weLL, any tips on this besides WD-40? I’m trying to get my catylytic converter off… but the bolts look like they’re starting to strip… don’t wanna be stuck with this thing forever… it’s those three bolts attached to the cat-back piping…
I’ve got new bolts, so will it be ok to just saw off the DAM THING??
air compressed tools will work… so will sawing it off…
i think
Plazz em off (you know, with a plazma cutter). Thats what I did and just replaced the old bolts with Stainless ones.
Ben
coca-cola man
i got my cat-back exhuast prof installed because i did not deal with the same issues you are having right now. I’ve done it once and it took the whole day and i don’t think its’ worth it. even the compressor did’nt help.
yea, dam impact wrench didn’t do squat!!! 200 lb-ft was good for nothing except stripping one of my bolts.!! :sick: Guess it’s time to pull out that saw…
Heat them up with a blow torch then give it a try. Always works for me.
I bought a dremel tool from wal mart and a extra set of cut wheels for the job of installing my cat-back.
Best thing about it is that you can return the dremel and get your money back… it is wal mart!!
Dremels are weak-ass. You need to get your hands on a 4" angle grinder. Beautiful tool, ranks up there with the sawzall I tell ya. It will eat thru those bolts like butter. Run to the shop and get some nice stainless ones and youre in business for years to come.
Jim
Heat them up with a blow torch then give it a try. Always works for me.
What’s that supposed to do? Won’t that make the metals expand?? making it harder to unscrew the bolt? Or does the intense heat make all the rust brittle? 
Heat up the nut, not the bolt, it expands and loosens. Use MAPP gas if possible, it heats up much quicker. Propane works too. I used map gas to heat up my cat bolts (never been off before) and I was able to break it free with just a 3/8" ratchet. A propane torch sells for around $10, Mapp is about twice that, but With propane you have to leave it on for a couple minutes.
Thanks, I’ll try that… sounds much better than sawing away those flanges and bolts…
I had to use a grinder to get my cat off. took only a few minutes to do. you’re gonna have to replace the nuts and bolts anyway so might as well cut/grind/saw the bolts off.
hacksaw
i took everything off from header back and then put my cat in a vise and used a hacksaw.
Those bolts are part of the cat. I don’t think you want to mess up the threads on those. Unless you plan to drill out the remaining pieces and thread a new bolt through? Anyway, on my first exhaust I used a torch to heat up the nuts. On my sister’s & g/f’s I tried my impact but rounded the corners of the nuts and had to use an air chizel - which is a very handy tool!
Originally posted by TIroneous
coca-cola man
Preach it brotha! 
lol
Hey man I would be real careful with the torch…too hot and you could snap the head off of the bolt.The best method that I have seen is to get a spray bottle fill it with water(the colder the better)heat up the bolt and then spray it with the water right away.The heating and quick cooling will help break the seized bound on the threads.If this doesn’t work you will probably have to torch them off the car.
hmmm, when I put my cat-back on, my neighbor had one of those air guns, like what they use at automotive shops. Used some WD-40, let it sit for a bit, then used the air gun and the nuts came off, but needed lots of pressure, like about 100-150lbs.
And this coca-cola thing, I have read that it works, it’s ph is something like 2.3 or something, you can use it get grease off your driveway hehe. So you can open a can of coke and sip some then pour it on the nuts and bolts. Hey why not, try it, may work better than WD-40.
These are some really good ideas…
But good grief!! It’s hopeless so far… the dam nut/bolt is practically WELDED onto the flanges by the rust… and probably welded to the threads w/ rust too!! I can’t even see the line where the nut meets up against the flanges!! It’s like the nut/bolt/flanges have merged to becom ONE friggin’ piece!!!
I’ll have to wait until I get a torch before I can try heating it up…
I don’t want to saw it off… I’m afraid the bolts will still be stuck inside the threads of the flanges after I saw it off the cat… and then there’ll be NO way to get the dam things out… which means i won’t be able to attach ANY new cat or test pipe to the cat-back piping…
so now i’ll have to try and wait to see if i can get a whole new cat-bat system first before i can even think about getting the dam cat off!!
THIS REALLY SUCKS!!!
When you go to reinstall your cat or (test pipe;)) make sure you use some anti-seize compound on the new hardware. Next time you need to take it apart it won’t even be an issue. I know this does not help with getting out the bolts. I would grind them off carefully, and then use screw extractor to get them out or drill out what remains and tap new threads. As someone else suggested using ss bolts is also a good idea. Hope this helps some. P.S. I have to remove broken/frozen bolts frequently and these are the methods I have found to work for me.