (3.54 in)
I9J011140247-01
“a”
“b”
I9J011140060-01
“a”: 13 mm
“a”
(A)
I9J011140061-02
50 mm
I9J011140248-02
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