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| Normal wear
exhibits "Smooth" finish. Accelerated wear may be caused by fine abrasives
left in from extended oil change intervals not monitored by analysis. |
Bearing surfaces which
reveal scratches or "Trenches" are typical of particle wear. The oil
filter element should reveal the culprit. |
Particles, sandwiched between
bearing and bore, can create distortion and a "Hot Spot". Particle may be
embedded and visible. (see arrow) |
"Oil Starvation" can
be attribued to a number of causes. Wiping, Blue Discoloration and
"Adhesion" wear to shaft or pin are common indicators. |
Water and/or
antifreeze in the engine oil create milky, grey edging and possible black
corrosion on the lining. Pitting and Flaking are progressive
damage. |
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| Worn, Pitted
surfaces with dark green coloration, indicate fuel dilution of lube oil.
This corrosive action may also pit crankshaft. |
"Shiny" indicators on the
back of the bearing insert are signs of movement. Bore Geometry and
surface dimension must be checked. |
This is "Cavitation
Erosion", on the unloaded half of insert. "Entrained" air bubbles in oil
may cause additional lubrication problems. |
Cavitation Erosion
(round flaked portion) caused by entrained air bubbles, along with
embedded hard debris, can require a close examination for failure
analysis. |
Lack of lubrication can be
attributed to engine oil dilution, breakdown or elevataed temperature.
Causes must be investigated, too prevent further occurences. |
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| "Cold Start" can
destroy bearing surfaces and lead to progressive failure. "Cold Start"
failure is caused by lack of lubrication and running up to full RMP before
the engine is warm. |
"One Sided" wear is
usually a misaligned or improperly adjusted assembly. Damage to adjacent
bearings may occur. |
Localized, symmetrical
wear about a journal's axis is due to deviations in the journal's
geometry. |
Localized wear on opposite
sides of a pair's shell halves is normally caused by a bent connecting
rod. |
Bearings improperly
"Located" during installation can sometimes be hard to spot. |
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| "Offside" wear
is usually an indication of misaligned crankshaft or bore. This may not
apply to "Offside" connecting rods. |
Localized wear on main
bearings showing a pattern along the shaft, for example, worst wear on the
middle bearings, is evidence of a bent crankshaft. |
This indicator may be
evidence of "loose" or "tight" fit. This bearing experienced excessive
"crush", causing deformation in this area. |
Loccalized, polished areas
are on steel back (fretting); caused by improper crush or movement of
insert within its respective bore. This may cause damage to housing and/or
shaft. |
Excessive "End Play" can
rapidly wear thrust washers. This can be caused by "abrupt" engagement or
"riding the clutch". |
