TIL a lesson about old coolant hoses the hard way on a 2007 Civic

I had a customer come in with a slow drip from the lower radiator hose. It looked fine from the outside, no cracks or bulges. I gave it a squeeze and it felt firm, so I told him it was probably the clamp and sent him on his way. Two days later, he was back on a tow truck with the hose blown clean off and the engine overheated. When I cut the old hose open, the inside was completely rotten and flaky, like wet cardboard. The outside rubber was just a shell holding it together. The car had 140,000 miles and the coolant had never been flushed, which I found out later. Now I make a point to feel inside the hose end with a pick on any car over ten years old. Has anyone else been fooled by a hose that looked and felt solid but was rotten inside?

3 comments

3 Comments

the_hannah1mo ago

Yeah, that exact thing is why I don't trust the squeeze test anymore. The outside rubber can get hard and seem fine, but it's just a brittle shell. The real failure point is that inner liner rotting away from old, acidic coolant. On high-mileage cars, you gotta peel back the hose from the neck and actually look inside. If you see any black flakes or that wet cardboard look, it's already a dead hose walking.

chen.phoenix1mo ago

My buddy's truck did the same thing last month. Total mess.

the_river9d ago

black flakes or that wet cardboard look" - man, that's brutal. @chen.phoenix, I bet your buddy wished he'd known that before it grenaded on him. I've never actually peeled back a hose to check inside, but now I'm feeling like I should go stare at my engine bay with a flashlight for a while. The squeeze test has been my go-to for years, and I'm starting to realize it's probably let me down more than I know. Guess I'll be adding "cut open old hoses for science" to my weekend plans.