Catalytic Converter Replacement

[AussieZ3]

My Z3 had an exhaust rattle at low speeds, which was diagnosed as coming from the catalytic converter. The only option I have here in Australia is to weld a new universal cat to replace the original unit as genuine catalytic converters are not available with BMW. I ordered a direct replacement cat on eBay manufactured by EEC in the UK and it arrived in Sydney within 5 days. Last weekend I replaced the catalytic converter and the following photograph shows a comparison between the two.



The EEC cat (eurocats) is smaller than the original and shape of the inlet pipe is different. Apart from these changes, it appears to be good quality and fitted very well. The exhaust rattle has gone but the beat has slightly changed. I would like to hear from other members who have installed replacement catalytic converters.

 

[Aceman]

Nice one, that looks like a well made system and should hopefully last the life of the car now.

 

[GazHyde]

*sighs* this is on my list of things to do. Got the dreaded CAT rattle on mine, so will be following this thread with interest. Not sure which way to go on mine, as my exhaust is original and has done 103k miles so probably may as well do the whole thing.

Was really helpful to get the side by side picture of the two . Was there much difference in weight?

 

[jonco]

Changed my `rattler' ~ 3 years ago with a budget version ( 1 year guarantee) with similar slimline shape to your photo. It's still quiet but CO emissions are now above UK limit and we think it's the cat at fault. Replacement will be needed for next MOT ( annual test in UK).
Have you had emissions checked? What are the rules in Oz?

 

[AussieZ3]

After placing the order for the cat I wrote to EEC to obtain further information. It is made to the same design as the original BMW unit with ceramic substrate and rare metals. I asked this question as some manufacturers produce a high flow cat with all metal construction. Also the EEC cat is made with stainless steel grade 409 (recommended stainless steel for exhaust systems) and it has a good finish. When I checked there wasn't a noticeable difference in weight between the two. Here in Oz, we don't have an emission test as part of the annual inspection. But they inspect the exhaust system for leaks and any signs of tampering of the cat.

 

[Barry Gadd]

I got an identical replacement cat for mine about 6 weeks ago.The earlier one looked the same. My car passed the emissions test then blew a radiator.The cat only cost around 80GBP so I doubt it will last too long
I wonder if there is any way we could treat the old cat to get it to function again?
Mine doesn't rattle so presumably it is still firmly located internally. I wonder if there is anything we could blow or pour down the pipe to bring it back to life?????
Also is there any way we could test the thing without taking it to the test centre? There must be a sensor with a measurable output. Anybody got any knowledge of how to do it??

 

[zedonist]

You cant treat them Barry, unlike a DPF filter, a Catalytic converter is exactly as it says it contains a catalyst which helps a chemical reaction without being changed or used itself, unfortunately, they get spoilt by fuel and can break quite easily from sharp knocks, hence the rattle, because they contain rare metals you can get money back at a scrap yard for them.

 

[pgunter]

I was thinking this might be something I would try myself. Anybody got any feedback regarding this type of treatment ?

http://www.amazon.co.uk/Cataclean-Catalytic-Converter-Cleaning-Treatment/dp/B002BVXM92

 

[t-tony]

The type of cat Aussie has is a very cheap replacement which will probably fail the M.O.T. Emission test at 1 year. Cats for these older cars do not have to be "Type Approved" which means they can be manufactured to a very low quality. The size of the cat is the main clue, they just aren't big enough to do the job for any length of time, just enough to clear the 1 year warranty. Sad but true.

 

[AussieZ3]

I have not come across Cat Converter rattles on other European cars before. In fact the rattling cat was the subject of a recall in the US in year 2001. The following recall notice confirms that an improved cat converter was developed in response to the fault. Unfortunately the recall only applies to US specification cars delivered in the US and BMW appear to have totally ignored the plight of the BMW owners overseas


I agree that the replacement cat I purchased may be a cheap unit but it has a 2 year guarantee. There are several other cat converter manufacturers in the UK and all of them produce both with and without Type approval. As I understand, Type approval for cat units is required for cars registered after 2001 in the UK and in Oz after 2006. This could be the reason Euro spec cars do not have an oxygen sensor post cat. All US spec cars have two sensors whereas the Euro spec cars only have one. The original BMW cat fitted to US models is different to the cat fitted to Euro spec cars. The difference I believe is the quantity of ceramic and rare metals. - Kith

 

[AussieZ3]

Does blowing of Barry's radiator got anything to do with replacing the Cat? I cannot think of a connection. -Kith

 

[ge45ton]

I had a patent cat fitted 2years ago which recently failed the MOT on emissions, the warranty was for two years so after some heated discussions it was changed free of charge. Don't expect any cheap cat to last anywhere as long as an original, 9000 miles and mine was b#ggered. Whatever they guarantee is then that's about as long as it'll last,