Yanmar 6BY2 - Inspect Cylinder Block; Install Crankshaft

ENGINE
Cylinder Block and Crankshaft
5-62 BY Service Manual
© 2009 Yanmar Marine International
Inspect Cylinder Block
1. Remove all main bearing inserts. Ensure the
bearing seating surfaces are free of any debris.
2. Ensure that oil passages are clear and
unobstructed.
3. Check for discoloration or evidence of cracks. If
a fracture is suspected, use the color check
method or the MAGNAFLUX method to
determine if the cylinder block is fractured.
4. Measure cylinders for roundness, taper and
inspect for evidence of scoring. Consider
honing or replacing the cylinder block if the
measurements are not within specification.
5. Take measurements at three places
(Figure 5-114, (a, b, c)), and in two directions
(Figure 5-114, (d and e)) in each cylinder.
Figure 5-114
Figure 5-114
Cylinder Bore Specifications
Install Crankshaft
1. Select the correct bearing as follows:
(a) Locate and record the grinding size of
crankshaft (Figure 5-115).
Figure 5-115
Figure 5-115
(b) The crankshaft will be marked with yellow,
green or white paint to determine the correct
bearing shell to install in the bearing caps
(Figure 5-116).
Figure 5-116
Figure 5-116
Inspection Item
*
* Values are for new or reconditioned cylinders.
Specification
Bore Diameter stage 0
84.007 ±0.007 mm
(3.307352 ± 0.000276 in.)
Bore Diameter stage 1
84.257 ±0.007 mm
(3.317195 ± 0.000276 in.)
Permitted out of round of cylinder
bore
0.005 mm
(0.000197 in.)
Permitted conicity of cylinder
bore
0.01 mm
(0.000393 in.)
0000230B
a
b
c
d
e
20 mm
(0.75 in.)
20 mm
(0.75 in.)