I'm putting a cat-back system on a friends 1995 325ci. Normally I hate exhaust work, and avoid it like the plague, but I wanted to help out a friend.

Is there something I can do to make the exhaust bolts more willing to be unscrewed...or is there a special technique? This favor could turn into a nightmare if I have to spend my day drilling stripped bolts.

WD-40 and elbow grease.

any kind of liquid wrench should do the job. wd-40, pb blaster, gunk has a version too.

Get PB Blaster or Liquid Wrench from any auto parts store. Try and soak em overnight for best results

torches work

Don't work for free.

The rules of my garage/driveway work for others is this: You buy me lunch and any specialty tools I'll need.

^the double cheeseburger is already in my belly!

I would try the WD-40 or PB Blaster options. Also, I don't know if it will matter or not but maybe it will be easier if the exhaust is hot. Obviously you'll need to be more careful not to burn yourself. When it's cold it's all contracted and tight so maybe when it's hot it's good and loose.

If the bolts really are stuck because they're rusted, I think expansion by heat won't make a difference. Although it's always worth a try, if you're reallye careful!

Any progress? I just read that some automatic transmission fluid might work on rusty bolts. You'll probably need some kind of applicator to get it on the threads. I've never tried it though so it may be a waste of time.

I was all set to do it yesterday, but BMW ordered the wrong gaskets...so were gonna try attempt #2 sometime this weekend.

Just the other day I removed a ball from a hitch. I found the piece outside (who knows how long it was outside) and I thought I was wasting my time by trying to remove it. I liberally applied Liquid Wrench to it, let it soak over a weekend, and used a rosebud tip on an oxy-acet torch till the nut was orange. It came off like a piece of cake.

If I were to try this on a small nut such as a exhaust piece I would use an air/acet of MAPP torch.

I work at a shop and I Always use heat if the bolts are rusty.

First, Clean the threads and bolts/nuts with a wire brush/wheel, find a 6 pt. socket that sits very snug (9/16") is your standard exhaust nut, but when rusty I would suggest a 13mm hammered on to "test fit" then remove the socket. Next, take the torches and heat the nut until it's glowing cherry red and hammer your socket back on and loosen.

If the are "press in" studs, hammer them out and use a "Nut/Bolt" combo with flat washers and a lock washer.

If the studs are threaded into the flange and don't unscrew when you try removing the nuts, heat the flange and use vice grips to unscrew.

Always replace rusted studs!

If you don't have access to a torch, I would suggest taking a peak to see what type of stud it is, if it's "press in" then it wouldn't be so bad if you broke the stud because you would be able to just hammer it out once the flange is removed.

Although, if you strip the nut then you will be forced to cut the nut off no matter what. (this is why I say find the tightest fitting socket before you try removing the nut, just remember to clean it as much as possible before doing this.)