By John Smith
It almost defies logic that a mighty diesel engine could be destroyed by something as fleeting and fragile as a bubble. But when that bubble is in coolant and it is formed in the cylinder liner, over time, the results can be devastating. It is called cavitation corrosion and it represents one of the reasons that today’s coolant formulas are so important.
The cavitation challenge can be traced to the combustion process, where the pounding motion of a piston will cause a cylinder to vibrate, generating bubbles in the coolant that flows around the cylinder liner. These bubbles can implode against the liner with enough force to pit the metal, eventually chewing their way into the combustion chamber.
Effective chemistry in today’s extended-life coolants (ELC) – including nitrites or nitrite-molybdates – can attack the specific location of any weakness in the cylinder liner’s protective coating.
“There still is a prevalent amount of conventional coolant out there,” according to Carmen Ulabarro, direct channel manager, Chevron Products. But the ELC products are approaching 50 percent of the marketplace, if they have not reached that point already, she says. That is due in no small part to the fact that the reservoirs in new trucks are filled with the advanced chemistry as soon as equipment rolls off the assembly line.
The trucking industry was introduced to these formulas in 1996, shortly after General Motors introduced the Dexcool extended-life coolants, which marked the beginning of the end for annual flush and fills in the automotive world. Caterpillar responded by releasing the standards for an ELC that could be used in a heavy-duty application.
That introduced a fundamental shift in the chemistry that could be poured into a reservoir.
