Yanmar 4LHA-HTP Operation Manual page 346

Chapter 2 Basic Engine
6. Connecting Rod
6-2 Crank pin bushing
6-2.1 Checking crank pin bushing
Check for flaking, melting or seizure on the contact
surface.
6-2.2 Measuring crank pin oil clearance
Use a plastic gauge.
Procedure
(1) Use the press gauge (Plastigage) for measuring oil
clearance in the crank pin.
(2) Mount the connecting rod on the crank pin (tighten to
specified torque).
Connecting rod tightening torque
Apply engine oil to the thread and seat surface
(3) Remove the connecting rod and measure the broken
plastigauge with measuring scale. (Plastigauge)
Plastigage
Cylinder gauge
N'm(kgf-m)
113.1 ~ 122.9
( 1 1 . 5 - 1 2 . 5 )
2-26
6-2.3 Precautions for replacement of crank pin bushing
(1) Wash the crank pin bushing.
(2) Wash the large end cap, mount the crank pin bushing
and make sure that it fits tightly on the large end cap.
(3) When assembling the connecting rod, match up the
large end and large end cap number. Coat the bolts
with engine oil and gradually tighten them alternately
to the specified torque.
If a torque wrench is not available, make match marks
on the bolt heads and large end cap (to indicate the
proper torque position) and retighten the bolts to those
positions.
Alignment mark (Punched mark)
(4) Make sure there is no sand, metal cuttings or other
foreign matter in the lube oil. and that the crankshaft is
not scratched. Take special care in cleaning the oil holes.
t4LHA Series
Matching mark