How does one unclog catalytic converters most easily?
 

I just took off my airpump and sealed the tube. I did this not really for performance or aesthetics, but more because of the noise of exhaust coming up through the airtube making a loud put put sound that can be heard in the cabin with the soundproofing now removed.

I have a pair of aftermarket cats on a crappy summit h-pipe welded down right before the crossover tube, So I could technically get at the back of the cats if necessary. Could I run water through them? They're not clogged (yet), but I suppose they will be shortly.

What exactly is in a catalyst anyway and what would damage them?

They can't be repaired. Once they clog, they are junk.

What they said. And clogging will be a MAJOR hinderance to power. Hell, with what you said, it already IS a major hinderance to power. Replace them with high flows. If you don't want to spend that much money, get them off of there and run a pipe of the same diameter as the in and out of the cat through the center of it so it'll be like straightpipes...but that's if you don't have to worry about emissions. Note..it'll be much louder and stinkier with this..but if you're like me..that's a good thing!

Re: How does one unclog catalytic converters most easily?
 

Yeah, buy new ones. Their toast!

This explains why I'm always seeing uneven readings on my O2 sensors. The airtube only fed the passenger side cat by bad design. The drivers side sensor seems dead half the time. Probably extra back pressure there.

Will running it lean(ish) keep the cats from getting clogged up? I dont race much in the winter anyway

With converters, running excessively lean will cause the catalyst to become brittle from the heat, breaking up and traveling downstream with pieces either turning sideways in the pipes and clogging your system, or if you have a chambered type muffler a broken-up piece can get trapped inside, rattling around and hindering exhaust flow.... running excessively rich will cause the catalyst to melt from contact with unburned fuel, closing the very small passages that the exhaust has to travel through, also rendereing your system ineffective...

Running water through them isn't going to accomplish anything. It would be hard for me to determine whether they are still good or not without actually seeing them, but you need to get the car properly tuned or remove the converters all together (gut them or find someone with a welder that can weld a couple pieces of tubing in where the cats were... you could also 'gut' them, but the sound of a hollow converter is a strange one.

How does one unclog catalytic converters most easily? By unbolting the rear flanges of the h-pipe, getting a long metal prybar, punch, etc. and using a hammer to beat the living hell out of the catalyst (starting the car up every few moments, reving past 3-4k rpm to clear out what has been broken up) until nothing remains inside the converter shell. I can't describe the sound of a hollow converter, but if you can accomplish the above task, you'll know what I'm talking about. ...hope this helps some :)

i have done the above before..it sucks...its a pain...whats inside? its like a honey comb inside....there is also screens inside you have to rip out....i personally dont think its worth the time or effort

If at all possible, run a pipe through instead of gutting the cats. With them hollowed out, the air expands in the empty 'chamber' and when it's forced to squeeze back down into the exit piping, it creates a hell of a lot of turbulence and backpressure.

Well, I actually need the cats there because I need to get a sticker at some point. I'm counting on the fact that no one ever opens the hood during inspection. I'm planning on reconnecting the cross over behind the heads, cutting off the valve on the end and diverting some exhaust gas into the fender. I'm probably going to have to put the airpump back then

I dont know.... what kind of chance do I have with no emissions controls except a pair of cats and running a carb? Absolutely none, right?

Probably none. ;) Emissions checks are so picky...I know v6's that were EFI, had a cat on them, but were out of tune so they failed emissions.

I'm not familiar with the laws in Mass., but you wouldn't get in the door out here. Believe it or not, you can get away with a lot here, too, but you can't put a carb on a vehicle for which that wasn't a factory option.

Either way, replace your cats. Don't screw with them.

Take care,
~Chris

Hey Chris, Where do you get your smilies from?
Caymon

Hey man, Im in newton now and the best route, is to just get an OFF ROAD H pipe... and keep the CATTED stock pipe and switch them when it comes to sticker time... its ONCe a year... so you can afford to spend a day crawling under there and switching them... cause technicaly it's just 8 bolts.. they might be a bit rusted on.. but it can be done... it depends on where you go for the inspection... but all places put you on the DYNO... so you cant avoid emissions.... though i used to go to a dude in waltham, some russian guy, he wouldnt even look at the car, he put it on the machine and it was good to go... though he closed down (I wonder why) so I have to find another guy who's not so scrutinizing... but like I said, you cant fool the machine.. unless you have a real good relationship with your mechanic.. in wich case.. they have ways of MAKING it pass... :)
-as

I have a perfectly good factory h-pipe sitting in my attic and have absolutely no use for it whatsoever...hmmm...to bad your so far away...

I wonder how much exhaust gas I will have to divert to get my car to seem clean. I was thinking of getting clever and

A. Reattaching the cross over pipe behind the heads (cutting off the one way valve) and diverting the gas somewhere (fender?)

B. Clamping a hose onto the exhaust pipe airtube (now under positive pressure) and likewise diverting some more exhaust elsewhere.

Do I need the airpump or will these tricks be enough, ya all think?

I know an open minded mechanic, but it seems that in these dark days, even the open minded mechanics are starting to get cautious

without an airpump, how are you using the tubing that goes to the heads and the h-pipe? Your supposed to be pumping clean air into these ports, not taking exhaust out of them...

sounds like you are going to create exhaust leaks and think this will help you pass emissions?

the problem with "THE MACHINE" is.. it's expecting certain readings... and if they are off you fail... simple as that... generaly the machine can tell if theres a leak... not like it looks to see.. but I guess if the mix is OFF somehow... it's tough..since we're forced to deal with the MACHINE, you might as well put the air pump back on, it's not robbing you of any noticable power and do a pipe switch once a year, if you want, I'll come help ya some day
-as

Ok, here is the other idea I had...

I've got the airpump and I've got the tiny stock alternator pulley left over from my underdrive pulley install. I've pretty much got the pulley drilled to fit the airpump, so the airpump spins like there's no tommorrow. Will blasting incredible amounts of air solve the problem?

Should I blast the cats or the heads if given the choice or should I blast them both with air.

Why not just build a bridge out of matchsticks and drive to England?

Dude, you're making this so much harder than it needs to be. Stop tweaking on your car and do it right. It will save you time, money, and headaches, and won't cost you horsepower.

:)

Take care,
~Chris

P.S. Don't do the bridge thing either. Probably wouldn't work. ;)