Catalytic Converters

[Hooty]

So what can cause a catalytic converter to fail? And is it possible to tell just by doing a surface temp check at a muffler shop? I've heard running overly rich (like I am now) can ruin them? how much does that take to ruin them? a day or two, or weeks or months? I have to replace my cat according to a muffler shop and I'm just curious since they told me it was bad just based on the temperature of it being way too cold even after about 30 minutes of me driving around. So, any good references to info about catalytic converters? advice? etc? Thanks All

-Will
89 Lebaron 2.5L T1 A413 - lightly modded

[riceboyler]

I previously owned a Volvo 740 Turbo Wagon (honestly, I still miss that car, it got me hooked on boost) that had a clogged catalytic converter in the space of 3 days due to a spark plug wire melting through. It got so hot it actually caught the undercoating on fire, and I had to stop at a gas station (asway from the pumps) and put out the fire with an extinguisher.

They can clog quickly. Are you in an emissions testing area? If not, get rid of it. If so, use the opportunity to upgrade to a high-flow cat (like a Catco or a Magnaflow) and larger exhaust.

[cordes]

Well, I thought they got really hot when the failed. As previously stated if there is no inspection in your state, I would ditch it. They only cause a longer spool up time. YMMV.

[JDAWG]

I always thought they got really hot too. The right way to do it is flow check it before and after the cat. Yes running rich will cause a cat to get clogged but depends on too many variables to say how long it will take to clog.

[3Bar_Mopar]

I have to replace my cat according to a muffler shop and I'm just curious since they told me it was bad just based on the temperature of it being way too cold even after about 30 minutes of me driving around.

-Will
89 Lebaron 2.5L T1 A413 - lightly modded


From what I understand....when they go bad the get very HOT because they cause a huge restriction in the exhaust flow. As far as I know, when they are cold they aren't doing their job fighting emissions since the catalyst needs to be somewhat fairly warm (cat light-off) to do it's job.
I think your rich mixture is causing cooler exhaust temps and not lighting off the cat like it's supposed to....probably playing havoc on the catalyst element too, it will clog if you don't fix your rich mixture.

[Tony Hanna]

I have to agree with everybody that says ditch it if you can get by with that.
My situation is a bit of a strange one in that we don't have e-checks, but do have to pass a visual inspection. To get around this, I usually run an empty(gutted) converter shell.
I think your main concern at this point should be finding and correcting whatever's causing it to run rich. The price of gas alone should provide good motivation, but there's also the chance of engine damage due to cylinder washdown and gasoline thinned oil.
HTH

[slm90vnt]

So what can cause a catalytic converter to fail? And is it possible to tell just by doing a surface temp check at a muffler shop? I've heard running overly rich (like I am now) can ruin them? how much does that take to ruin them? a day or two, or weeks or months? I have to replace my cat according to a muffler shop and I'm just curious since they told me it was bad just based on the temperature of it being way too cold even after about 30 minutes of me driving around. So, any good references to info about catalytic converters? advice? etc? Thanks All

-Will
89 Lebaron 2.5L T1 A413 - lightly modded
Way to cold? I would think that would be a good thing. I always thought they got hot if they were restricted.

[87glhs232]

The gas conversion has a specific temp range. Really quite narrow, only 150 or 200 degree bracket around 500 (i think). If it's to cold, thats bad, it's not converting. But not as bad as a clogged cat thats building restriction and heat.
You can take it off and look down through it. You should be able to see light through a couple layers of honey comb. If not, your clogged.
Cats only have a 2-3 year life span for cheap ones, 3-5 years for higher quality and more expensive ones. They're supposed to be regular maintainance items. What causes them to fail? The elements that are used to convert the various gasses eventually are 'used up'. Add carbon build up and......well you see.

[turbovanman²]

Wow, alot of bad info.

First off, OEM cats are very durable, hence when you price one out, you sh@t yourself.
A cat converter is that, its a catalyst and doesn't get used up as stated, a catalyst is a substance that causes a chemical reaction but doesn't get used up in the process. What happens over time is oil, carbon, being overheated will coat and melt the substrate causing it to lose its efficiency and finally stop working.
Cats do get warm and they start to work but I never judge a cat by heat in and out, I have done numerous tests on this-I am an emissions technician, and its very inacurrate. THE only proper way to test a cat is to do a before and after test, you sample the gas's going in, it should light off from cold in 90 secs, then compare to the gases going out. If its 80% or better, its ok.

Now, you can kill at cat in hours, days or weaks. Misfires and mega over fueling will kill it very fast as the cat will glow red and start to melt. If its not to rich, they can still live. I put a supercat on by Walker on a customers truck 2 years ago, last year, his carb screwed up and its was running at 8% CO for a year, he brought it in, I fixed it and the cat is still alive. The cheaper the cat, the shorter it lasts. Looking at the catco's, I think there cheap and thats why I use Walker Supercats, thats what i have on my van and it cut a bit of power, just barely noticeable. As for life, I have seen OEM's last 10 years or more, again, it all depends on how the car/truck is treated. If its given regular mainenance and doesn't burn oil, the converter will last. The OE's are supposed to warrant them to last 100,000 km's or 5 years. Again, by a cheap one, it won't last, I do this if they don't want to spend money and average span is 1 year.

I hope this clears up the ways of converters, :thumb:

[Lee'sdaytona]

hmm....back when I had a new cat put on, like 2 years ago...I think it cost like $200....not sure which brand either....I don't think they wrote it up on the form and back then I really could care less. but I wonder is that a cheap one or a good one? I know for my dad's subaru forrester, it was like $500 OEM, but thats a much newer vehicle....
-Lee

[Hooty]

I'll see what I can do (dang it I hate apartment living), as for needing a Cat, yeah, the portland area requires it, so far as I know with the e-check, if the number of "tampering with a Catalytic converter can cause large fines injury and even death" signs in the muffler shop... Lol, anyone know a reputable shop in the Portland Area that knows TD's?

-Will

[turbovanman²]

I'll see what I can do (dang it I hate apartment living), as for needing a Cat, yeah, the portland area requires it, so far as I know with the e-check, if the number of "tampering with a Catalytic converter can cause large fines injury and even death" signs in the muffler shop... Lol, anyone know a reputable shop in the Portland Area that knows TD's?

-Will

Find Gasketmaster on Turbododge-his name is Terry Ryan, he's a turbododge shop in Portland, among other things. :D

[Hooty]

Already did, he's more in to the Race Car component of things, than fixing common daily drivers, at least from what he indicated to me. Well, I still have my old O2 sensor, uncut etc. Maybe I can try that out, my brother is finally going to help me out and let me work on it at his house tomorrow probably, so I can at least check the injectors. Depending on what my day looks like I will probably try to get that old 02 sensor put in (only changed it out because of some rough Idle issues that were caused from a broken wire to the Map sensor. Don't think it was really bad).

-Will
"Now where did I put that part?"

[Hooty]

If its given regular mainenance and doesn't burn oil, the converter will last.

Well,
I burn oil, about 1 quart every oil change, which I don't think is too terrible, at this point at least (I've had the car where you stop at the service station to check the gas and fill 'er up with Oil).

-Will
Watch the evil hypnotic bowling ball very closely!!!!:bowl:

[87glhs232]

Contact Johnny at Polybushings.com. He works a day job at a shop right off of 84 between 5 and 205. Across the street from Graybar. Forget the exit thought. I think its on 60th or something. They may be able to help, or Johnny might know of someone.

EDIT: NE 60th and NE Holladay St :p

[turbovanman²]

I mean Hooty, is ask Terry, he can point you in the right direction, :thumb:

[Hooty]

Sounds good, BTW, ever have that feeling that your car hates you??? I really think she dislikes me fixing her. I just pulled codes on her *again* this morning, before, I swear there was nothing wrong, now, code 52 - O2 sensor indicates rich too long. I guess since I didn't see any little golf carts running around, time to sneak out under the hood. Maybe going to switch back to my old O2 sensor if I can work the timing on it.

-Will

[mech1nxh]

turbovanman Wow, alot of bad info.

. THE only proper way to test a cat is to do a before and after test, you sample the gas's going in, it should light off from cold in 90 secs, then compare to the gases going out. If its 80% or better, its ok.

actually , good points and some incomplete points.....
I am going to put together a concise procedure for cat diag
as this issue comes up very often....
a simple list as follows..(will elaborate after the holidays)

1)temp test
2)0/2 "snap test"
3) C/O H/C ratio test
4) " intrusive test"...ratio in /ratio out(and some other variables)
emissions repairs/diag and myself are very old friends..... (C.A.
unlimited smog test and repair license since' '86 , doesnt make me special,)


BUT... for now , plus 1 for all the advise on finding a good shop,
P.M. me and I can help you real time if you have an urgent need to
resolve an regristration/sale issue.....

best of the season to all........MECH1NXH

[Hooty]

Awesome amount of feedback on this guys, thank you so much for the information!

-Will

[Whorse]

Correct me if I'm wrong, but I've heard that if you ever run alcohol in your tank, or any kind of engine cleaner, it hurts your exhaust system because all the carbon buildup being burned off or cleaned gets into the exhaust and then cools as it passes through the system.

I know that on my car after I blasted the intake with carb cleaner that my car seemed to run a little richer, which could be that I hurt an already going O2 by doing that.

Your books have anything to say about that Simon? I'm hoping to fix this up on my car soon as well.

[turbovanman²]

Correct me if I'm wrong, but I've heard that if you ever run alcohol in your tank, or any kind of engine cleaner, it hurts your exhaust system because all the carbon buildup being burned off or cleaned gets into the exhaust and then cools as it passes through the system.

I know that on my car after I blasted the intake with carb cleaner that my car seemed to run a little richer, which could be that I hurt an already going O2 by doing that.

Your books have anything to say about that Simon? I'm hoping to fix this up on my car soon as well.

Its the chemicals and dissolved carbon that damage the oxygen sensor. There really very fragile units and are easily damaged. Its quite possible you did damage it. I would disconnect your battery after you've cleaned it and given it a thorough thrashing. After cleaning, you need to reset the computer-they do learn a little bit and this needs to be redone after a major tune-up, component replacement or cleaning.

[WVRampage]

I have a rampage and the cat burnt up on it long ago, I got a short glasspack and put it in place of the converter and even welded the sheild from the converter to it so it will pass the visual and with the glass pack it doesnt hurt the flow but it doesnt kill your ears on the hiway.