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Chapter 6 INSPECTION AND REPAIR OF BASIC ENGINE
5.12 Main Bearing - Inspect
Inspect the sliding surface, back surface and end surface of
main bearing. If any defect such as local contact, sliding
scratches, corrosion and foreign material inclusion is found,
replace the main bearing with a new one.
Main Bearing - Inspect
5.13 Thickness of Main Bearing Shell - Measure
Measure the thickness of main bearing shell at its center.
If the value exceeds the limit, replace both upper and lower
main bearing shells with new ones as a set.
When the crankshaft is re-ground due to wear of crank jour-
nal, use the undersize bearing.
For the crankshaft grinding procedure, refer to "Crankpin
and Crank Journal - Grind" of "INSPECTION AND
REPAIR OF BASIC ENGINE."
Note: Replacement shells for undersized main bearing are
available in sizes of 0.25, 0.50, 0.75 and 1.00 mm
[0.0098, 0.0197, 0.0295 and 0.0394 in.]
Thickness of Main Bearing Shell - Measure
5.14 Thrust Plate - Inspect
Inspect the sliding surface, back surface and end surface of
thrust plate. If any defect such as local contact, sliding
scratches, corrosion and foreign material inclusion is found,
replace the thrust plate with a new one.
Thrust Plate - Inspect
Flaw, corrosion, peeling
End face
Measurement
at the center
of bearing
Item Size
Nominal
value
Standard value Limit value
Main bearing thickness at cen-
ter
Standard
3.500 mm
[0.1378 in.]
3.482 to 3.500 mm
[0.1370 to 0.1378 in.]
3.450 mm
[0.1358 in.]
Under size
0.25 mm
[0.0098 in.]
3.625 mm
[0.1427 in.]
3.607 to 3.625 mm
[0.1420 to 0.1427 in.]
3.575 mm
[0.1407 in.]
0.50 mm
[0.0197 in.]
3.750 mm
[0.1476 in.]
3.732 to 3.750 mm
[0.1469 to 0.1476 in.]
3.700 mm
[0.1457 in.]
0.75 mm
[0.0295 in.]
3.875 mm
[0.1526 in.]
3.857 to 3.875 mm
[0.1518 to 0.1526 in.]
3.825 mm
[0.1506 in.]
1.00 mm
[0.0394 in.]
4.000 mm
[0.1575 in.]
3.982 to 4.000 mm
[0.1568 to 0.1575 in.]
3.950 mm
[0.1555 in.]
Flaw, corrosion, peeling
End face
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