catalytic converter symptoms

[clelly]

Can anyone tell me if there are characteristic symptoms to look out for, or to listen out for which indicate your catalytic convertor is about to give up?anyone any idea of the lifespan of a typical merc exhaust system,will the cat give up before the exhaust does?
Thanks

 

[peterchurch]

Can anyone tell me if there are characteristic symptoms to look out for, or to listen out for which indicate your catalytic convertor is about to give up?anyone any idea of the lifespan of a typical merc exhaust system,will the cat give up before the exhaust does?
Thanks

By the time they go its too late

_But_ when my SL's went the simple answer was to cut the cat out and leave the can empty... the rest of the system took up the slack and passed an MOT by miles... it it does not then its new cat time...

 

[television]

By the time they go its too late

_But_ when my SL's went the simple answer was to cut the cat out and leave the can empty... the rest of the system took up the slack and passed an MOT by miles... it it does not then its new cat time...

From a catalyst point of veiw they last a long time, when they go they often rattle when its the bottom ones, or if its the top,then they can block the system,but really as Peterchurch say "by the time they go its too late"


Malcolm

 

[type49]

Can anyone tell me if there are characteristic symptoms to look out for, or to listen out for which indicate your catalytic convertor is about to give up?anyone any idea of the lifespan of a typical merc exhaust system,will the cat give up before the exhaust does?
Thanks

Do you have a problem with the car & not sure wether it's the cat, or are you looking to by a car but worried about future costs?

 

[clelly]

I dont really know if I have a problem or not.Sometimes when I accelerate from stop I get what sounds like what used to be called a pinking noise but that was before petrol injection so I am not sure what is causing the noise?
Equally the thought of a replacement is causing concern.

 

[television]

I dont really know if I have a problem or not.Sometimes when I accelerate from stop I get what sounds like what used to be called a pinking noise but that was before petrol injection so I am not sure what is causing the noise?
Equally the thought of a replacement is causing concern.

The car could be too far advanced and causing pinlking, what car is it.

Malcolm

 

[Ultymate]

As Malcolm says it could be over advanced ignition timing although a lot of the newer cars are not easily adjustable in this respect, by the way fuel injection is no barrier to "pinking" main causes are over advanced timing sub-standard fuel or sometimes excess carbon build up in combustion chambers will cause it. If you come back with the model and VIN number of your car I'm sure Malcolm "Television" will tell you if your timing is adjustable :wink:

 

[clelly]

Its a mercedes c200 elegenge w reg(2000) vin 202
thanks to all for their help

 

[peterchurch]

From a catalyst point of veiw they last a long time, when they go they often rattle when its the bottom ones, or if its the top,then they can block the system,but really as Peterchurch say "by the time they go its too late"

Malcolm

Just as an aside do you think that a faulty MAF could have an effect of damaging the cat converters? Mine went on my SL at about 30K and I know of at least 4 other SLs that had the issue before 40K miles (3 v6 320s and a 280 all facelifted cars) any ony seen this happen on the SL500 99-2002?

Sorry I'l but out of your topic now

 

[eric242340]

Catalytic converter

Can anyone tell me if there are characteristic symptoms to look out for, or to listen out for which indicate your catalytic convertor is about to give up?anyone any idea of the lifespan of a typical merc exhaust system,will the cat give up before the exhaust does?
Thanks

The only real way to test a Cat is by doing a backpressure test and for this you would need pressure guages, but most indies will have one. However to test the pre-cat (which is the first cat on the pipe) you would need two people. One person in the car and one to watch the pre-cat. Raise the engine speed to 2500 rpm and hold it for two minitues, if the pre-cat starts to glow red then it no use. The chances of a cat failure on models exept the ML is very small. The first sign of a cat failure/partial blockage is normally the check engine light on and if you could read the fault codes it would say 02 sensor. Appart from this there is no way to PREDICT a cat failure.

 

[FADEC]

Both the bottom cats on my CLK started to make an annoying rattling sound recently. We put the car up on a ramp and discovered the rattling was from the aft 2 cats. After a change of filling stations used i.e non supermarket fuel and a long run up the motorway the problem seems to have disappeared.

Could these symptoms be at all related to fuel used in the car? This is not in response to recent reports in the media!

 

[peterchurch]

Both the bottom cats on my CLK started to make an annoying rattling sound recently. We put the car up on a ramp and discovered the rattling was from the aft 2 cats. After a change of filling stations used i.e non supermarket fuel and a long run up the motorway the problem seems to have disappeared.

Could these symptoms be at all related to fuel used in the car? This is not in response to recent reports in the media!

No I'm afraid you sound like you have two blown cats. Its possible that
a) They got totally destroyed on your long run. or
b) They have rotated round and got jammed.

Because they are the rear ones and not the front, you may get away with getting the cans opened and removing the chuff then re welding them shut. Thats what I did with my SL in the finish and it actually worked. It was too late by then as I had got fed up and had sold the car without the one rear cat the car passed the co2 cat test 3 times over the pass mark! so you might still pass without any rear cats at all providing the car is tested hot

Out of interest I spoke to a merc dealer the other week and he suggested that very low millage cars might not be the best idea given that the cats never get a chance to really be used and may fail early as a result...

 

[eric242340]

Catalitic converters are a problamatic subject. But the only thing that effects them is the fuel/air ratio. If the mixture is wrong then they can go wrong, but it takes a long time for this to happen. However as has been said when they go wrong there is no easy fix. You can remove the innerds of the cat and fill with wire wool, but they never sound the same afterwards. Also you will spend forever trying to ge the air fuel mixture correct.

 

[television]

Also you will spend forever trying to ge the air fuel mixture correct.

Not true how can the mixture deviate having the insides removed.

My old SL ran perfectly without them as have many others here, and past the MOT

malcolm

 

[Blobcat]

I wouldn't recommend wire wool, a few bikers have tried that one to cut down on the noise. Hitting a scrutineer or MOT man in the face with a flaming ball of wire wool will always get you a fail

 

[Pipemaster]

Not true how can the mixture deviate having the insides removed.

My old SL ran perfectly without them as have many others here, and past the MOT

malcolm

Would the lack of back pressure from the empty cat change the mix temporaritly until the ECU remapped itself to compensate so any devitation in the mix would be temporary? This would clearly not be the case in non self adjusting ecu's I suppose.

 

[television]

Would the lack of back pressure from the empty cat change the mix temporaritly until the ECU remapped itself to compensate so any devitation in the mix would be temporary? This would clearly not be the case in non self adjusting ecu's I suppose.

I had no problem with my V6 SL there is nothing in the system that can measure back preasure plus you cant adjust the mixture,well you can on a 1990 or there about car, not sinse then. It would soon adjust and keep adjusting just a it did when you had a cat.

I do wish Eric would stop saying these things, putting the fear of god into people.

Malcolm

 

[FADEC]

Thanks for all the info guys. Is there any danger of the cats breaking up and a blockage occuring?

 

[television]

Thanks for all the info guys. Is there any danger of the cats breaking up and a blockage occuring?

This has been known with the upper ones,but it is the lower ceramics that rattle.

There are some very good ones on the market now in spite of what people say, I am the worlds fussiest i used some and was very pleased with them

Malcolm

 

[khanie]

2 points which may rest your fears......

1 - my de-catted 96 E230 passed its MOT on Monday without a single thing needed doing - we don't use supermarket petrol and try to put some V-Power or similar in every know and again. Other than that it's run as any other car even with 120 000 on the clock. The cat was simply cut out and replaced with a short section of stainless steel pipe. Its a bit of a bodge-job but I'm not to blame - previous owners did it!!

2 - my pinking was sorted out by replacing the MAF with a cheap generic one - about £45 from Ebay. Proper Merc ones are about £250, bosch ones about £100. I'm a cheapskate......

Hope this helps

Mark.