W210 Cat Rattles

[AdrianDW]

I recently purchased my first MB, a 2000 E240. Got it from a known source, so trusted, and got the full lowdown. Won't be having anything else from now on, so long as funds allow!

I understand these babies have four cats - 2 front, 2 rear (presumably one set for each cylinder bank), and I'm led to believe that the front ones give an indication of their imminnent demise by starting to rattle as the internal wadding gives up the ghost; Well, I've got this rattle building nicely now (v embarrasing driving up the road to the house I can tell you!), and it doesn't seem to be anything else.
I'm also told that these are hideously expensive to replace, but can actually be dispensed with (i.e replaced with a suitable straight through pipe), as the car is more than capable of passing UK emissions tests with the just the back two in place?
Can anybody confirm this before I
(a) Get the "remove" option done, or
(b) Remortgage house, sell fiancee etc. to finance a replacement

 

[jimmymack]

I don't know much about Merc's in general, but I am sure that your car will not have 4 cats, just the one. Genuine Mercedes cats will be reasonably expensive, try cats direct instead, I think they are about £130 or so but you do have to get them fitted yourself, or even fit them yourself.
As your car is a 2000 model you WILL need a cat to pass the MOT, things changed in 1992.
Its just one of those things.
I would make sure that the person who has been advising you about Mercedes does his homework first as it could have been quite embarrasing asking the dealer to replace all 4 cats

 

[jimmymack]

check out this link, looks like there might well be 4 cats !!!!
http://www.cats-direct-shop.co.uk/three-year-catalytic-converter.php?recordID=870

 

[tom7035]

Two of them are known as 'pre-cats'.

 

[Parrot of Doom]

My TVR had 3 cats - 1 precat for each bank, feeding into a main cat for the exhaust.

 

[Tony]

I doubt if it's the pre-cats that are rattling - it'll be one or both of the main cats. You won't get through the MOT without them and, even more to the point, your engine won't run properly without them These closed loop systems are very picky and the lambda sensor behind the main cat will throw an engine code. The Merc cats are very expensive, but watch out for the cheaper ones - some don't work efficiently enough to keep the Merc sensors happy and you'll find the guarantee is pretty worthless. There are too many ways out.

 

[AdrianDW]

Thanks for this all. Nobby went in for an A inspection yesterday, and sure enough the nice kind stealer told me the cat was gone and would I like to get it done for around £800. Assured him that I won't just yet, as £900 for the A, spark plugs, one ball joint, and half of Saudi Arabia's daily output was quite enough! Once its had the dreaded tin worm sorted out under mobilo (due in next month), i'll be going via the local indie specialist.

 

[Silver Arrow]

I thought I had a rattling cat on a different car. It turned out to be a loose heatshield over the cat.

 

[tom7035]

I thought I had a rattling cat on a different car. It turned out to be a loose heatshield over the cat.

This is certainly worth checking, very common problem.

 

[clive williams]

and, even more to the point, your engine won't run properly without them .

I had a '91 Audi 2.8 that improved immeasurably when the cats broke up and cleared the system. No change to the ECU chip either, it just coped. Power went up, the engine was smoother, the pickup smoother and lower in the rev range etc and to cap it all AT LEAST 10 % improvement in fuel consumption with a CO rating of 0.35% (fractionally above max cat standard) All this on a car that covered 174k mls!
When they produced this car Audi stated that the cats had no effect on power or efficiency - ******** ('unprintable').

Clive

500E
E320CDIT210

 

[mercmonkey]

If ur cat is dead ull smell it lol

I kid u not.... you can get some funny smells from the exhaust when the cat has expired.

PLEASE NOTE - PROLONGED EXPOSURE TO EXHAUST FUMES CAN BE DANGEREOUS
(I know we're all grown up enough to own MB's but you never know)

 

[tech lee]

Adriandw. dont leave it too long with a collapsed cat as the particles have been known to find their way back into the engine and can severly damage the cylinder bores.

 

[big x]

Adriandw. dont leave it too long with a collapsed cat as the particles have been known to find their way back into the engine and can severly damage the cylinder bores.

I think this only happens on the V6.

adam

 

[tech lee]

adrian said it was an E240 which is a v6.