In The Shop: Heat Defeats Thread-Locking Compound
Apr 27, 2011
Everybody calls it "Loctite," but that's technically a specific brand of thread-locking compound. Whatever you call it, it can be tricky removing bolts cemented in place with those products. The first trick is knowing they're cemented before you try to remove them. The second trick is to remove them.
There's really no way to know in advance if a bolt is cemented in place with thread-lock. I've learned to pay attention to a couple things that hint thread-lock has been used. If I start to remove a bolt or nut and notice a dry white powder coming out of the threads, there's a good chance thread-lock has been used. And if I get a whiff of a sweetish odor from that powder, that's a dead give-away that the nut or bolt was thread-locked. From then on I can use discretion in removing other bolts that might also be thread-locked.
Once I determine a nut or bolt has been cemented in place, it gives me the options of (a) strong-arming the fastener to see who is stronger--me or the thread-locking compound, or (b) applying a little heat to liquify the cement to ease removal. A little heat applied to the bolt and surrounding area can make cemented nuts and bolts come out as is they'd been lubricated.
Heat works great for fasteners cemented with medium-strength (blue-colored) thread-locking compound. High-strength locking compound--clear or red-colored--will usually liquify, but it may take more heat. There ARE thread-locking compounds on the market that are labeled as "permanent." While I'd certainly try heating them, good luck with removing any fastener cemented with those.
Which reminds me of when we were hauling my son's toolbox to the tech school for mechanics he attended. The instructor met us at the door, inspected every drawer before we could lug the toolbox into their classroom, and confiscated a couple tubes of thread-locking compound. When I asked why the inspection was necessary, he explained that a couple years earlier a smart-aleck graduating student had used "permanent" locking compound on every bolt and nut when he reassembled one of the school's motors as part of his final project before graduation. From that point on, thread-locking compounds had been banned from their classrooms.
