Inspecting Oil Clearance Of Main Bearing - Mitsubishi S3Q2 Service Manual

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.
(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.
Item Nominal
Journal
ø 65 mm
outside diameter
[2.56 in.]
(S.T.D)
Oil clearance -
(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.
Item Undersize
0.25 mm
[0.0098 in.]
Crankpin 0.50 mm
undersize [0.0197 in.]
0.75 mm
[0.0295 in.]
(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.
Standard Limit
64.965 to 64.985 mm
-
[2.5577 to 2.5585 in.]
0.035 to 0.085 mm 0.200 mm
[0.0014 to 0.0033 in.] [0.0079 in.]
Finished size
-0.015
ø 64.75 mm
-0.035
-0.0006
[2.5492 in.]
-0.0014
-0.015
ø 64.50 mm
-0.035
-0.0006
[2.5394 in.]
-0.0014
-0.015
ø 64.25 mm
-0.035
-0.0006
[2.5295 in.]
-0.0014
INSPECTION AND REPAIR OF BASIC ENGINE
Tightening torque:
83 ± 5 N·m
{8.5 ± 0.5 kgf·m}
[61 ± 3.6 lbf·ft]
Measuring main bearing inside diameter
Measuring Measuring
directions locations
Measuring crank journal outside diameter
R3 ± 0.2 mm or less
[0.12 ± 0.008 in.]
Width of crankshaft thrust bearing surface
R3 ± 0.2 mm or less
[0.12 ± 0.008 in.]
6-17