MTD P90 series Shop Manual page 113

Figure 11.5
Embedded abrasives
Figure 11.6
8. Because the oil suspends the particles, the engine
components that are immersed in oil will show defi-
nite signs of abrasive ingestion especially around the
connecting rod and main bearing journals.
See Figure 11.5.
NOTE: Abrasives that are trapped in the oil will cause the
lower portion of the combustion chamber to wear-
ing more than the upper portion.
NOTE: Wear of only one bearing surface on a new engine
could be a sign of a manufacturing defect.
NOTE: Abrasive particles can also be embedded into
materials that are softer than the abrasive. This will
cause the affected part to act like a piece of sand
paper or a grinding wheel. See Figure 11.6.
Failure Analysis
107