540 cat

[yaofeng]

Both cat converters are removed. I found holes in the honey comb. I am replacing all bolts and nuts with stainless steel ones so removal won't be as painful. Should I get the old ones up? Or are they both toast?


The driver side cat looking at the upstream opening.


Another shot.


Yet another.


The passenger side one looking at the upstream opening.

I have the DEC on my 525. I don't like it. But the original is very, very expensive. I thought if I buy the DEC I may as well try this one on Ebay.

http://cgi.ebay.com/ebaymotors/BMW-5...spagenameZWD1V

has anyone used it?

[Tiger]

Get Magnaflow cat converter instead... these looks too small. You want to get one just as big as OEM as possible. Talk to their tech support on hoe big you can go. Why do you think OEM is so expensive? They are monster sized.

Those cats look toasted, if not tampered by previous owner.

[yaofeng]

Flow monster has the same diameter honey comb section. But it is way shorter. Thanks for the idea. I am now looking into Magnaflow.

[Bill R.]

are deeper in. Before replacing you also need to determine what caused them to fail. Cats usually fail because they overheat from raw fuel hitting them and igniting in the cat.

[yaofeng]

Since I am using all stainless steel nuts and bolts, replacing won't be that painful. Maybe I should put them up, sent the car to emissions testing and see.

[Bill R.]

to fall out the holes in the screens, if not then they are probably ok and the screens just have holes in them.










won't be that painful. Maybe I should put them up, sent the car to emissions testing and see.[/quote]

[Jr ///M5]

You better re-think the idea of using stainless steel bolts. The regular bolts with copper stamped nuts are on there for a reason. The stainless will gauld once heated and you'll never be able to remove the nut. You'll be forced to cut the bolt. Ever tried to cut a stainless bolt?

Do what you see fit, I'm just warning you.

[yaofeng]

I am not touching those copper nuts on the headers. They have been installed. The bolts with serrated shank I removed are grade 10.9, no copper whatsoever.



Ever try to remove rusted shut carbon steel bolt and nuts? I'll take stainless steel bolts and nuts any day.