Yanmar 1GM User Manual page 123

MULTICYLINDER ENGINES 117
0 11
ring--{ f
g.p
Expan sion
ring gap
6
3. Tighten the connecting rod cap to specification (Tab le
4). Do not rota te the crankshaft while the Plastigage is in
place .
4. Remove the connecting rod cap. To dete rmi ne bearing
clearance, compare the width of the flattened Plastigage
to the markings on the enve lope (Figure 42). If the clear-
ance is excessive, have the cra nkshaft reground and install
undersize bearings.
.....
;.~
Scale
~~~~~6/~~
_ Plastl gage
Connecting Rod Bearing
Clearance Measurement
I . Place the connecting rod and upper bearing half on the
connecting rod journal.
2. Cut a piece ofPlastigage the width ofthe bearing (F ig-
u re 40). Place the Plastigage on the journal, then install
the rod cap and bearing. Be sure to install the cap so the
marks on the cap and rod are on the same side (Figure 41).
Pisto n/Connecting Rod Installation
I . Rotate the crankshaft so the crankpin is at bottom dead
center.
2. Make sure the ring gaps are positioned as shown in
Figure 43 .
3. Immerse the entire piston in clean engine oil. Coat the
cylinder wall with oil.
4 . Install a p iston ring compressor on the piston around
the piston rings.
NOTE
Do not place Plastigage over the journal oil
hole.
CAUTION
Use extreme care in Step
5
to prevent the
connecting rod from nicking the crankshaft
journal.