Exhaust 230TE

[Beesestate]

An interesting problem: I have an early '92 230TE, one of the first vehicles to be fitted with a catalytic converter. Legally it does not need a CAT. The cat is rattling in its box and I don't want to go to the expense of fitting a new cat. There is a front pipe available without a cat (late '91 model). Question: If I were to fit the front pipe without a CAT and welded an oxygen sensor tapping to the front pipe, would this satisfy the engine management requirements. Has ahyone sufficient knowledge? Has anyone tried this?

 

[Ade]

Hi Beesestate

Are you sure it's not just the shield around the CAT that's loose.

I have a similiar problem on my '91 230TE and have decided to cut the shield off (when I get round to it!).

Ade

 

[flyingtech55]

Hi Beesestate

The answer to your question is yes. Remove the cat. and have a small box welded in its place or fit a complete new catless front pipe with the threaded adapter fitted for the Lamda sensor to screw into at the same distance along the pipe as before. The engine management system will be quite happy with that. I've done the former with my 190E. It had a terrible rattle and I thought it has the outer shield so I removed it, however it still rattled. I had the cat removed and the small box put in instead and then had a look at the cat. It had been overheating (due to overfueling due to worn injectors) and had come loose and was beginning to break up.

You can't do this on later systems because their is another sensor downstream of the cat and if you remove the cat it will trigger an engine fault.

I'm off now to get prices for new injectors.

 

[Ade]

I would be very wary about removing the CAT. This may affect back pressures (and hence engine performance) and possibly emmission control and the car's ability to pass it's MOT. I would investigate this with Mercedes first to see whether you car was a CAT option at new and whether removing it will cause any problems.

I'm not overly keen on removing the shield as this will expose the CAT to te elements more and hence hasten its eventual demise.

My exhaust is as clean as a whistle so the CATs still working. Check your exhaust for cleaniness before removing. It may prove to create more problems than you solve by removing it, especially if it's working.

The motto is 'if it ain't broke, don't fix it'.

 

[paulcallender]

I agree; leave the cat there, even if it means spending the £££ to replace it. After all, the cat is there for a reason, think of all the trees, and the fishes in the sea....

 

[Beesestate]

230TE Exhaust (thanks to all for the information)

Thanks everyone for the info. It may help you to know that the heat shield does rattle (badly corroded at welds) but this particular rattle is the cat rattling inside its box. The replacement front pipe without cat has an expansion box where the cat is, so I figure that if I weld a sensor tapping in the same position as previous it should work. I will check with Mercedes technical but I fear that they will not be too helpful. Keep the answers coming!

Regards
Beestate

 

[Ade]

Paul

I wasn't thinking environmental, I was thinking performance! Who wants a Merc that can't do what it says on the tin and can't get an MOT (like my *******!!!!!!!)

Ade

 

[paulcallender]

Well, I was being semi-serious. I agree regarding the possible changes in back pressure, could make your performance worse.

I had a quick look on www.ukmot.com and although it has the MOT testing manual, I couldn't find the flowchart which explains when a cat or non-cat test is applicable. So, to be safe, have a cat!

This might sound a bit funny, but it might be worth having a chat with the MOT tester, before you take away the cat. Even if the rules say no cat is required, if he/she decides one is, then its a fail. You don't want to start wars with an MOT tester, on a 13 year old car.....

 

[flyingtech55]

Hi Beesestate

You can remove the cat. with no bad effects on the engine management system. The cat does not/should not produce back pressure. Back pressure is produced mainly by the silencer boxes. The cat is designed to be free flow. However, as the cat ages it gradually becomes blocked and so produces back pressure for which the engine management was not designed. In fact, it is not uncommon for cats to have to be renewed because they are blocked and are choking the engine on modern cars. To put my money where my mouth is, I have done exactly what you are proposing on my 190E. I have replaced the cat with a small stainless expansion chamber. The lamda sensor stays where it is and the car runs absolutely fine, just as before, in fact very, very slightly better. The only precaution I took was to go to the MOT garage with the engine and chassis number and get them to check in their book that my car was not required to be cat tested. It's not because it was made before the !st August 1992.

The shield is not to protect the cat, but is designed to prevent the hot cat from setting dry grass etc on fire if you happen to park the car in long grass. The cat casing is made of stainless steel and will not rust. The shield welds corrode because of impurities produced by the welding process.

The cats on these older cars made almost no difference to the emmisions; they reduce the emmisions by half of one per cent. They were fitted to satisfy the regulations and for the Californian market where they stand half a chance of working because of the ambient temperature over there. Its generally too cold over here and the cat is too far back along the exhaust system. Modern ones (which do actually work) are much closer to the exhaust manifold.

For the benefit of the tree hugging, muslie eating, sandle wearers among us, to do your bit for the environment all you need to do is not fly to Spain (or where ever) in a passenger airliner. One trip to Spain and back burns more fossil fuel, produces more CO2 and more particulates than you will produce in a lifetime of car driving. More natural habitat is being destroyed by house building on green field sites for the benefit of people protecting their pensions than you will ever damage by driving. More damage is done to fish by women taking birth control pills and excreting the hormones into the water supply and making fish into hermaphrodites than a couple of converted Mercedes will ever do. More rain forest trees in Brazil are being burned in power stations to produce electricity and doing more damage to the global climatic eco-system than you will ever do. To say nothing of the environmental cost of actually mining, refining and producing the rare metals to manufacture a new cat to replace to old one. Even worse, environmentally speaking, is replacing a well maintained old car with a new one.

Hope this helps,

Gliderman

 

[stwat]

For the benefit of the tree hugging, muslie eating, sandle wearers among us, to do your bit for the environment all you need to do is not fly to Spain (or where ever) in a passenger airliner. One trip to Spain and back burns more fossil fuel, produces more CO2 and more particulates than you will produce in a lifetime of car driving. More natural habitat is being destroyed by house building on green field sites for the benefit of people protecting their pensions than you will ever damage by driving. More damage is done to fish by women taking birth control pills and excreting the hormones into the water supply and making fish into hermaphrodites than a couple of converted Mercedes will ever do. More rain forest trees in Brazil are being burned in power stations to produce electricity and doing more damage to the global climatic eco-system than you will ever do. To say nothing of the environmental cost of actually mining, refining and producing the rare metals to manufacture a new cat to replace to old one. Even worse, environmentally speaking, is replacing a well maintained old car with a new one.

Well said that man

 

[kiwi_bloke]

noise

was your 190e (pressuming 2.0) any louder after removing the cat? Reason being i got told removing that cat will make the car noisier but will hold a 5 hp gain...

 

[flyingtech55]

Hi Kiwi_Bloke

Good question. I took the car to a small, local company who specialise in handmade stainless exhaust sytems for cars, boats, aircraft etc. The chap who did the job said he could replace the cat. with a section of stainless pipe or with a small expansion box. The pipe option was cheaper; he said it would release a bit more power but would make the exhaust noisy. The expansion chamber option would reduce the power gained by removing the cat. but the car would be no noisier than with the standard set-up.

I chose the more expensive expansion box option and I'm very pleased with the result. The car is much quieter now because the rattle has gone and the engine has noticably more torque. I don't know whether the engine is improved over the original spec. or whether it is simply restored to how it should be because the cat. was old and breaking up and impeding the gas flow. I knew the cat. was failing when I bought the car. I've renewed the complete exhaust system from the front pipe back (with the standard off the shelf system) as well as the air filter so the engine is breathing as it should. It really runs beautifully, incredible for a twelve year old car with 150,000 miles on the clock. What's also incredible is that all the parts I've needed so far (albeit not that many) have been available off the shelf.

Hope this helps.