Favorite exhaust rust busting technique?

[mmw]

I am trying to drop the exhaust on my 94 325is for a flex disk replacement, and while the nuts on one exhaust flange came off fairly easily (albeit with an impact wrench), the other flange nuts refuse to budge, no matter how long I have the impact wrench hammering away. Of course, this is the rear-most pipe, a bit harder to get at. Yes, I used some lube, it's soaking overnight for another try.

Does anyone have a good technique for getting things like this off without ruining the studs on the manifold? Thanks for any insights you may have.

[mullethunter3]

I've never encountered a bolt that wouldn't come off without a little WD-40 or Rusteater and some time.

[nick_318is]

I would say try some PB blaster on it and let it soak in, and maybe hit it a few times. Then get a big Breaker bar and go at it if the impact won't do it.

[HyeTide]

Try using heat from a torch to loosen rust, but have a fire extinguisher handy.

[nick_318is]

Also if worst comes to worst get a sawsall, i did when I changed my exhaust out last spring.

[mmw]

Thanks all, the heat did it.