What Is That Goo? by Hernán Mercado-Corujo, P.E., CFEI, CVFI

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Clunking sounds, reduced engine power, wrecked hydraulic pumps--these are some of the symptoms of foreign substances making their way into an engine or transmission. Fuel and lubricants can become contaminated in several ways, including vandalism/fraud, inadvertent fluid mix-ups, and weather exposure, among others. If this happens on a piece of agricultural, industrial, or commercial equipment, the replacement and/or repair costs can be in the tens of thousands of dollars. For this reason, an inspection of the equipment along with the collection of substance samples may be worth the effort when analyzing, examining and assessing an engine or transmission failure claim.


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On a recent case, a tractor was found to have a failed transmission. Upon disassembly, a white substance was found within its hydraulic system. Samples were collected during the inspection and brought to the laboratory for further analysis. Fourier Transform Infrared Spectrometry (FT-IR) and Scanning Electron Microscope/Energy Dispersive Spectroscopy (SEM/EDS) techniques were used to analyze the substances.


A significant amount of moisture was present in the substance. The tractor sat out on a field for about a month. Weather data in the geographical area for that timeframe suggested the possibility of significant moisture in the air and the potential for it to condense at night inside the hydraulic system. Moisture could have entered the hydraulic system through the transmission breather valve or an exposed hose.

The FT-IR and SEM/EDS data showed that the white material was not an easily identified compound such as salt or sugar. SEM/EDS analysis revealed the potential presence of microorganisms on the sample. This suggested the development of a bacterial colony. Inorganic debris allowed for initial bacterial colonization sites, and the waste products of oil deterioration were manifested as the viscous, milky white substance found in the hydraulic system. Goo.

It is important to note that some manufacturers recommend that equipment such as this tractor be warmed up/idled periodically, perhaps to eliminate some of the problems that can arise due to prolonged periods of unused time.

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In the end, the analysis showed that the failure was not the result of an inherent product design. Had the owner followed proper preventive maintenance guidelines as instructed by the manufacturer, this failure would have most likely been avoided.

Contact Hernán Mercado-Corujo for more information.