INSPECTION AND REPAIR OF BASIC ENGINE
6-17
4.9 Inspecting oil clearance of main bearing
(1)
Install the main bearing and the main bearing cap to the
crankcase. After tightening the main bearing cap with
the specified torque, measure the bearing inside
diameter.
Measuring main bearing inside diameter
(2)
Measure the crankshaft journal outside diameter.
Calculate the oil clearance of the main bearing by the
differential between the bearing inside diameter and the
journal outside diamter.
Measuring crank journal outside diameter
(3)
If the oil clearance exceed the limit, install the new
bearing and calculate the oil clearance again.
(4)
Even so it exceeds the limit, use undersize bearings.
(0.25, 0.50, 0.75 U.S) If an undersize bearing is used,
grind the crankpin to the specified undersize refer to the
following chart.
&$87,21
(a) When grinding the crankshaft journal, be sure to
grind the all journals to same size.
(b) Finish the fillet R to R3±0.2 mm [R0.1181±0.0079
in.] or less.
Width of crankshaft thrust bearing surface
Tightening torque:
83 ± 5 N·m
{8.5 ± 0.5 kgf·m}
[61 ± 3.6 lbf·ft]
Item
Nominal
Standard
Limit
Journal
outside diameter
(S.T.D)
ø 65 mm
[2.56 in.]
64.965 to 64.985 mm
[2.5577 to 2.5585 in.]
-
Oil clearance
-
0.035 to 0.085 mm
[0.0014 to 0.0033 in.]
0.200 mm
[0.0079 in.]
Measuring
directions
Measuring
locations
Item
Undersize
Finished size
Crankpin
undersize
0.25 mm
[0.0098 in.]
ø 64.75
-0.035
-0.015
mm
[2.5492
-0.0014
-0.0006
in.]
0.50 mm
[0.0197 in.]
ø 64.50
-0.035
-0.015
mm
[2.5394
-0.0014
-0.0006
in.]
0.75 mm
[0.0295 in.]
ø 64.25
-0.035
-0.015
mm
[2.5295
-0.0014
-0.0006
in.]
R3 ± 0.2 mm or less
[0.12 ± 0.008 in.]
R3 ± 0.2 mm or less
[0.12 ± 0.008 in.]
