Yanmar 4BY, Service Manual

Page: 119 / 275

ENGINE
5-64
BY Service Manual
Cylinder Block and Crankshaft
Figure 5-108
6. Compare the width of the flattened
PLASTIGAGE to the graduation marks on the
package
(Figure 5-108, (1)) . The mark that
most closely matches the width of the flattened
PLASTIGAGE will indicate the bearing oil
clearance.
Main Bearings
Figure 5-109
1 – Crankshaft
2 – Oil Clearance
3 – Bearing Inserts: yellow, green, white
4 – Bearing Cap
• Ge = Yellow
• Gn = Green
• Ws = White
Connecting Rod Bearings
Figure 5-110
1 – Crankshaft
2 – Oil Clearance
3 – Bearing Inserts: red or blue
4 – Bearing Cap
• Rt = Red
• Bl = Blue
7. Figure 5-109 and Figure 5-110 show the
relationship of each color coding compared to
diameter. If necessary, install bearing inserts
having a different color coding.
8. Repeat with the remaining bearings.
Inspection of Crankshaft
1. Use the color check method or MAGNAFLUX to
inspect the crankshaft for cracks. Replace the
crankshaft if evidence of fractures are found.
2. Measure the outside diameter of each crankpin
and main bearing journal. Take measurements
at several places around each bearing surface.
If not within specification, grind the journals and
install undersize bearings, or replace the
crankshaft.