A company located on the west coast operates a fleet of several hundred long-haul trucks. Oil analysis is a valuable tool used to understand oil condition, contamination and potential part failure due to wear. This company used oil analysis for diagnostic purposes as well as helping identify the reasons why parts would fail prematurely. Often the oil analysis results would drive work orders on engines and transmissions.
A newly appointed maintenance manager began to dig deep into the oil analysis results and became alarmed when he witnessed high levels of copper on a few assets with only several hundred hours on the engine and oil. The diagnostic commentary indicated that the copper levels were within acceptable ranges for the time on the engine and oil yet the maintenance manager was still skeptical. He ordered the trucks to be taken off the road and inspection to take place. After inspection it was determined that the engines were in excellent condition. His fears were based on an experience he had while being a mechanic. A past oil analysis report indicated high copper levels and the report was ignored. In most cases, a coolant leak into the crankcase oil will bring a detectable and often sizeable concentration of copper. In new oils, high copper levels can occur due to copper reacting with the sulfur found in ZDDP which is a very typical anti-wear compound in engine oil. For new engines with less than 1,500 hours of service life, the copper on the cooler core reacts with the Sulphur, resulting in copper sulfides forming on the copper cooler tubes. This new compound is found in the oil, contributing to a rising copper concentration than can reach well over 300 ppm. The copper sulfide is harmless and typically not associated with a cooler failure, accelerated wear or lubricant oxidation. In the case of a coolant leak, other metals will appear from additives that are formulated with the glycol or introduced as a supplement into the coolant. These elements could be sodium, silicon, potassium, molybdenum and boron. A proper practice is to establish a baseline of the asset and understand the chemistry of the antifreeze to determine the normal family of elements found in its formulation. When the same relative concentrations of elements, along with copper, are found in the used engine oil, one should rightfully suspect a coolant leak.
When the trucks were brought off line due to an assumption and lack of confidence in the diagnosis, the cost of the labor was $1,000. The lost logistic production revenue was $9,000. While the spirit of the manager was appreciated, the assumption was a costly learning example. After the incident, the newly appointed maintenance manager gained confidence in the diagnosis and has since been able to utilize his skills to help drive down the overall costs of failure.
ALS is the global leader in oil analysis and can help in establishing a reliability centered maintenance practice at your facility. Contact your local ALS lab for more details.
Michael D. Holloway MLT1, OMA1, MLA1, CLS
Manager – Strategic Accounts and External Training, Tribology