Bubbles Everywhere: Cavitation and the Cooling System [E220]

Thanks to our Partner, Pico TechnologyWatch Full Video EpisodeMatt 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 coveredWhy 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/erosionShock wave effects (ties into why ultrasonic cleaning works)How bubbles form even in a pressurized cooling systemLocalized low-pressure zones behind an impeller bladePressure drops along surfaces and restrictions (design or contamination-caused)Why “radiator cap” is a misleading nameBetter term: degassing capIt maintains system pressure (key to preventing local boiling) and “burps” gas/vapor outCoolant chemistry isn’t just freeze/boil protectionThe inhibitor package forms a protective barrier on internal surfaces that absorbs cavitation attackOver time that protection depletes → cavitation damage shows upWater quality matters more than most people thinkMinerals/impurities can create deposits → restrictions → pressure drop zones → bubblesContamination can also become nucleation points for bubble formationDistilled/RO water or properly formulated premix is the safer play“Universal coolant” skepticismUse proper coolant type for the application—chemistry and inhibitor packages matterPractical takeaways for shopsStart treating cooling-system service as evidence-based preventionTesting and inspection that should be part of regular maintenance:Degassing cap pressure test (rated pressure matters)Coolant concentration (ideally with a refractometer/hydro refractometer)pH testing (imperfect, but can hint at inhibitor depletion)Voltage potential test with a DMM (if present, verify grounds and consider additive depletion as a possible indicator)Recommend coolant replacement based on:Test results you can measure + time/mileage intervals (what you can justify)Customer communication angle (the “why they should care”)A simple way to explain it without going full science-documentary:“Coolant doesn’t just prevent freezing and overheating—it protects the inside of the cooling system.”“Over time the protective chemistry wears out, and tiny vapor bubbles can collapse and pit metal surfaces.”“We’re restoring protection, verifying pressure control, and preventing long-term erosion.”Memorable moments / quotables“It’s not the bubble forming—it’s the collapse.”“We don’t think about cooling-system maintenance from an anti-cavitation point of view.”“We should stop calling it a radiator cap… it’s a degassing cap.”Thanks to our Partner, Pico TechnologyAre you chasing elusive automotive problems? Pico Technology empowers you to see what's really happening. Their PicoScope oscilloscopes transform your diagnostic capabilities. Pinpoint faults in sensors, wiring, and components with unmatched accuracy. Visit PicoAuto.com and revolutionize your diagnostics today!Contact InformationEmail Matt: [email protected] the Aftermarket A - Z YouTube ChannelSubscribe & Review: Loved this episode? Leave a 5-star review on Apple Podcasts and SpotifyThe Automotive Repair Podcast Network: https://automotiverepairpodcastnetwork.com/Remarkable Results Radio Podcast with Carm Capriotto: Advancing the Aftermarket by Facilitating Wisdom Through Story Telling and Open Discussion. https://remarkableresults.biz/Diagnosing the Aftermarket A to Z with Matt Fanslow: From Diagnostics to Metallica and Mental Health, Matt Fanslow is Lifting the Hood on Life. https://mattfanslow.captivate.fm/Business by the Numbers with Hunt Demarest: Understand the Numbers of Your Business with CPA Hunt Demarest. https://huntdemarest.captivate.fm/The Auto Repair Marketing Podcast with Kim and Brian Walker: Marketing Experts Brian & Kim Walker Work with Shop Owners to Take it to the Next Level. https://autorepairmarketing.captivate.fm/The Weekly Blitz with Chris Cotton: Weekly Inspiration with Business Coach Chris Cotton from AutoFix - Auto Shop Coaching. https://chriscotton.captivate.fm/Speak Up! Effective Communication with Craig O'Neill: Develop Interpersonal and Professional Communication Skills when Speaking to Audiences of Any Size. https://craigoneill.captivate.fm/