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Bubbles Everywhere: Cavitation and the Cooling System [E220]
Description
Thanks to our Partner, Pico Technology
Matt goes down a rabbit hole on the science of bubbles and comes back with something surprisingly practical: cavitation is a major source of cooling-system component damage, especially in and around water pumps. The “bad guy” isn’t the bubble forming—it’s the bubble collapsing, releasing intense localized energy, micro-jetting, and shock waves that pit and erode metal surfaces over time. The takeaway: approach cooling-system maintenance as anti-cavitation prevention, not just “keep it from overheating.”
Key topics covered
Why cavitation damage is often misattributed to electrolysis (and what’s actually happening)
The real destruction mechanism:
- Bubble collapse → extreme localized heat (doesn’t “cook” the system, but signals energy density)
- Micro-jet stream through the collapsing bubble “donut” → pitting/erosion
- Shock wave effects (ties into why ultrasonic cleaning works)
How bubbles form even in a pressurized cooling system
- Localized low-pressure zones behind an impeller blade
- Pressure drops along surfaces and restrictions (design or contamination-caused)
Why “radiator cap” is a misleading name
- Better term: degassing cap
- It maintains system pressure (key to preventing local boiling) and “burps” gas/vapor out
Coolant chemistry isn’t just freeze/boil protection
- The inhibitor package forms a protective barrier on internal surfaces that absorbs cavitation attack
- Over time that protection depletes → cavitation damage shows up
Water quality matters more than most people think
- Minerals/impurities can create deposits → restrictions → pressure drop zones → bubbles
- Contamination can also become nucleation points for bubble formation
- Distilled/RO water or properly formulated premix is the safer play
“Universal coolant” skepticism
- Use proper coolant type for the application—chemistry and inhibitor packages matter
Practical takeaways for shops
Start treating cooling-system service as evidence-based prevention
Testing and inspection that should be part of regular maintenance:
- Degassing cap pressure test (rated pressure matters)
- Coolant concentration (ideally with a refractometer/hydro refractometer)
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