Cat removal, after heat - what next?

[VFR750]

I am trying to remove the cat.

I have:
1) cut all the nuts and bolt heads off
2) soaked the flanges in liquid wrench for three days
3) tried to beat the remaining studs out of the flanges with a 5lb sledge hammer and drift - no movement at all
4) heated the flange for 45 minutes with a propane torch. Nothing happended
5) whacked the joint between the flanges with a sledge and a cold chisel.
6) used the muffler as leverage to pry the flange apart.
7) put a jack under the cat to try and lever it apart.

The only thing left to try is to drill out the bolt shanks (on the few I can actualy reach) and/or put rust dissolver on the joint.

What esle is there to do?

What am I doing wrong?

[dfink]

Stupid question but did you get all 6 bolts out. A couple of them are hard to see....

[jbrinkley]

Mapp gas will work better. The yellow bottle if you're using those.
much hotter
or rent a real toch

[Zef]

High speed air grinder with a cutting disk...15 minutes job.

[VFR750]

Not a stupid question, I got all 6 out. What a bear to get the two next to the shock. Plus cutting off all the heads to the heat shield, so I could get better access to the two lower bolts. Plus destroying one of my muffler straps, due to rust.

Funny how the car is rust free, but the exhaust is every bit 25 years old! :-(

I was using Propane. MAPP should get it hotter, but how hot am I looking for?? Cherry red?

I saw the post on using a carbide cutter (drill) for drilling out the bolts. That may be next.

[dbrisson]

I was lucky when I removed mine from an 82 sc to have air tools.

Once the nuts were cut off with a cutting wheel I used and air hammer with a punch to remove the studs.

I replaced them with new grade 8 bolts and all is complete.

[VFR750]

An air hammer? Wouldn't that just beat the heck out of the exhaust pipes?

Or am I being a little too cautious?

[dfink]

Wow those bolts must really be rusted. I had to cut off the bolts on mine but then it just fell part. Maybe try something thinner than the chisel like a metal shank putty knife. Something that could get into the crack. If you could get to a shop they could probably use a torch to blow the bolts out of the holes.

[VFR750]

After thinking about it all night, I've come to the conclusion the remaining portion of the bolts must come out. I guess the rust in the holes is acting as if the nut and the bolt head are still there.

So best way to get the bolts out: Drill, air hammer, torch???

Going to a shop is out of the question. My wndshield is out. The "other" project, aka replace the dash, is taking a back seat right now. The cat job is taking WAY to much time.

I know one thing for sure. SSI's will only happen when it is time to rebuild the engine. The head studs don;t look any better than the bolts on the cat.

[jbrinkley]

if you dont care about the cat I'd cut it off behind the flanges with a real torch, I think home depot has small cheap ones, harbour freight also. Then you'd have room to work the flanges. Mapp gas will get it red hot and then you culd take the garden hose to it and hope it gets loose. it's a time vs. money thing

[dfink]

Did you try the thin blade approach. Just to get something in between the two halves. The cutting torch take a little technique to not cut the flanges maybe not a good idea. I can't even imagine the time it would take to drill them.

[VFR750]

I'm trying to keep the cat. It works fine.

I thought about a hack saw blade, and cut down through the joint where the gasket is. But that is low on my list.

I'll try drilling fist and see how that goes.

[dbrisson]

If you drill make sure you use high strength or carbide bits or you will be there forever.

The air hammer I used was the punch attachment in an air chisel. Once the nuts were cut off there was a flat spot to put the punch piece. Pull the trigger and the remaining bolt portion backed right out. They were soaked with pb and one did require a bit of triggering. The flange was still straight after the ordeal and the cat is hanging up on the wall in case I ever need it for emissions.

After the bolts were cut I was able to pull on the cat and create a bit of wiggle. Once I did that I could wiggle it until 3 remaining studs were a problem. I took the cutting wheel and made those areas flat against the converter flange even taking a small bit of metal from the flange. Once they were totally flat the converter wiggled of the remaining studs with force and left 3 studs still in. Then back to the air hammer with punch bit and they drove right out.

Remember the air chisel is concentrated force on the small bit unlike pounding with a hammer and possibly missing the point you actually want to impact.

[JP911]

If the cat is 25 years old, then it may very well be toast. I would use a sawzall to cut away the cat at the flange, and then deal with the remainder of the cat with a drill and/or air hammer.

[Rowin]

I just did the same project today. The same 2 bolts where a pain. After every thing else failed I used an air hammer and it worked well. Now its time for me to get new bolts and put it back together.

[VFR750]

After all this time the CAT seems to be OK. I've passed emmisions with flying colors (altough many posts here comment on how easily they pass without a CAT) So until proven it is NG, I want to keep it in working order.

While I have an air compressor, I don't have an air chisel. With Christmas so close, I guess I'll put that on my list.

Concentrated force verses smashing fingers with a sledge? Where is the fun in that?!

In the mean time I'll try the drilling method. And let you know how it goes....

[VFR750]

OK. A small update.

I think I can drill most of these bolts out. After 45 minutes, I am ALMOST done with one. :-(

The bolt is completely rust welded into the hole. I've never seen anything like this. Even with a big hole in it, I still cant get it to budge. I think water must have gotten in, and as the rust expanded it has compressed in the hole and locked the threaded portion of the bolt into the hole. Like an expansion bolt used to anchor stuff in concrete.


So I am carving out the bolt with a carbide cutter from the inside out. And I am finding rust inside the middle of the hole.

This is officially NUTS!

I have all winter, it might take that long.....

[VFR750]

Another small update.

The first bolts is out!! And it was glued into the hole by rust.

I have now put rust desolver on the other bolts in an effort to break the bond. I have managed to wear out my steel drill bits, plus it appears I tackled the easiest one first. I need more cutting power.

I went to McMaster Carr and ordered a couple of 1/4 carbide burrs. Based on my Dremel tool with a 1/8 carbide cutter, this will work, but the small size is too slow. 1/4 should increase the cutting rate.

Plus I only need to go half way to get the joint apart. A humorous relevation, while underneath the car, in a very awkward position, trying to get the drill bit to dig in and cut. Half way! Why did I not think of that earlier! ;-)

My Christmas wish list now offically includes an air-powered right angle grinder. Hello Sears gift cards.....

And Merry Christmas to Wayne and Co. at Pelican for providing this forum. Thank you.

[VFR750]

I finally got the cat off this evening!!

Santa got me a 1/4" right angle grinder and a set of carbide burrs. How nice! Boy does this thing go through metal!! It's got the power and torque to drive the 1/4" diameter burr and not bog down when I really pressed on it.

After 1 1/2 hours of grinding away, I finally removed enough of the bolts to get the joints to seperate. The cat/muffler is off.

I still have to grind the remaining portions of the bolts out of the holes, but now, access is very good. BTW, I had to remove the shock to get more room to move.

Thanks for everyones help.