Crankshaft And Main Bearing; Crankshaft - Yanmar 3YM30 Sevice Manual

5. Inspection and servicing of basic engine parts

5.5 Crankshaft and main bearing

The crank pin and crank journal have been induction
hardened for superior durability, and the crankshaft is
provided with for balance weights for optional balance.
The crankshaft main veering is of the hanger type. The
upper metal (cylinder block side) is provided with an oil
groove. There is no oil groove on the lower metal
(bearing cap side). The veering cap (location cap) of the
flywheel side has a thrust metal which supports the
thrust load.

5.5.1 Crankshaft

(1) Color check after cleaning the crankshaft,
and replace the crank shaft if there is any
cracking or considerable damage.
(2) Bending of the crankshaft
Support the crankshaft with V-blocks at both ends of the
journals. Measure the deflection of the center journal
with a dial gauge while rotating the crankshaft to check
the extent of crankshaft bending. The total indicating
reading on the dial gauge is divided by two to obtain the
bend.
crankshaft
Crankshaft bend limit
Main bearing
metal (basic)
Thrust metal
Main bearing
cap (basic)
Main bearing bolt
mm
0.01
125
Balance weight
Crank shaft
(Inspection by color check)
Bend
Deflection
Dial gage
V-block
(Crankshaft bend measurement)
Crank shaft gear
Main bearing metal
(intermediate)
Main bearing cap
(intermediate)
Main bearing bolt
V-block