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A pic of my clogged Catalytic Converter...

Some of you followed my thread about my nightmare attempting to smog my Porsche. Well, it finally passed when we pulled the OEM catalytic converter off and replaced it with a new one. While my old CAT was out, we gutted it (for science)... and I was shocked to see how melted the guts were! It was seriously choking the car.

It goes without saying, the Porsche runs much better these days - and about 10 full degrees cooler across the board (I never thought that would happen).

Here are a few pics of my clogged CAT for the archives. This thing must have gotten very, very, hot...

Side view (it is normally a full circle - this is just a broken portion):



This is a view straight through the CAT element:



And a view from the back (this is what the element is supposed to look like):

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Last edited by Emission; 02-11-2005 at 10:37 AM..
Old 02-11-2005, 07:26 AM
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Wow, I guess this is what I've avoided all these years when I took the Cat off of mine upon it's entry into the USA.

What is that white stuff clogging it? It looks cellular, closed cells and all.
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Old 02-11-2005, 07:32 AM
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Oh, I forgot to mention... the turbo spools up much quicker with a operating CAT.
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Last edited by Emission; 02-11-2005 at 10:40 AM..
Old 02-11-2005, 07:34 AM
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Quote:
Originally posted by Andras Nagy
What is that white stuff clogging it? It looks cellular, closed cells and all.
The white stuff is cooked metal slag (for lack of a better description). It is hard and chalky. The entire thing is pretty brittle and it will crack and crumble (rather than dent) if I push on it. The metal has been literally cooked.
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Old 02-11-2005, 07:39 AM
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I thought it might be the ceramic material that is used as part of the scrubbing process.



In any case, this may explain some of the recurring posts from some who are baffled as to why, despite oil cooler upgrades, their cars continue to run hot.
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Old 02-11-2005, 07:48 AM
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Quote:
Originally posted by RickM
I thought it might be the ceramic material that is used as part of the scrubbing process.

In any case, this may explain some of the recurring posts from some who are baffled as to why, despite oil cooler upgrades, their cars continue to run hot.
Hmmm... the honeycomb may be ceramic (but I don't think that slag all over it is). It is pretty lightweight and that would explain why it crumbles, not crushes, under pressure.

I was shocked to see how much cooler my car ran. An honest 10 degrees across all driving conditions - and that is a lot in my book.
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Old 02-11-2005, 07:58 AM
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The debri actually looks to be some type of plastic. Howvere, I'm pretty sure plastic would just break down to chared state after a short time.

From time to time I here about fuel additive or other products damaging cats....could this be such a case?
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Old 02-11-2005, 08:02 AM
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How did you gut it? With a drill?
Old 02-11-2005, 08:13 AM
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Whacky, glad you got it fixed.
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Old 02-11-2005, 08:14 AM
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Quote:
Originally posted by JBO
How did you gut it? With a drill?
I knocked it hollow with a metal rod and a hammer - brute force - and it all crumbles out.
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Last edited by Emission; 02-11-2005 at 10:40 AM..
Old 02-11-2005, 08:59 AM
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The white stuff may be oil that builds up and bakes on the monolith brick.
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Old 02-11-2005, 09:08 AM
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Upon further research:

"A catalytic converter consists of an insulated chamber containing a porous bed, or substrate, coated with catalytic material through which hot exhaust gas must pass before being discharged into the air. The catalyst is one of a variety of metal oxides, usually platinum or palladium, which are heated by exhaust gas to about 500 C (900 F, 737 K). At this temperature unburned hydrocarbons and carbon monoxide are further oxidized, while oxides of nitrogen are chemically reduced in a second chamber with a different catalyst. Problems with catalysts involve their intolerance for leaded fuels and the need to prevent overheating."

"Fouling, clogging, melt-down and breakage of the ceramic substrate inside a converter are common conditions that can cause problems. Plugging is usually the end result of a melt-down, which occurs because the converter gets too hot. This happens because the engine is dumping unburned fuel into the exhaust. The excess fuel lights off inside the converter and sends temperatures soaring. If it gets hot enough, the ceramic substrate that carries the catalyst melts. The unburned fuel may be getting into the exhaust because of a bad spark plug or valve, but an overly rich air/fuel mixture is another possibility."

I like my Turbo to run rich - apparently at the expense of my CAT.
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Old 02-11-2005, 09:21 AM
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Your pictures reminded me of something that I once saw up here at the Boston Museum of Science.

A Healthy Lung:


A lung with emphysema:


Finally; This is a larger squamous cell carcinoma;


The moral of the story? You should no more be burning gas in your cats then tobacco in your lungs.

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Last edited by jluetjen; 02-11-2005 at 11:15 AM..
Old 02-11-2005, 10:49 AM
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Now replace that new cat with the gutted old one and just slap the new one on every two years for inspection.
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Old 02-11-2005, 02:36 PM
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the 'deposits' look to me like they were formed by accretion - or by a process that involved heat-induced alteration to pre-existing 'jaggy' deposits.

Anyway - does not look good....
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Old 02-11-2005, 05:18 PM
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See, California's smog laws are good for something. Without it, you'd still be driving around with a clogged cat!

Same thing happened with my 535. When it failed the last smog test, I could tell right away from the numbers it was the cat. Just sucked it up, spent the money for a new one the next day, and retested and passed the smog with flying colors a few days later.
Old 02-11-2005, 06:42 PM
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Quote:
Originally posted by SoCal911SC
See, California's smog laws are good for something. Without it, you'd still be driving around with a clogged cat!
Um... OK, I will give you that. ONE, just one upside.
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Old 02-11-2005, 09:35 PM
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Did you use an aftermarket cat? If so, details?
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Old 02-12-2005, 07:28 AM
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I would also like to see an answer to scottb's question, plus I have a couple more. How many miles are on your current car? Did you notice any performance or acceleration improvements with your new cat? I know you said it runs about 10 degress cooler.
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Old 02-12-2005, 01:18 PM
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Hi.

It's just a melted cat. I've seen couple of those. They will melt from lean or over-rich condition. Just install a new one and buy LM-1 wide-band thingie from Wayne so you can check you're inside the envelope (so it won't happend again).
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