considered a trendline. Cause for concern should only occur when significant
deviations in the established trendline are present.
While trendline analysis on wear metals can prove informative and useful, a
transmission removal decision should not be based solely upon the analysis. A
removal based solely on wear metal analysis may result in an unnecessary tear
down. The results should be used in conjunction with other inspection procedures
such as functional check, road test, or fluid sump/internal filter inspection.
Transmission removal should occur only if the additional investigation warrants
it.
c. Water/Engine Coolant Contaminant.
NOTE: Cooler water can be contaminated by engine oil. Be sure to
locate the actual source of cooler contamination.
The presence of water and/or ethylene glycol coolant mixture in the transmission
fluid is detrimental to the reliability and durability of the internal components
because it has a deteriorating effect on the transmission components. Frictional
capacity of drive clutch plates can be greatly reduced as a result of surface film or
impregnation and the presence of glycol will physically deteriorate clutch plate
materials.
If contamination is suspected, obtain a fluid sample when transmission fluid is at
normal operating temperature to be sure a contaminant, if present, is thoroughly
dispersed in the fluid being sampled. The analysis of the sample, by the fluid
supplier or any qualified laboratory, will provide the degree of contamination and
possibly a clue as to its source. A minimal amount of water and glycol may be
due to one or all of the following:
• Uncovered oil drums
• Open transmission fill tube
• Glycol from an all-purpose fill container
• Defective transmission oil cooler.
Do not use fluid contaminated by water, regardless of whether it contains glycol,
if the water is greater than 0.2 percent by volume of fluid.
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