elizabethhayes•29d agoMost Upvoted

Found out 70% of engine failures come from coolant issues, not oil

I was reading through some warranty claims data from Cummins last week and that stat jumped out at me. We always stress about oil changes and fuel filters, but coolant chemistry is what kills these engines long term. Now I'm checking coolant samples on every mid-range rebuild I do. Has anyone else seen that pattern hold up in their shop?

2 comments

2 Comments

lilykelly29d ago

Wait, are you running coolant analysis on every rebuild now? I had the exact same wake up call about three years ago. Started pulling apart a fleet of Freightliners that were dropping like flies around 400k miles. The liners were all pitted to hell and the water pumps looked like they'd been through a war. Turns out nobody was testing the coolant, just topping it off with tap water when it got low lmao. Started doing quarterly coolant analysis and switched to a premix with the right SCA levels. Night and day difference. Now those same trucks are hitting 800k with original water pumps. The lab reports are honestly addictive to read, I love seeing the nitrite numbers actually hold steady.

henderson.vera28d ago

Yeah but hold on a second. I get what you're saying but I think we're overthinking this a bit. Not every rebuild needs a coolant analysis if you're doing the basics right. I've been running the same fleet of old Macks for over a decade and I just flush and refill with good old prestone green every 2 years. Never had a liner issue or a water pump failure. The lab reports are interesting but honestly for most shops that's just extra cost and time. Plus those premixes with the fancy SCA levels are expensive. If you're topping off with tap water then yeah you're asking for trouble but using distilled and the right coolant mix from the start solves the same problem without the quarterly testing. Maybe your Freightliners needed that extra care but not every truck is built the same.