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Unread 09-12-2009, 10:03 PM   #1
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Default How To: Remove Rusted/Seized bolts.

We've all run into it. That one bolt that you need to get off to replace something, and you just can't do it. You blame yourself for being weak, throw your tools all over the garage, and give up. Well no more of that! Here are a few tips on how to remove severely seized bolts.

Rule 1: Never crank on a rusted bolt too hard. If it won't go, stop trying. Old rusted bolts have a tendency to just crack, and if you crack the head off a large bolt, you've got other things to worry about.

Tip 1: WD40 is useless. WD40 is a lubricating oil. It is great for light rust, along with it's other uses, but it does nothing in terms of seized bolts.

Tip 2: The best thing you can buy for a seized bolt is penetrating oil. The most common product is a spray called "PB Blaster". There are generics out there, and I have used those without a problem. Penetrating oil usually comes pretty cheap and a bottle lasts for a long time, so it's definitely a good investment. If you have a severely seized bolt, spray penetrating oil onto it so that it may drip down into the part where the nut is covering the tread. Sometimes just doing it once won't work. I recently worked on my front pipe exhaust and I sprayed PB Blaster on it for 1 week straight, daily. It still didn't let go after that and I had to use a different method.

PB Blaster visual:


PB Blaster can be bought for about 5 dollars at any automotive store.

Tip 3: Freezing products. The ideology behind this is that it causes the metal to contract, thus breaking the bonds of the rust. I haven't personally used any of these products but I have heard good things. These are more expensive than the PB Blaster, therefore I recommend trying that first.

Tip 4: Only do this if you have tried the other options above. If your bolt is so old and rusted that the other options didn't work, torch it. Yes, torch it. Like with a Propane torcher. I recently did this with my exhaust pipe and it came off with ease. When metal get's hot it expands and breaks the bonds on the rust. The downside of this is that if you torch it too hot, it is easy to crack the head of the bolt off. That would be bad.

When you torch the bolt, you should only torch it long enough for the bolt head to start glowing red. As Mr. Car Guy suggested, you can try heating it then cooling it with cold water, than using penetrating oil.

That's it for now. If those options don't work for you, then a pneumatic wrench is about the only thing left. You do run a high risk of cracking the bolt head that way though.

Last edited by Retrospekt; 09-12-2009 at 11:54 PM.

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Unread 09-12-2009, 10:27 PM   #2
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Had this problem when i swapped my tranny. There was an exhaust crossmember that bolts in two places onto the manifold, comes down, becomes one, and bolts up to the cat. Freaking things wouldn't come off. We ended up using a friend's torch (not a map gas, it was like uber high temp) and STILL broke two off.

That's what happens to exhaust bolts after ~190,000 miles
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Unread 09-12-2009, 10:31 PM   #3
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Originally Posted by wierdo124 View Post
Had this problem when i swapped my tranny. There was an exhaust crossmember that bolts in two places onto the manifold, comes down, becomes one, and bolts up to the cat. Freaking things wouldn't come off. We ended up using a friend's torch (not a map gas, it was like uber high temp) and STILL broke two off.

That's what happens to exhaust bolts after ~190,000 miles
Bolded part is your problem. It can't be too hot or you will weaken the metal so much that it will snap like butter. A regular weak propane torch is perfect. Hold it long enough just so that the head of the bolt turns red, then try turning. Heating too much is detrimental.

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Unread 09-12-2009, 11:37 PM   #4
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I have had to deal with seized fasteners for over 35 years in my profession.

When using heat to remove a rusted or seized fastener you need to heat the NUT, NOT the bolt. The heat is used to break up the rust, and most importantly expand the nut to release it from the stud or bolt.

Heating the bolt or stud weakens the metal and it can break before it comes lose. You also need enough heat fast enough to heat the nut to dull orange while keeping the stud/bolt as cool as possible to avoid expanding it and also weakening it.. You heat quickly and get the wrench on it as soon as the nut is hot. Too much heat and the stud/bolt gets too hot (weak). Your first attempt is your best chance at getting it loose. Every repeated attempt will overheat the stud/bolt. I use an oxy/acetylene torch but realize that this is not available to most people working on their cars. Propane will loosen a fastener that is not too seized but will do little on a real tight one. The best thing you can do with a torch that can't get the nut hot and douse the nut & stud with penetrating oil while hot and letting it cool a few minutes and repeat. Doing this a few times will expand the nut and shooting it with penetrating oil will cool the nut resulting in some of the penetrating oil being drawn into the threads.

In the case of some alloy studs & nuts, like on exhaust manifolds, the threads can seize and their is no way that you get it apart without damage. Either the threads strip or the stud/bolt breaks.
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Unread 09-12-2009, 11:39 PM   #5
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Quote:
Originally Posted by Retrospekt View Post
Tip 3: Freezing products. The ideology behind this is that it freezes the surrounding areas of the bolt and cracks the rust attached to it. I haven't personally used any of these products but I have heard good things. These are more expensive than the PB Blaster, therefore I recommend trying that first.

When metal get's hot it contrasts and loosens tension against it's surrounding. The downside of this is that if you torch it too hot, it is easy to crack the head of the bolt off. That would be bad.
Good write up except those two parts. Freezing causes the metal to contract essentially breaking the bond(correct thinking, wrong execution) of the rust. Where as heating the bolt causes the metal to expand in the hole thus crushing the rust and, again, breaking its bond.

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Unread 09-12-2009, 11:46 PM   #6
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Ah yes, over looked dealing with a bolt in a casting, the most trying situation. Even pros HATE this one.

Heating the bolt in this case is NOT the best. At least heating it very hot. You can heat gently and douse with penetrating oil and repeat, but you don't want that bolt to get too hot.

The best deal is to heat the casting if possible. An exhaust manifold for example can take the heat if you careful. If the area is near the cylinder head, the head will take the heat and not do much to loosen the casting around the bolt. If you can't getthe casting too hot, you can actually spray cold water on the hot bolt to shrink it to break the rust loose. After a few times use penetrating oil to cool it.

This definitely is an art.
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Unread 09-12-2009, 11:48 PM   #7
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Originally Posted by Mr Car Guy View Post
Ah yes, over looked dealing with a bolt in a casting, the most trying situation. Even pros HATE this one.

Heating the bolt in this case is NOT the best. At least heating it very hot. You can heat gently and douse with penetrating oil and repeat, but you don't want that bolt to get too hot.

The best deal is to heat the casting if possible. An exhaust manifold for example can take the heat if you careful. If the area is near the cylinder head, the head will take the heat and not do much to loosen the casting around the bolt. If you can't getthe casting too hot, you can actually spray cold water on the hot bolt to shrink it to break the rust loose. After a few times use penetrating oil to cool it.

This definitely is an art.
I responded to Weirdo and advised not to heat the bolt too much. I guess I should add that to the main post, huh?

Anyway, the heating worked for me. Like I said, I did a week of penetrating oil, nothing made it budge. I heated for 30 seconds and it popped right off. You do have to be VERY careful though.

Quote:
Originally Posted by TwIsTeDbOi View Post
Good write up except those two parts. Freezing causes the metal to contract essentially breaking the bond(correct thinking, wrong execution) of the rust. Where as heating the bolt causes the metal to expand in the hole thus crushing the rust and, again, breaking its bond.

Seems like you are correct. Thank you, sir! I appreciate the comments.

Last edited by Retrospekt; 09-12-2009 at 11:52 PM.

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Unread 09-13-2009, 12:08 AM   #8
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Just wanted to clarify my last post specifically, and all my comments about this.

My last post;
It is desirable to heat the area AROUND the bolt, not directly on the bolt. Then you squirt water first, directly on the bolt. Then follow that up with penetrating oil.

The whole thing here is you want to EXPAND the area around the external threads. That means you always want to heat the nut or area around the stud or bolt. This releases the threads when the expansion happens.

Heating the general area or even directly on the bolt can work if done at much lower temps. Any heating and cooling can help to release the fastener.
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Unread 09-13-2009, 11:51 PM   #9
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Just found the forum...very interesting..WD-40 a lubricant??? After all these years....didn't know that. Tried it......Always used it as a tool and equipment cleaner....and taking lipstick off the collar.

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Unread 11-24-2009, 07:12 PM   #10
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Interesting point about WD-40. Perhaps it is why I am having such problems repairing my exhaust system. While replacing the gaskets between the flanges seperating the catalytic converter from the muffler and the exhaust pipe I broke 2 studs, striped 2 stud threads, and managed to get 2 off with great effort. Yes, I used WD-40. My question is how do I get those studs out of the flanges. They don't pound out! At least they aren't for me that is. I am assuming they are like lug nut studs since they have a round head and a threaded shaft. If it helps, it's off a 96 Blazer. I just spent the day fighting this beast and am thoroughly frustrated...and have the busted knuckles to prove it.

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