Marc Shaw

Okay - I fought with rust-frozen nuts for 2 hours on Sunday to get the heat shields off my cat.

Then I spent another 2 hours tonight cutting off the ends of the bolts from the cat. to the heat exchanger as they were also frozen solid with rust. I also cut the bolt from the restraining strap holding the cat. to the primary muffler.

I still have not been able to remove the cat. so I'm considering dynamite or a blowtorch.

Having not used either before I am wondering about technique -- just heat up the flange of the cat. using the blowtorch to expand the metal around the bolts? Then what?

Thanks.

Marc
p.s. Bates - I might take you up on that plasma cutter after all!

Smokin

Marc... You can try heating it up and breaking it loose or just using a cutting torch to cut the bolt/nut/rusted thingy off. Using a cutting torch is easy... You just need to be very careful what you're next to and where the slag and sparks go.

chancecasey

I know this is probably a dumb question, but, did you try several "coats" of wd40 or some kind of rust buster? I've found that a quick blast, 2 or 3 times a day, for 2-3 days can make a huge difference.

N51

Marc,
A small propane torch(I'd use MAPP gas for it's efficiency) should do the work. Just heat the nuts to a nice cherry red, and they should twist off "like butta'". My Fabspeed cat bypass bolted up perfectly. Didn't have to use a torch, but it was a California car. No salt/rust.

Best,
Noah

Marc Shaw

Thanks all.

Chance - yes, Liquid Wrench daily for the last week before starting...

Rick/Noah - the problem is that the nuts are already off - I cut them off using the angle grinder. The bolts are still fused in place (nutless) and the flanges are "welded" together with rust.

Marc

springer3

Marc:

The cat has to be removed to adjust the valves. Who did that last, and when was it? Mine dropped with no drama at all.

For your situation, heat is good if you can avoid damage to neary by parts. Vibration is good - an air hammer will break up rust. A brass drift punch with a hammer might help loosen up the rust. Be sure to wear hearing protectors in either case. Noise is reflected off the car and off the ground, and your ears will ring if you don't protect them. Cutting torch? Probably will not be necessary.

Good luck.

dutchcrunch

once you get the cat off. turn it so that the bolts studs you are trying to remove are in the up and down position so you can make a pool of rust blaster around stud and let it sit. you then can go to the back side and twist out with vise grips. or drill and use bolt extractor. do your self a favor and apply high temp anti seize to all the new hardware, to make it easier in the future. if you ever remove your heat exchangers do the same as no car manufacture ever does this and once they set up over time and start to rust its a pain to remove. you are lucky that that its only your cat and nothing more serious

greenjt

Marc - Please let us know if you end up trying the dynamite approach. I am curious to know the outcome. ;-)

Bates

Marc:

From what I hear at from the heavy truck service centers, you just heat the bolt for a few seconds and then whack it with a hammer. You might want to mind where that cherry red bolt will land.

The offer on the $4000 hydraulic bolt cutter is still available...I'll even give you 30 day terms .

Arrivare

I would suggest that you drive a fox wedge into the gap between the cat and the exhaust and this should open up a gap either to get the Cat out or sufficient to insert a hacksaw to cut through the bolts.
Good Luck
Allen

Marc Shaw

Here's a thought....are the bolts threaded all the way through the flange??

I assumed (after looking at the PET diagram) that the flanges were not threaded and the bolts were only held in place by the lock nuts.......but are the flanges threaded too???

Allen - what is a fox wedge?

I was thinking of trying to drive the air hammer between the two but don't want to damage the heat exchanger (I'm not worried about the cat. - if it survives, it goes on eBay anyway).

I think I'll pick up a Propane/Oxygen Cutting Torch at Canadian Tire on the way home tonight as I did a Google search and it seems propane alone (like a plumber's torch) is not hot enough.

Bates - I'm confused - if I heat the bolt, won't that make it expand and be even more stuck? Shouldn't I heat the metal around the bolt?

Thanks...Marc
p.s. I'll post pictures if I resort to dynamite.

Dunasso

Should I even comment? Well.....OK.

If you have successfully removed the heat sheilding this could be an option for you, It worked for me.
I used a hack saw to cut through the gasket between the Cat and the manifold sawing the bolts as I went. After the Cat fell to the ground, I had plenty of roon to beat the remainder of the bolts out of the Cat and the manifold with a drift and ballpeen.

Duncan

PS, replace the bolts with SS and use steal or brass nuts (not SS nuts).

Red rooster

Marc,
The flanges are not rusted together .There is ( or should be !) a gasket between them . Sounds like a bit of heat and violence should do it !!
The trick is to get something moving .All the suggestions made are good. The flanges are tough so little danger of serious damage .
I would try a combination of driving an old screwdriver between the flanges and driving the most accessible bolt back through ,using a proper drift and a meaningful lump hammer ( 2 lb head ) .
I guess that in your work everything is approached with great care but this job needs brute force and ignorance !!

The very best of luck

Geoff

jimq

Use a SAWZALL the enforcer! It will cut them apart alot faster then a hacksaw

chancecasey

No the flanges aren't threaded. You should be able to punch them out with enough force if you have room for a heavy hammer - or maybe try a small gear puller for the initial push. My puller has a pointy center thingy that would probably get it the first 1/8" or so. Not sure if you could get enough torque on it or not but worth a try.

Please use video if you go the explosives route