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Catalytic converter problem!

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Old Feb 16, 2010 | 09:03 AM
  #1  
chrlbake's Avatar
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2009 C350
Catalytic converter problem!

Hey Guys, last year I posted on here about an exhaust noise coming from beneath the passenger seat area/under gearbox. It happened after I was stuck over in a foot of snow. There was some speculation that this was caused from hot exhaust being packed with cold snow.... causing welds int he catalytic converter or just somewhere in the exhaust to break. From outside the car, there really is no noticable problem, just loud on the inside, especially when the car is cold and worse when it is colder outside.

Basically, I think I need a new catalytic converter/ cat back exhaust maybe. Does anyone have a stock exhaust they would be willing to sell?? I drive a 2005 230 SS, but would actually prefer the 2006 or 2007 exhaust.

I live in Indianapolis, IN and would also be willing to pay someone for their time/expertise to help me out with this!
THanks for reading!
Chris
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Old Feb 16, 2010 | 11:52 AM
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MBfinatic's Avatar
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e36 318i, 2004 sti
is there a rattleing noise when you accelerate?
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Old Feb 16, 2010 | 12:21 PM
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Why not just take to to an exhaust shop and have them re-weld it for $20?

It would save you a ton of time, money, and aggrivation if its simply a busted weld.

Plus, if it's not a broken weld, they might be able to tell you what it is and save you from throwing parts at the problem.
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Old Feb 16, 2010 | 01:01 PM
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wouldn't the broken weld be inside the converter and not reachable? Also, i've taken it to 2 dealerships and a mercedes service shop and they couldn't figure it out. Said I had to wait until it got worse. If i could get a used stock exhaust, I would jsut swap it all out..... It has to be coming from somewhere at either the cat or back..
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Old Feb 16, 2010 | 02:04 PM
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just remove ur secondary cats. if that is the problem.
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Old Feb 16, 2010 | 04:43 PM
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if i remove those then wouldn't i have to weld a pipe in its place?
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Old Feb 16, 2010 | 05:03 PM
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yep. shouldnt be to hard. I had it done a couple months ago.
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Old Feb 17, 2010 | 05:22 PM
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From: Central Indiana
2002 c230 coupe
Originally Posted by chrlbake
Hey Guys, last year I posted on here about an exhaust noise coming from beneath the passenger seat area/under gearbox. It happened after I was stuck over in a foot of snow. There was some speculation that this was caused from hot exhaust being packed with cold snow.... causing welds int he catalytic converter or just somewhere in the exhaust to break. From outside the car, there really is no noticable problem, just loud on the inside, especially when the car is cold and worse when it is colder outside.

Basically, I think I need a new catalytic converter/ cat back exhaust maybe. Does anyone have a stock exhaust they would be willing to sell?? I drive a 2005 230 SS, but would actually prefer the 2006 or 2007 exhaust.

I live in Indianapolis, IN and would also be willing to pay someone for their time/expertise to help me out with this!
THanks for reading!
Chris
WOW very ironic!! I have the same exact problem after taking it to many shops around town Here in Indianapolis,IN I've been trying to figure my problem out and mechanics have told me that i have to wait till it gets worse also.. I am also going to be looking for new CAT.. I would have it taken off but here in Indiana but i am pretty sure it is illegal to have them off so no shop will do it ...

And CHRLBAKE if you find someone around here willing to do some welding on the side please let me know , I am also willing to pay for service thanks!
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Old Feb 17, 2010 | 05:26 PM
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Originally Posted by MBfinatic
yep. shouldnt be to hard. I had it done a couple months ago.
JW you said you had this done a few months ago.

Were you having similar problems? and did it take care of it?
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Old Feb 18, 2010 | 07:41 AM
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I dont believe that there are baffels inside of the convertor that would cause any loud exhaust noise if they were damaged. The cat is just a "resevoir", so to speak, with a catalyst material inside of it. They could cause a rattling sound.

What kind of noise is it?
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Old Feb 18, 2010 | 09:02 AM
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Originally Posted by Smallbodybenz
JW you said you had this done a few months ago.

Were you having similar problems? and did it take care of it?
no the problems were not similar. i only removed the secondary cats since they dont have 02 sensors and the left one was rattling really bad.

Last edited by MBfinatic; Feb 18, 2010 at 12:00 PM.
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Old Feb 18, 2010 | 11:17 AM
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From: Central Indiana
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Originally Posted by SickSpeedMonte

What kind of noise is it?
It sort of sounds like an exhaust leak.. I hear it right underneath my seat. I especially hear it when i accelerate really fast. The best way i can describe it is when you put a baseball card in a bike wheel, just like how we all use to in the day. haha

And as long as there is no O2 sensor after or at the CAT there shouldn't be a CEL light on if i remove the CAT right?
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Old Feb 18, 2010 | 11:59 AM
  #13  
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yes sir. ya u can hear it a lot when u accelerate. there are 2 sec cats. just find a shop and have them put on a straight pipe. there wont be a light and u will still pass inspection.
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Old Feb 18, 2010 | 02:39 PM
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does anyone have any pics of the exhaust and point out what should be replaced with a pipe?? I don't have jack stands at my house here, everything is down in south carolina at my parents... therefore i its very hard for me to even see the exhaust and that makes it hard for me to diagnose where the source of the problem is. I just think it has to be exhaust related....
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Old Feb 18, 2010 | 05:31 PM
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From: Central Indiana
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Catalytic converter problem!-m111-exhaust.gif
Basically what im planning on doing is removing the CAT (#20) from my exhaust and then getting a straight pipe back.. The only prob is that in Indiana im pretty sure it is illegal to remove the CAT (#20) so im looking for a shop that may do it on the side. Should not be no then 50-75 dollars total
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Old Feb 19, 2010 | 04:49 AM
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Originally Posted by chrlbake
does anyone have any pics of the exhaust and point out what should be replaced with a pipe?? I don't have jack stands at my house here, everything is down in south carolina at my parents... therefore i its very hard for me to even see the exhaust and that makes it hard for me to diagnose where the source of the problem is. I just think it has to be exhaust related....
Try driving one wheel on a high curb or bank then you should have enough room to crawl under & inspect your cat.
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Old Feb 26, 2010 | 02:38 PM
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I went to muffler shop to get my cat removed because of the noise it was making and they said they could do it but it would cause a CEL to come on due to a O2 sensor after the CAT..
Im not really wanting to deal with that so i opted out so....

Im really stumped, i really cant see my self buying a new exhaust. Does anybody have any suggestions or solutions thanks!
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