Tech Articles

How to Remove Rusted Bolts and Loosen Stuck, Seized or Frozen Nuts and Bolts

Corroded bolts like this are a common sight for gearheads. But trust science, not a lucky horseshoe, to get it un-stuck. (Image/Thester11, Creative Commons)

A rusted, seized bolt or nut can turn an easy project into a nightmare.

In fact, mechanics have been known to hold a lucky rabbit’s foot or refuse to work on Friday the 13th for that very reason.

But removing a stuck bolt doesn’t rely on luck—it relies on the proper preparation and tools.

Plan Ahead.

If you have the luxury of planning a bolt removal in advance, then take advantage of your head start by spraying the bolt with penetrating oil.

A quality penetrating oil does two things:

It will act as a mild solvent to eat away at rust, plus it will lubricate the threads, which will make for an easier extraction (and mitigate the risk of snapping a bolt due to corroded threads.)

Some folks will make their own blend of penetrants using common garage substances like automatic transmission fluid, acetone, and candle wax—but we’re inclined to trust the off-the-shelf stuff.

Start several days in advance, spraying the bolt or nut every day with a fresh blast of penetrant.

Don’t be stingy—really soak the nut or bolt down. Allow the penetrating oil a good chance to creep in to the bolt threads.

If the bolt or nut is located in a tight space, try to remove as many obstacles (brackets, panels, etc.) as you can to ensure your socket and wrench/breaker bar has enough room to seat and turn properly on the fastener’s head.

Use the Right Tools.

When it comes time to remove the bolt, take your 12-point socket and hide it in your sock drawer next to your four-leaf clover—you won’t need either one.

Use a 6-point socket for a traditional hex-head bolt. That will reduce the chance of accidentally rounding the head or nut.

If your bolt in question is an Allen or Torx, make absolutely-positively sure you’ve got the right-size bit. (AMC and Jeep folks know what we’re talking about.)

Take a wire brush and knock-off any corrosion on the bolt head. You want to ensure your socket is seated fully onto the fastener.

Don’t lead off with an impact wrench or breaker bar. Instead, try to see if you can break the bolt free with your trusty socket wrench. You don’t want to risk shearing the bolt head off with unnecessary force.

Greek History Time!

If, after all that, your bolt is stuck—call Archimedes.

Archimedes was an ancient Greek gearhead who was the first to mathematically explain the mechanical advantage of a long lever. In other words, he helped invent the breaker bar. Applying gentle force, use the bar’s leverage to apply more turning strength to the bolt head. Feel is important, and if you think you’re going to round or shear the bolt head, back off the fastener.

Using something like a breaker bar or wrench extender can give you a powerful mechanical advantage. (Image/Mueller Kueps)

If a breaker bar still won’t release the bolt, it’s time to contact Prometheus.

In Greek mythology, Prometheus stole fire from the gods and gave it to the mortals. Now, thanks to him, you can use that fire to un-stuck your bolt.

Using a torch, heat the bolt head or nut. Due to thermal dynamics, the bolt or nut will expand. The hope is that expansion and contraction process will also un-seize the bolt, breaking the corrosion that grips the threads.

Obviously, you’ll want to take great care to avoid any damage caused by the intense heat. Clear away any solvents, and make sure you’re not using your torch near a fuel line and oil-weeping gasket. Your torch will also quickly melt plastic and rubber, so be mindful of bushings, mounts, and boots. (Mini torches and induction tools are really handy for this sort of job.)

Keep the heat centered precisely on the bolt head or nut for about 20-30 seconds, and then let it cool.

Though opinions differ, we recommend waiting for the fastener to cool back down before you attempt to turn it. Again, the magic of this method occurs in the expansion action breaking loose the corrosion.

Heating a bolt is an effective way to get it un-stuck, but be careful! (Image/Summit Racing)

Impact Play.

An electric or air-powered impact wrench is the stuck bolt’s arch nemesis. If you’re lucky enough to have one, remember to try to loosen the bolt by hand first—too much torque too fast can spell disaster to a rusted fastener.

In addition to the rotation strength of the wrench, the impact action will help shock the bolt free, loosening corrosion that may be gripping the bolt.

Preventative Maintenance.

There are several things you can do to help prevent the bolt getting stuck in the first place.

  • Proper Torque. Avoid over-tightening bolts.
  • Thread Lubricant/Anti-Seize. Apply a quality thread lubricant to the bolt or stud to prevent seizing caused by galvanic corrosion.
  • Paint the Fastener Heads. A simple coat of spray paint will keep rust and corrosion off the fastener head, and prevent moisture from creeping into the threads.
  • Brush Up. Don’t be shy about occasionally using a wire brush on the fastener head. It will keep muck and moisture out of the threads.
  • Add a Coat of Grease or Oil. If you’re unable to paint the heads, then periodically spraying them down with a penetrating oil or applying a small dollop of grease will work just as well. It’s also smart to do the same thing to the bolt’s threads, if they’re exposed behind a bracket.

A Lucky Turn?

Hopefully, following these tips has been helpful, and your bolt or nut is lying harmlessly on the cement in front of you.

If it isn’t, and you’ve rounded your fastener head or sheared it off completely, don’t despair.

There are products out there to remedy a rounded nut and extract a broken stud—and none of them involve knocking on wood, wishing on rainbows, or crossing your fingers.

A broken bolt isn’t the end of the world. There are stud extractors and other specialized tools, like this one from OEM Tools, that can help. (Image/Summit Racing)

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  1. Good article. One thing that i would add is whats helped me many times. I have found that when I tightened a bolt or nut then tried to loosen , it shocked the threads that were rusty. As I loosen it , if it starts to get tight i tighten then loosen again. I use plenty of wd40 while going through the whole process. Saved me many times using the repeated back and forth motion. Also if you can get to the thread on the back side of the bolt whire wheel it or brush the rust off.

  2. Right. You can easily use a breaker bar or a box and ranch two quickly apply Force back and forth to loosen things up.

  3. Box end wrench … For chrissakes.

  4. Harley Morris says:

    You can use a hammer and hit the head of the bolt after it cools to free it from rust.

  5. Altho the article’s author says he trusts commercial products more than homemade concoctions,but doesn’t share his reasoning. There was an article in a machinist magazine that scientifically tested commercial products versus a 50/50 mix of acetone and ATF on rusted bolts and nuts and the upshot is that the acetone/ATF mixture beat all the commercial products, although some came close. My own experience is the same. If a penetrant will work, the homemade works rather quickly (10-15 minutes). I don’t buy commercial penetrants any more as the homemade works better.

    • OnAllCylinders Staff says:

      Hey John, sorry about the late reply. My logic in that statement is for simplicity’s sake. A lot of folks may not have surplus acetone or ATF on the shelf, whereas a can of the spray penetrant can be sourced at any hardware store for a few bucks. By all means, if you’re comfortable enough and have the raw materials to make a homebrew, then proceed.

  6. Daniel Wilson says:

    I’m not sure why older posts like this one just appear out of the blue and display on my eye phone. It might be a good omen about the usually simple task of changing the plugs on my GTP that I will be doing tonight.

    The article did have a few good methods of dealing with stubborn fasteners. The Greeks were historically the first to curse to their Gods in frustration about rusted and eventually stripped small block Chevy exhaust manifold threaded fasteners.

    I’ve tried calling Archimedes as suggested in this story, for help with my Roman Chariot restoration project. But his abacus pulsed cell phone is ancient at best and the micro internal sundlal speed fluctuations are incompatible with the afterlife internet.

    I’ll call on “The Golden Greek” next time. Chris is much more contemporary than Archie.

    And the beat goes on….

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  8. Wallace Gordon says:

    I’ve been using 50/50 mix acetone with atf fluid for over 25 years always with great results. Although the past ten years the mixture doesn’t mix well, eg it congeals, so I mix a small amount as and when needed. Doesn’t smell too good but it beats anything I’ve ever used even spanner in a can which is very expensive. I remove injectors from the infamous M9r engine and it works really well if left overnight after a drenching. The acetone is an excellent penetrating fluid by itself and mixed with a light oil atf it’s an excellent penetrating fluid all in. Keep your pleasant smelling penetrating fluids that don’t do swot I’ll stick to the smelly working stuff.

    • Thanks so much for the suggestion of 50/50 mix of acetone and ATF, worked like a charm when everything else I tried wouldn’t budge it!

  9. …And sometimes, nothing works. I have an ’08 F-350 that I’m currently deleting (July 2019). EGR cooler bolt (that’s right, just one) wouldn’t come out. Tried everything shown above many times over a couple weeks’ time–nothing. Took it to a mechanic who ended up using an acetylene torch to get it out. Cost me $350, and that’s all labor.

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  11. Jim Cannon says:

    Just wondering what is the smartest thing to do about rusted bolts nuts in my rack which I carry wood and kayaks all the time and need to desolove the rust on them I don’t want them to break I’d rather save them from snapping got a great idea please help??? Thank you very much!!!

    • Hey Jim, I’m not sure if you’re asking how to prevent it or how to remove ’em.

      If you’re removing bolts, have you tried any of the above techniques? You may just need to cut them off with a wheel and get new bolts. (Dunno what your strength requirements are, but you could go stainless, or step up to zinc-plated Grade 8 if need be.)

      What I can advise is, when you re-install your bolts, make sure to use a good anti-seize thread lube. Then, you can hit the tops (and backs if possible) with a shot of spray paint or WD-40 to shield against corrosion.

      ^^That’ll make them easier to remove in the future.

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