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Thought I'd try that old trick with a heat gun on a stubborn O-ring seal
Working on a Cessna 172's fuel selector valve, the O-ring was stuck in its groove like it was glued. I've heard guys say a little heat can help, so I grabbed my heat gun on low and gave it about 30 seconds of gentle warming. Instead of loosening up, the O-ring got even more stuck and started to look a bit shiny, like it was starting to cook. I shut it off right away. Learned that even low heat can mess with the material way faster than you think, especially on older rubber. Had to carefully pick it out with a dental pick, which took forever. Now I just use a proper O-ring pick tool and some silicone spray, no shortcuts. Anyone got a better method for those really baked-on seals without risking damage?
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susan1301mo ago
Actually, that heat gun trick works fine if you do it right. You probably just used too much heat or held it too close. A quick blast from further away can soften old rubber without cooking it. Sometimes those old-school methods are the best tools we have. Your bad experience doesn't mean the method is wrong, just that it needs a careful hand.
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elliot_barnes21d ago
I've seen three different people ruin perfectly good gaskets with that heat gun method, and two of them were seasoned mechanics. @susan130, I get that it worked for you maybe once or twice, but calling it a solid trick ignores how much risk is involved. A heat gun blasts 800 to 1000 degrees, and if your hand slips even a little or you drift off the focus zone, you're welding rubber to metal for good. In my experience, the margin for error is way too small for most people, and the old-school way I'd trust is patience with penetrating oil over a few days. Your mileage may vary, but I see more seals ruined than saved with that approach.
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