What causes Cats to fail?

[Straight6Jeff]

Hey everyone,



I know this is a gasser question, but what causes cat converters to fail? I had to gut my 3rd set today, and I only have 24k on the clock. The first and second set were replace under warranty at 3k and 13k respectively. I don't tow very often. When I gutted the cats today, both converters rattled like a morracca. I know on the v-10 boards this is a common problem, but is it just poor quality, or is their an underlying issue? I intend to put a set of high-flow converters on in a few weeks.





Oh yeah, the exhaust note is not that much louder with them gutted, but it sounds very wierd. The Spin-Tech muffler make it sound like a cross between a turbo and a choking gorilla. The engine feels like it rev's quicker, however, the butt-dyno has been know to be wrong.....

 

[C Schomer]

My Ruger Ranch Rifle will cause a cat to fail! Sorry, couldn't resist! Mine plugged up with soot. Some plug from 'poisoning'. I've cut a few of them apart but haven't seen one of the cores fall apart. Sounds like a mfgr problem! Craig

 

[Chad Sheets]

Cats take in all the nasty stuff from your exhaust. They should last a while, unless you are burning crappy fuel or fuel that contains high percentages of things that plug them up. No reason why yours should not last a while.

 

[Bad340fish]

Those things are wierd. My had has an 89 Shelby Daytona that has been through more o2 sensors than should be allowed by law. When the o2 sensor goes out on those it goes full rich all the time. The thing black smokes like a Hot PE lol. It now has almost 200K on the clock and with everything from Antifreeze to way to much fuel going through that Cat it still is good... . I have no idea how. You might scan the codes and see how the o2 reads possibly. I know its a V10 and the mileage sucks anyways but has it gotten anyworse lately??



Don't waste your money on the high flow converters. Hot Rod Mag did a test a while back and found the converters off of like a 98 GM truck outflowed even the best aftermarket ones. Can one say Salvage yard I would think(its dangerous I know) that all 96 and up Gm trucks with the Vortech 8s would have the good converters on them. Good Luck

Clark

 

[HDH]

What cause's a Cat to fail?

In a Gasser running beyond stoichiometric (SP?) (More than 14:1 air fuel ratio on the rich side) will cause the cat to overheat and burn out. Thus causing a higher than allowed amount of Hydrocarbons into the Atomsphere. Check your O2 sensor. Or could it be that the Cat was too small to begin with? They do have a flow rating.

In Caifornia,The law here says that every Cat must have a 50k mile warranty on them,so if everything up stream is within spec's,Then the replacement Cat is free. .



I Hope this helps.

Doug.

 

['956Wheel]

cat "gutters" beware

That stuff in the catylytic converters is cadmium, one of those heavy metals that is a known carcinogen (cancer causing) be real careful if you gut it rather than stick it in the basement.



Mike

 

[Straight6Jeff]

Thanks for the reply everyone.

I realize that the cats (two of em) would be replaced under warranty, but I'm thinkin that the next set will do the same thing. My gas mileage has been around 7 in the city, 11 highway. It really hasn't changed much since new. That doesn't mean it didn't have a problem since new.



Headers are going on it in a few weeks, so I'm gonna throw a new set of O2 sensors in.



I'm kind of leaning towards the notion that they are undersized. Even though there are two of them.



I kind of like the sound without... ... .

 

[RustyJC]

Jeff,



Strange... we towed 5th wheels up to 36' & 13,500 lbs GVWR with our 1996 V-10 3500. We sold it in September with 45,000 miles on it and had never had to replace an O2 sensor or a catalytic converter. Wonder what's different between your V-10 and ours?



Rusty