How to remove a rusted bolt?

There are several ways to remove a rusted bolt. In this answer I am assuming that the person posting the question is properly differentiating between a nut and a bolt.

If the rusted bolt is embedded in, say, an engine block, one can sometimes dislodge it with penetrating oil like Liquid Wrench, although there are amny brans that do a similar job.

If that doesn't work, setting up a vibration by hitting the bolt head with a ball peen hammer might help break the rust bonds. Another method is to heat the block and the bolt with a propane or mapgas torch, the idea being that the differential in the heating and cooling rates of the two metals will cause the bonds to break.

During all of this, it is important to use a good quality wrench or socket set on the bolt head, If you strip or deform the head of the bolt, you will need to use what is commonly referred to as an easy out, a small tool which is cast sort of like a screw but wound counter clockwise instead. This is inserted in a hole which must be drilled down the center of the difficult bolt, and then the bit, inserted in a tap handle, is used to back the bolt out.

One last bit, if all else fails, sometimes you can drill the entire bolt out and then re-tap it with the next diameter bolt, or drill it oversize and use a Helicoil to re-line the bolt hole.

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Comments 5 comments

intouchwebpro 8 years ago

Another way is to build a dam with putty around the bolt (if possible) to hold about a quarter inch of liquid. Fill the dam with Coke, Kerosene, WD40, or Liquid Wrench, give the bolt a sharp tap with a hammer and walk away and let it set for a few hours. This way no undue stress is exerted on the metals and should release it's bond. What are you trying to get a rusted bolt out of? Dry ice has also been used in some cases but you really have to be careful with it.

Ernie profile image

Ernie 8 years ago

Thanks, great information!

Dan 7 years ago

heat the block and get a can of air turn it upside down and spray the bolt with the myst. Get the best of both worlds the heat on the block and the cold bolt.

Pronco 6 years ago

I knew my old propane tank and blowtorch nozzle would come in useful one day. Turns out they're indispensable for removing stuck screws and bolts after the strongest penetrants fail. Both my license plate screws on my trunk were rusted solid to the frame. Repeated applications of first WD-40 and then PB catalyst and banging with a hammer did nothing. I finally applied liberal PB catalyst and opened the trunk hood so the license plate was horizontal to the ground to assist the penetrant via gravity and let stand overnight. Next morning I tried to remove the screws and they still wouldn't budge. Plan B was to take a cheap blowtorch to them for about twenty seconds each. After briefly

applying a blue flame they unscrewed easily. So my solution would be to allow penetrant to stand overnight, then if it still doesn't work apply a blowtorch and see if that does the trick.

Steel Engineer profile image

Steel Engineer 3 years ago from Kiev, Ukraine

Good notes in the article and in the comment. Voted up!

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