That bolt won’t move, and if you keep reefing on it, it’ll break in two. Ugh.
It’s a problem more common than we care to admit. And worst of all, not only does it set the tone for the rest of the job at hand, but it’s also likely a bolt that threads into the engine block or other major component, making snapped hardware a headache of major proportions. Luckily, there are tricks to this trade, which a recent story on Hagerty Motorsports’ website tackled.
If you’re like us, a common first step for taking on stuck nuts and bolts is a hefty dousing of spray lube – but for that really persistent hardware, heat must eventually be applied. That’s where Hagerty’s Kyle Smith began his experiment, developing a test for heated extraction of a stuck bolt.
“Repeatability is a core tenet of any test,” Smith wrote in the story. “In each run, the bolt was torqued to 50 foot pounds with a dab of red Loctite on the threads and then left to cure for 10 hours—not a perfect duplication of a corroded fastener or something that has been torqued down for decades but a fair baseline for the methods we tested.”
The test involved a consistent weight applying torque to the bolt, with Smith then utilizing heat from five separate sources: flame via MAP-Pro, propane, butane, and an oxyacetylene torch, plus heat from an electric heat gun.
“Each heat source was applied to one side of the steel plate surrounding the bolt until the bolt broke free and the weight dropped,” Smith explained of the test. “The chief data point we were recording was time elapsed, but for the sake of more data (and an interesting talking point), I also measured the temperature of the steel plate and bolt right after each bolt broke free, using an infrared thermometer.”
Which worked best? To find that out, click the link below and read the story.
Photo by Kyle Smith / Hagerty Motorsports
