How do I remove my muffler from the cat?

[burgermeister]

No remarks about "remove 3 bolts and muffler straps and it comes right off" please.

I was just about to take the OxyAcetylene torch to the evil automobile in retribution.

The muffler straps are off. I cannot separate the muffler from the cat. The 3 bolts would, even after a week of soaking with liquid wrench, only round off the inside of my sockets. So, I ground and torched the rounded heads off. Well, the remainder is still stuck, as good as welded. Tried pounding a chisel between the flanges. Made a big dent, but no more. Tried using a drift on the one bolt I have access to. Mushroomed over the steel drift. Tried heating the entire thing for a while. Rounded over drift some more. Tried drilling out the one bolt I can get a drill bit on. Rounded over tip of drill bit, no scratch on bolt leftovers. I'm all out of ideas. Even if I torch the muffler off and eat the $800, I'd have no idea how to get the cat flange off the remains.

All to fix a XX!@$#%& cam oil line that's hiding behind an AC compressor bracket that has 2 bolts hiding behind the muffler.

This may be auto mechanics 101, but I apparently need some more edumacation. Any ideas welcome!

[scottb]

Is it just the nuts that rounded off, or the bolt heads too? If the bolt heads are still OK, can you get a wrench on them? If so, have you tried putting them through several heat cycles (getting them cherry red) and then trying to bust them loose? Heat is your friend in this situation.

PB Blaster or Mouse Milk is the way to go for this stuff. I've found Liquid Wrench to be too mild. Others recommend Kroil.

Also, and with all due respect, if the bolts are rounding off the sockets, you may be using inferior sockets. Did you try some quality six-point sockets like Craftsman, Snap-on, etc.?

[Grady Clay]

Burgermeister,

“How do I remove my muffler from the cat?”
With difficulty.

Starting in’78 (actually some earlier), Porsche significantly improved the exhaust. Part of the down-side is that, here some 30-years later, many are still original.

My recommendation is you put up with all and any manner of difficulties and install new hardware, gaskets, clamps and other to bring the entire exhaust system back to close new serviceability. The main components can function for a very long time.

Exhaust components need to be easily removable to service lots of other parts. If left un-serviced for three decades, other jobs become very difficult.

Yes, the “blue wrench” (an Oxy-acetylene torch) is one useful tool. Another is a “death wheel” (a high speed cut-off wheel). Even Dermal works well in some situations. Safety is important here. The key is to destroy the old hardware and not damage the expensive components. Yes, I have saved original exhaust hardware from the '50s-'80s for reference but installed new current parts every time.

In my opinion, every few years (not three decades) all the exhaust hardware and gaskets should be replaced with new. Some cleaning and Hi-Temp paint is a good idea. At every engine repair, the exhaust studs in the heads should be replaced if not perfect.

Who ever heard of an ’88 Toyota or (heaven forbid) ’88 Chevrolet with original exhaust? Much less preserving it for another 30 years.

Best,
Grady

[burgermeister]

Like I said - the bolt heads are no longer there. I didn't really round off my craftsman 6-point wrench (no room for sockets) - just started slipping. After blue wrench + O2, now there's just the bolt shanks, which I figured I could pound out. And they're not budging. I agree with Grady - the exhaust needs to be serviceable. I just don't know how to remove something that can't be drilled or pounded out.

Just how hard can I pound on the cat/muffler joint before the cat's guts (no pun intended) disintegrate? I imagine not very - I probably already wrecked it, now that I think of it. Crap.

[Zef]

High speed grinder and a cutting disk will do the job...

[Porsche_monkey]

Mini-zip cut. replace with 5/16 stainless hardware and anti-seize compound of your choice.

If you have a lot of spare time do a search on muffler bolts and anti-seize compound.

[burgermeister]

I suppose I should have been more specific...

I would like to keep the original muffler intact. So there is no room for a cutting disc or roto-zip type tool that would get the bolts... the exhaust pipe is in the way.

Good thought starter on the carbide roto zip bits though - I'll see if the hardware store carries any - I could always chuck them in my drill...can't make it any worse. Or maybe they have some diamond tipped grinding point for a dremel??

I am also considering bolting everything back together and driving it till I get an exhaust leak, and then trying to pound some more on the bolt shanks....

[Porsche_monkey]

By mini-zip I meant a Dremel tool. It takes 3-4 small cut-off blades, they fit, you won't wreck anything. I did it.

[burgermeister]

PBH - do you mean cut inbetween the flanges where the gasket would go, and cut all the way around?

[boyt911sc]

Originally Posted by Zef

High speed grinder and a cutting disk will do the job...

You need to grind off the bolts heads or nuts flush to the flange surface. Then separate the flanges using a strong thin chisel. That will do the job but will need perseverance to succeed. Initially, it would feel like they are welded together. Actually, the heavy corrosion and heat has fused the metal surfaces together to form heavy adhesion metal to metal.

The heavy bonding is caused by the corroded 3 bolts and not by the flanges surfaces. An early sign of success is when you see a hairline gap between the gasket and the exhaust flanges.

Tony

[burgermeister]

The pounding won't wreck the converter internals?

I've got the bolt heads ground off (the top one is burned off, but gone just the same). I'll give the chisel-between-the-flanges one more shot tomorrow - kids are asleep, and me pounding in the garage below would cause oh-so-much trouble! I might torch off the nuts on the backside too, just for good measure - fun to see the sparks fly. Haven't had the torch out in almost a decade - I almost forgot how to set up the cutting tip...

Thanks for all the suggestion so far! Going to bed now.. will post results after my daughter's b-day party tomorrow, assuming I can get a few hours. She's bummed that she won't get a ride in her favorite car...

[masraum]

Very odd, My exhaust was original and VERY rusty. I had to cut all 3 bolt heads off with a dremel and then punch them out with a punch/drift/whatever and a big hammer, but that's all it took.

[MAS956]

I'd say you need to soak the joint between the muffler and the cat overnight with PB Blaster and use Steve's approach the next day. That'll git 'er done.

[jester911]

Dremel off both ends of the bolts and take a round punch to it. Not a big deal.
When you put it back together use SS bolts and silicon bronze nuts to keep it from rusting back.

[Doug Steinel]

How about removing the bolts that fasten the cat to the heat xchangers and then removing the cat and muffler as one piece. Then you can whale away at it on your bench which gives you many more options than when you are lying on your back under the car.

[Mo_Gearhead]

Hummm..... it sounds like you have a oxy/acet. unit? Carefully blow the middle of the bolts out with that. With them then 'hollow', you can drill out the remainder, or drive a chisel in between the flanges as you work.

Just use small cutting flame to keep flanges intact.

[mthomas58]

Originally Posted by burgermeister

All to fix a XX!@$#%& cam oil line that's hiding behind an AC compressor bracket that has 2 bolts hiding behind the muffler.

The horror! Watching with interest as I've got this same dreaded project in my future to replace a leaking oil tensioner line on the left side. I haven't even been able to get the muffler strap bolts to budge!

[Tim Hancock]

Heat whats left of the bolt shaft in the flange hole then pry with a pry bar between the flanges near that red hot/melting bolt. Once you get it started moving, the other bolts will start giving up their crusty hold. If you slightly mar/burn the muffler flange near the holes, who cares? An experienced torch driver from a junk yard could easily torch the centers out of those bolts lickety split, but I will admit that takes a bit of experience to do it cleanly. The flanges of both the muffler and cat are pretty beefy, so once you get a pry bar between them, you can really lean on the pry bar. Don't give up, you will get it!

[burgermeister]

Got it!

Using a punch on the bolts didn't budge anything. I am suspecting the fasteners were not SS, btw...

Soaking the whole mess with lots of Liquid Wrench overnight, and then taking a thin chisel to the parting line between the flanges, after taking a torch to the whole thing for 5 minutes to get it good & hot, did the trick. Oddly enough, I ended up having better luck with the 12 Oz hammer as opposed to the 20 Oz hammer.

Converter guts are now visible, and look undamaged - guess it can take a pounding, because I whaled on it for at least 20 minutes in total....

Also helpful for removing muffler strap bolts (mine were twisting the muffler straps due to heavy corrosion on the exposed threads, and I didn't want to buy new muffler straps) was a cheap chinese 5/8" wrench with the open end cut off and re-welded so the open end is at 85 degrees to the handle (as opposed to 15 degrees originally). Allowed me to hold the square weld nut on the strap with the wrench and save my muffler straps. They probably sell such wrenches, but I don't own any and Sears is 45 minutes away...

Thanks for all the suggestions & help!

[PeterCarrera84]

I had similar situation when instaling a by pass, used a Dremel, and I was just taking the cat out,. good luck !!! its a pain, and I was lucky , I had help.