How to remove stuck fasteners, part 1: Loosen without breaking

This week we begin a series on something quite familiar to vintage car owners—dealing with stuck fasteners.

Those of us of a certain age fondly remember Robert Pirsig’s now-classic tome Zen and the Art of Motorcycle Maintenance. I particularly recalled the chapter on “Stuckness,” and how he hinged dealing with stuckness on the metaphysics of quality, which was a major theme of the book. Years later, I circled back to see what Mr. Pirsig had actually said about how to remove stuck fasteners.

“What your actual solution is is unimportant, as long as it has quality. Thoughts about the screw as combined rigidness and adhesiveness, and about its special helical interlock, might lead naturally to solutions of impaction and use of solvents. That is one kind of quality track. Another track may be to go to the library and look through a catalog of mechanic’s tools, in which you might come across a screw extractor that would do the job. Or to call a friend who knows something about mechanical work. Or just to drill the screw out, or just burn it out with a torch. Or you might just, as a result of your meditative attention to the screw, come up with some new way of extracting it that has never been thought of before and that beats all the rest and is patentable and makes you a millionaire five years from now. There’s no predicting what’s on that quality track. The solutions all are simple … after you have arrived at them. But they’re simple only when you know already what they are.”

Yeah… so, not very helpful. I regarded it as an entrée to providing some specific and hopefully useful tips on how to remove stuck fasteners, rather than hoping you can think them free.

Let me begin by saying that if you have a set of those “Easy Outs,” the reverse-threaded cone-shaped spiral bits you’re supposed to insert into a hole you’ve drilled through a stuck bolt, the best advice I can give you is go to your tool box, find every one of them, and throw them in the garbage. My experience is that if a bolt is so stuck that you snapped its head off trying to get it out, an Easy Out is highly unlikely to turn the tide, much less the bolt, and is very likely to snap off in the hole. And if it does that, you are, shall we say, screwed.

In general, stuckness should be approached with something of a mechanic’s Hippocratic Oath: First, do no harm. Start off with the least invasive procedure, moving up in complexity in small steps and force as required. The jokes about throwing the Easy Outs in the garbage notwithstanding, you would only foolishly attempt to use them once you’d already rounded the head off a bolt or snapped it clean off, and the goal is not to reach that point.

The double-edged sword of leverage

One issue is that leverage is both the solution and the problem. Archimedes reportedly said, “Give me a long enough lever and a place to stand, and I shall move the world.” If you have a high-quality set of six-sided sockets, and you put a pipe on the end of a breaker bar, it’s not difficult to generate sufficient leverage that you either break the bolt loose, or literally break the bolt. If you hear that reassuring crack followed by EEEeeeeeee, then you broke the bolt loose. But if instead you hear nothing when it starts to turn, odds are the bolt is in the act of having its head twisted off, and in about a quarter of a second you’ll experience that sickening sensation of knowing that you have several unanticipated hours of hard physical labor ahead of you.

Now, there are times when you may want to simply twist the heads off bolts. Where rusty nuts and bolts connect two exhaust flanges, for example, and there’s space between the flanges, I’ll sometimes try to snap them, as often it’s less work than cutting them. The issue is knowing in advance how much hurt you’re going to be in if you unintentionally snap a bolt or round a nut. With experience, you develop a good sense of whether to put a four foot pipe on the end of a breaker bar and go for it, or whether to stop and seek other solutions (e.g., heat).

The role of air tools

If you own a set of air tools, you probably already know the truth of the following statement many regard as sacrilege: Air tools are not for removing incredibly tight nuts; they’re for removing normally-tight nuts incredibly quickly. If you need to zip off the big nut in the middle of a front strut bushing, or the dozen Allen key bolts holding on a half axle, air tools are so good that it’s almost cheating. But if you have some stubborn nut on, say, a stud holding the headpipe to the exhaust manifold, it may simply sneer at your impact wrench. At times, believe it or not, this is actually a good thing. While an impact wrench probably will deliver sufficient torque to twist the head off a small 10mm bolt if you just let it do its whacketa whacketa whacketa thing on it over and over, it is unlikely to twist the head off a 17mm or a 19mm bolt. In contrast, you totally can twist the head off a bolt that size with a four-foot pipe on a breaker bar.

The classic cheater bar on the end of a breaker bar. It can break your nut free, or it can, uh, break your nut.
The classic cheater bar on the end of a breaker bar. It can break your nut free, or it can, uh, break your nut. Rob Siegel

Soak it

The first line of attack with stuck nuts or bolts is to use penetrating oil. Do not use WD40! WD40 is not penetrating oil! It won’t hurt anything, but neither will it penetrate or free anything. In the automotive world, the best-known penetrating oil is probably PB Blaster, which has the advantage that it’s sold in most any auto parts store. I far prefer a product by Kano Laboratories called SiliKroil, or its brother, AeroKroil. They both do an astonishingly good job of creeping into rusty threads and helping to free them up. They are both available on Amazon (what isn’t?). Note that you can find online articles where these and other penetrating oils are tested, and where the winner is a home-brewed 50/50 mix of acetone and automatic transmission fluid. So use whatever you have had success with.

There are a number of good penetrating oils. I like AeroKroil from Kano.
There are a number of good penetrating oils. I like AeroKroil from Kano. Rob Siegel

I’ll typically give a stuck fastener a good soaking in Kroil, wait a couple of minutes, and then hit it with the impact wrench. If it comes off, great. If not, there’s the temptation to put the cheater bar on the end of the breaker bar and trying to get more leverage than the impact wrench will generate. As I said above, maybe this is a good idea, and maybe it’s not; it all depends on what the, ahem, impact is if you happen to snap the bolt. If that impact is minimal, I may go for leverage, but if I know that I’ll cry if the bolt snaps, then I go for heat.

Heat it, heat it good

For many years I heard folks extol the virtues of heat as a panacea for stuck fasteners, and for many years I dutifully put a propane torch on stuck nuts and had them laugh at it. I now know why. A propane torch simply doesn’t get a fastener hot enough to help break the bond of corrosion.

What you need, at a minimum, is MAPP gas. You can look the composition of MAPP gas up on Wikipedia, but the take-away message is that it gets hotter than propane, but not as hot as an oxy-acetylene torch. It’s not going to melt a fastener, but it can get it glowing. MAPP gas also has an advantage over oxy-acetylene that it’s much easier to use: It comes in a single bottle, it lights like propane, and there’s no adjustment of the flame as is required with oxy-acetylene.

Obviously, when you use any torch, have a fire extinguisher at the ready and don’t wear any loose flammable clothing. Work the torch around the fastener for 30 seconds to a minute to get it nice and hot from all sides. Wait a minute or two. Then, using extreme care not to burn yourself, put some torque on the fastener, either with an impact wrench or with a breaker bar (be very careful that the heat doesn’t travel from the fastener up the breaker bar and burn your hand), and see how you do. Repeated applications of heat are often necessary to break loose a really stubborn nut.

Don’t even try propane. Go straight to MAPP gas.
Don’t even try propane. Go straight to MAPP gas. Rob Siegel

If MAPP gas isn’t enough—and it often isn’t—I combine it with a Goodson’s Oil Galley Wax Stick. These are available on Amazon or directly from Goodson. A friend of mine, who is a pro and spends a lot of time working on other people’s rusty old British metal, turned me onto them and I have to admit that they are the cat’s meow. Other folks say that a beeswax candle works just as well. Perhaps it does. All I know is that these things routinely save my bacon.

Get the fastener glowing red hot with the MAPP gas torch, walk the end of a Goodson’s wax stick around the circumference of the threads (don’t let the hot wax drip on your hand), wait a minute for the wax to get drawn in, put some torque on the fastener (taking extreme care because it was, you know, glowing red a minute ago), and it’s astonishing how well it works.

The amazing Goodson’s Oil Gallery Wax Stick.
The amazing Goodson’s Oil Gallery Wax Stick. Rob Siegel

Next week we’ll cover more techniques for stuckness for when the “aw, crap” moment has already happened.


Rob Siegel has been writing the column The Hack Mechanic™ for BMW CCA Roundel Magazine for 30 years. His new book, Ran When Parked: How I Road-Tripped a Decade-Dead BMW 2002tii a Thousand Miles Back Home, and How You Can, Too, is available here on Amazon. In addition, he is the author of Memoirs of a Hack Mechanic and The Hack MechanicGuide to European Automotive Electrical Systems. Both are available from Bentley Publishers and Amazon. Or you can order personally inscribed copies through Rob’s website:

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    Really helpful article. Just getting started in maintaining my vehicle; good to know in advance how to deal with the unexpected- thanks a bunch!

    Very helpful. The link came through the query, “Best gas for loosening stuck bolts” and here it is from the friendly folks of Hagerty!

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