Measuring Clearance Between Main Bearing And Crankshaft Journal - Mitsubishi Heavy Industries SL Series Service Manual

INSPECTION AND REPAIR OF BASIC ENGINE
4.9 Measuring clearance between main bear-
ing and crankshaft journal
(a) When grinding crank journals, be sure to grind all
the journals to the same size.
(b) Finish the fillet radius to the specified dimension.
(1) Reassemble main bearings.
(2) Tighten the main bearing caps to the specified torque.
(3) Measure the inside diameter of the main bearings.
(4) Measure the outside diameter of the crank journal.
(5) Calculate the clearance between the inside diameter of
the main bearing and outside diameter of the crank
journal.
(6) Replace the main bearing if the clearance exceeds the
limit.
(7) Measure the clearance between the main bearing cap
and the crank journal again. Use the undersize bearing
if the limit is exceeded.
(8) If an undersize bearing is used, grind the crank journal
to the specified undersize.
Nomi-
Item
nal
Outside diameter ø 52 mm
of journal (S.T.D) [2.05 in.]
Oil clearance -
Item Undersize
0.25 mm
[0.0098 in.]
Crankpin 0.50 mm
undersize [0.0197 in.]
0.75 mm
[0.0295 in.]
6-16
Standard Limit
51.985 to 52.000 mm
-
[2.0466 to 2.0472 in.]
0.030 to 0.077 mm 0.100 mm
[0.0012 to 0.0030 in.] [0.0039 in.]
Finish dimension
0
ø 51.75 mm
-0.015
0
[2.0374 in.]
-0.0006
0
ø 51.50 mm
-0.015
0
[2.0276 in.]
-0.0006
0
ø 51.25 mm
-0.015
0
[2.0177 in.]
-0.0006
49.0 to 53.9 N·m
Measuring
{5.0 to 5.5 kgf·m}
directions
[36.2 to 39.8 lbf·ft]
Measuring
points
Measuring main bearing fitting bore
Measuring
Measuring
directions
points
Measuring crank journal outside diameter
R2 mm
[0.08 in.]
Width of crankshaft thrust bearing surface
R2 mm
[0.08 in.]