Mercury MerCruiser Service Manual page 218

Engine Inspection and Assembly
Due to loading factors, the lower half of a crankshaft bearing set will generally exhibit the most wear. If inspection indicates the
lower bearing half is suitable for reuse, it can be assumed that the upper bearing half can also be reused. If the lower bearing
half shows evidence of wear or damage, replace the entire bearing set. Never replace one half of a bearing set without
replacing the other half.
a
Main bearing failure example
a - Contamination scratches
b - Contamination particles
c - Tapered journal
d - Oil starvation
e - Radius ride
f - Improper seating
g - Fatigue failure
Page 3B-16
b
d
f
© 2016 Mercury Marine
c
e
g
90-8M0099748 eng DECEMBER 2015
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