Best way to tackle removing stuck spring bolt?

[98Base4R]

The pic is very similar to what I am trying to do: remove stuck spring bolts. The spring bolt has a smooth shoulder and a short threaded section. The smooth shoulder is rusted to the exhaust flange. It is under the car, so it isn't easy to swing a hammer at it. And I don't want to bend the flange. Some things I have tried:

1) Sprayed with PBB
2) Hit it with a hammer
3) Rattled it with an air chisel
4) Tried to twist it with vice grips

Some other thoughts I haven't tried:

5) Heat up the flange while twisting the bolt with vice grips
6) Take the pipe off the exhaust manifold, to get it out from under the car (easier to work on)

This is the last piece of the puzzle before re-assembly. If this was your project, what would be your go-to solution for this?

Thanks in advance,
Richard

 

[ARC]

Edit*** Rereading I'm not sure what you are trying to do.

Heat is likely the only solution. Get it as hot as possible with a torch turn the nut as much as possible before it cools. Heat and repeat until you get it apart.

 

[MStudt]

I had the same thing happen on mine. I ground the bolt smooth to the flange. Use a center punch on the bolt, and then drill it out.

 

[98Base4R]

Both replies were on point. I bought a Bernzomatic BZ8250HTKC Map-Pro Hose Torch Kit which includes the Mapp gas bottle, a hose and torch. The torch ignites with a push button.

After heating up the bolt to red hot it was free and would turn. It stayed free after it cooled down. Unfortunately, the bolt had mushroomed until it was larger than its hole. So I borrowed a Milwaukee cordless angle grinder with a cut off from work and cut it off even with the flange. A quick pop with a punch and both bolts popped right out.

Re-assembly of the exhaust took a fraction of the time that getting all the bolts out did. I understand why exhaust shops replace so many parts when the work on a car. It takes a ton of time to get things apart without cutting.

Thanks for the help.

 

[SilverRidgeRunner1]

Similar idea but heat the bolt to red on temp spray with lube ... The lube cools the metal down at the same time soaking into the metal and around the threads. I've had a lot of success with this method. But cutting and drilling would be just as easy.

 

[Toyotadude88]

I Agree. Get the manifold around the bolt cherry red hot and it should then release the bolt.