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My uncle told me to never trust a 'quick fix' on a coolant leak
He was a mechanic for over forty years in Detroit, and he always said if you see a stop-leak bottle in the system, plan on doing a full flush and finding the real problem. I brushed it off when a customer came in with a small leak and a bottle of that stuff already in there. I topped it up and sent them on their way. Sure enough, they were back two weeks later with the heater core completely clogged. The stop-leak had sealed the tiny leak but then traveled and gummed up the whole small passageway. It turned a fifty dollar hose job into a six hundred dollar dash pull. Now I check for it on every used car that comes in. Has anyone else had a simple additive cause a much bigger headache down the line?
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michael_bennett111mo ago
Gunk coated the sensor" is wild. I've seen that stuff plug heater cores and clog radiators but I never thought about it messing with a temp sensor. That would drive you nuts trying to diagnose. Cold starts running rich, weird fuel trims, no check engine light half the time. A tiny layer of that sealant sludge is enough to throw everything off. It's like the engine's lying to you about what temperature it's at.
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mason7283mo ago
Ever wonder if those sealants can mess with the coolant temp sensor? I had a car running lean because the gunk coated the sensor, making the computer think the engine was always cold. Spent a week chasing ghosts before we found the real problem.
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noah8803mo ago
Yeah chasing ghosts for a week sounds rough. Was it one of those stop-leak bottles or did it come from a previous repair with too much gasket maker? Trying to picture how much gunk it takes to actually insulate the sensor tip.
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