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I have an '01 ML320 that I just discovered a right cracked catalytic converter, and the left has a h

  • Left cat bad

    Votes: 0 0.0%
  • Right cat bad

    Votes: 4 18.2%
  • Both cats bad

    Votes: 3 13.6%
  • Never had a problem

    Votes: 14 63.6%
  • What's a cat????

    Votes: 1 4.5%

Cracked Catalytic Converters

2K views 15 replies 12 participants last post by  gw17625410 
#1 ·
I have an '01 ML320 that I just discovered a right cracked catalytic converter, and the left has a hairline crack starting. With 77.5k, I just slip in under the EPA mandated warranty coverage on emissions equipment... Who else has had this problem?
 
#2 ·
Mine (right side) just crapped out with 67k on the odo.
 
#3 ·
I saw one of those once...

But I know why this CAT cracked - it couldn't take the pressure!
 
#6 ·
A catalytic converter is a device in-line in the exhaust system that uses a catalyst (usually includes platinum... that's why they're so expensive!) that 'scrub' the exhaust and remove emissions gases.
 
#7 ·
'scrub' the exhaust and remove emissions gases.

That's great, so do I have one on my ML or is it optional equipment and can it be an aftermarket modification?

I doubt that I have one because I can see the exhaust coming off on the right of the spare tire, so I do have emissions gases on my '02.

Maybe it's standard in CA only because of the crazy californian laws? [:D]
 
#8 ·
RE: 'scrub' the exhaust and remove emissions gases.

All gasoline vehicles sold in the US since the early '80's have them, mandated by the EPA. California CARB regulations are even stricter than EPA, so it is possible the California ML's have other emissions reducing equipment in place. You actually have two, one on either side of the engine just beyond the headers for each bank of cylinders.
 
#9 ·
I understand platinum cleans the exhaust to keep it shiny, but if it removes the

emissions gases like you say, why do I have a hole at the end of my tail pipe.

You say it's been mandatory for years here, fine, but since it has been cold these last few days, I can definitely see emissions gases coming out of the tail pipe in the form of whitish clouds of smoke. Are you saying that my platinum is broken? Another ML defect that tcpgv will list in his posts!
 
#10 ·
RE: I understand platinum cleans the exhaust to keep it shiny, but if it removes the

tcp_ML500 - 12/12/2003 2:33 PM
I can definitely see emissions gases coming out of the tail pipe in the form of whitish clouds of smoke. Are you saying that my platinum is broken?
The "whitish" smoke you see is water vapor now that it is colder outside, and is comepletely natural. The platinum everyone is talking about is in the form of screens inside these muffler-like chambers in your exhaust. The pressure backs up in there and and is then filtered out the rest of the exhaust. Probably responsible for a 5hp loss. That is why the sell aftermarket or more performance oriented catalytic converters.
 
#13 ·
RE: The hole in the tail pipe????

I have a hole in the tail pipe too !!! Time for a recall... just kidding.

Above explanations from you guys are pretty good: yes the cat (not meow) job is to keep NOx and CO in check so that they are within EPA parameters. One of the by products from this catalyst reaction is SO2 (that's sulphuric acid) which is not good for the exhaust system.

Basic exhaust color:
White - either moisture or antifreeze leaking through
Black - fuel too rich
Blue - burning oil.
 
#14 ·
RE: The hole in the tail pipe????

Hello,
The company I work for (Johnson Matthey C.S.D.N.A.) manufactures Catalyst. There are many formulas of prescious metals but two types of catalyst substrates, Ceramic and Metal. I found on my parents 2000 ML 320 the welds of the actual can that suround the substrate cracked at 52K miles. The dealer first told my parents it was not covered. I pointed out the law and the dealer covered it.
1) The owners manual of your vehicle will state exactly how long the warranty is on the emission system.
2) The U.S. Federal government (for those outside ???) sets the minimum for these warranties. It originally was 100K miles I believe it now is 150K miles for the newer cars. This should also cover all emission related parts
Thanks
David
 
#15 ·
Thanks David...

The company I work for (Johnson Matthey C.S.D.N.A.) manufactures Catalyst. There are many formulas of prescious metals but two types of catalyst substrates, Ceramic and Metal. I found on my parents 2000 ML 320 the welds of the actual can that suround the substrate cracked at 52K miles. The dealer first told my parents it was not covered. I pointed out the law and the dealer covered it.
Thank you for your expert information on this. For what it's worth, both of my catalytic converters' welds were starting to crack as well. They were replaced about 6 months ago.

From what I have been told, the suspicion is that for the earlier MLs, the supplier didn't do a good job with the welding for quite a number of these units. If you look at the welds, they don't necessarily penetrate the gaps in the metal, therefore over time they weaken more and start separating.
 
#16 ·
RE: Thanks David...

Drew,
I actual bought my ML from the company. We were going after M/B business and J.M. purchased a E320 and the ML430. After they bought the ML, they realized we needed a four wheel dyno (which we didn't have) to be able to test it. With the cracking I am glad we did not get the business. Also, burning oil kills catalyst internally. I informed the dealer about this when they fixed my oil consumption problem. The SA response was the ussual "did not know that, and we have not had any problems with the converters". When I saw this posting. I wondered if people meant the welds or if the vehicles were failing emissions test. If it is the later and the engine is using oil that is why.

I am not sure of your back ground but I noticed you run the forum. My first post was about oil consumption. Surprisingly to me, it seems as though no-one has heard of this problem, and has yet to answer my question. Are you familiar with this problem and what causes it.
Thanks
David
 
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