Hi folks,
The CAT on my 1994 220 petrol C class with approx. 100000 miles on the clock, has started rattling when cold on tick over and is noisy at high revs so it appears that the ceramic core is breaking up. While enquiring about the price of a replacement, the exhaust retailer implied that they had sold a number of this model recently and that I should have the car checked for over fuelling as this is the reason for the existing CAT failing and that a new one would not last long unless the fuel problem was fixed first. All sounds reasonable from what I then read on the web. However I have also been told that for the car to be over fuelled enough to cause the CAT to fail the car would not be running perfectly well as it does.

So my question is what are the experiences of people who own these, would I notice the car running rough if it was over fuelling enough to fail the CAT?, is there a common fault known on this model? Or have people found there CATs failing around this age on this model?, or found other causes? Although the heat shielding around the CAT is in fairly poor condition it does not appear to have been hit which is the only other reason I have herd of for failures.

As a side question purely for interest the design of CAT on this model looks like 2 tubes welded side by side with the exhaust split between them, has any one cut one up? Is it just two small round cores in there or is there more to it?

Thanks in advance for any knowledge / experiences.

Marc

WOW! My book lists this as a $1395.00 item. I'm glad mine's diesel.

Been quoted £300 including tax for a pattern part, expensive enough that I don't want it to go again in a hurry.

Marc

if your car is over fueling,it probubly runs better. it would have to be really rich to notice a problem.
good luck rich

__________________
88 300E White, sold 9-04
88 190E Black 2.3 sold
90 300CE White, Grey sold 12-24-04
92 400E White,Grey Sold 5-06
90 300CE 91K Signal Red,Black Sold 2007
1989 300CE Smoke silver,Tan Sold 1-08
1993 300E 3.2 M104 motor
1991 300CE White,Grey
1994 E420 beautiful car,gone to new home
1994 E320 Smoke an Parchment.Beautiful car

My 1994 Euro C180 was troubled with this loud rattling exhaust late 2002 and I had it changed. The indie changed all OEMs except the cat which was local and costed much less than the OEM part. He told me the rear exhaust was crap(insides gone) and the cat was also crap(insides gone). The new setup is very nice, but the exhaust sound is not as quiet as I would expect from a close to luxury car, sounds too burbly. I saw a C200 or C220 which had such a smooth sounding engine and exhaust I couldn't believe it. It purred softly and growled smoothly when stepped on, unlike mine. Anybody? Mileage is now 196,000kms.

Hocky, did you find any reason for your original CAT breaking up. What concerns me is being told that if I change it without finding a reason for it breaking up then the new one is likely to do the same.

Marc c

Marc c, I don't know what happenned to my original cat because the indie was only too interested in changing the whole set which costed me a huge sum including labour. Something like A$800 to 1000. Could have been more, but he also did other necessary things too. I can only guess that it was caused by high speed driving on highways without speed limits. I cannot think of any other type of abuse. Maybe some saloon racing also. This car looks like it has not been modified, but when you step on the acc, sometimes it goes like the hell and makes a loud roar. Oh well its only 1799cc!

Hocky, well at least it looks like some times they just fail and replacing the CAT without finding anything else wrong does not always mean that imminent repeat failure is going to occur. As you have had yours fitted for a while now, I think it would have shown up if any thing was going to cause a repeat failure. So perhaps I am just being paranoid! Any one else got experience of CATs breaking up for known or un-known reasons.

Marc c

imho oe cats last a long time.they sometimes break because of very rich conditions or impact.
but the codes you got were not for running rich.
if you ever have to replace 02's again, just make sure that it is just the ONE 02 that is bad. two or more at one time points to a vacuum leak or mixture problem. 02's can last 200k miles. just may be a little slow.
mercedes are ment to be driven at high speed. that should not damage the cats.
a bad mechanic is more of a probem
when i see more than one 02 code on two differant banks,the odds of bad 02's are pretty slim
some thing i learned recently is that 02's loose their ground.this can be checked by clipping a temporary ground from the 02 to frame. not the exhaust. i got this from the bosch rep.
this is very true on 3 wire 02's but 4 wire also. does that me module control the ground side?
well got carried away again, sorry about the long post
good luck rich

__________________
88 300E White, sold 9-04
88 190E Black 2.3 sold
90 300CE White, Grey sold 12-24-04
92 400E White,Grey Sold 5-06
90 300CE 91K Signal Red,Black Sold 2007
1989 300CE Smoke silver,Tan Sold 1-08
1993 300E 3.2 M104 motor
1991 300CE White,Grey
1994 E420 beautiful car,gone to new home
1994 E320 Smoke an Parchment.Beautiful car