Cavitation - How Air Bubbles Destroy Diesel Engines
At Midway Diesel LLC in Eloy, AZ, our objective is to keep your diesel truck on the road, where it belongs. Whether it’s maintenance, repair, or information that keeps you from needing a repair, we do our best to keep you informed on how to best take care of your diesel truck. Cavitation is a leading killer of diesel engines. It’s an interesting process, albeit an expensive one if your diesel engine is a victim of cavitation. From our team here at Midway Diesel LLC, here's what you should look out for:
What is cavitation? - In this context, cavitation is the erosion of the side of the cylinder wall inside of a diesel engine. This is a problem that only engines with “wet sleeves” have - that is, cylinder sleeves that are in direct contact with engine coolant. On many diesel engines, coolant is able to flow around the cylinder sleeve, which greatly enhances the engine’s ability to stay cool. That’s a good thing but comes with its own set of problems. Cavitation occurs when the cylinder is eaten away from the coolant side, which can destroy an engine in a pretty short order.
How does cavitation work? - At first, it might seem surprising that cavitation is an issue at all. Essentially, cavitation is caused by air bubbles forming and then imploding on the side of the cylinder sleeve. When the engine is running, the sleeve is constantly vibrating - in some cases it vibrates more than others, depending on how loose the sleeve is in the engine. This vibration causes a disruption in the coolant around the sleeve, and what happens next sounds like a science experiment.
As the sleeve vibrates, it pulls away from and crashes into the coolant. It’s small scale but happens thousands of times very rapidly. During the pull-away phase of the vibration, the pressure is reduced where the coolant contacts the sleeve. This creates a lower boiling point in the coolant and allows tiny air bubbles to form on the sleeve. As the sleeve vibrates back into the coolant, it causes those bubbles to implode, ever so slightly eroding the coating on the side of the sleeve. Eventually, over the course of thousands and thousands of cycles, this protective liner is eaten away completely, and the metal itself begins to erode more quickly. This is where cavitation becomes a problem.
How does cavitation ruin an engine? - Once the cavitation reaches a certain point, a few issues may arise. The cylinder wall on the inside of the sleeve becomes weakened, allowing for collapse or damage during the combustion process. In many cases, the cavitation process eats all the way through the sleeve, allowing combustion pressure to enter the cooling system, and coolant to enter the cylinder. Either one of these is guaranteed to cause some problems, including total engine failure. Cavitation may damage the block itself, at the upper and lower points where the sleeve seals to the block. When this occurs, the coolant will make its way into the oil pan, where it will destroy bearings and other moving parts.
How do you prevent cavitation? - There are special additives that can be introduced into the cooling system to help stave off the effects of cavitation, and prevent it from happening in the first place. Checking and maintaining your coolant condition is also imperative to preventing cavitation.
How is a cavitation issue corrected? - Cavitation issues can be corrected by replacing the damaged sleeve, as long as it hasn’t escalated to the point where other components are damaged. Replacing a sleeve is a very invasive and time-consuming process, so we have to be sure nothing else has been damaged before proceeding with a sleeve replacement. If the sealing surfaces are damaged, or any internal damage has occurred as a result of coolant getting into space where it doesn’t belong, it’s often more cost and time effective to simply replace the engine. In situations where extensive damage has occurred, the repair alone is not a solution to the problem.
The best way to deal with cavitation is to prevent it from happening, but if a problem has already manifested, it’s important to deal with it appropriately. No matter your repair or maintenance needs, our professional diesel technicians have you covered. For the best diesel and fleet service shop in Eloy, AZ, call or stop by Midway Diesel LLC today.
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