Unofficialbmw.com

[walshja]

has anyone changed the cats on an E39? my inspection is due, and mine need to be replaced ASAP

is this a DIY job? doesn't look too hard, just looking for some feedback from someone who knows.

thanks
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joe

1994 325iC, 195k miles
http://home.comcast.net/~walshja/index.html <--- check it out

[edjack]

THere are two options. Replace the pipes and converters with an OEM assembly. Bolt-on job. Note that, if you twist off the mainfold bolts, they are about $30 each.

Have a pair of "universal" cats welded in.
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Ed BMW CCA member since 1987 (Nr. 62319).
'97 540i 6 speed Aspensilber over Aubergine interior.

[walshja]

hey Ed

I found these bolt on replacements
http://www.ultimategarage.com/shop/part.php?products_id=2236

just wondering if it's an easy DIY job, or if I should have a shop do it.

in reading up on this, sounds like I need to raise the engine 1/4inch, drop the entire exhaust, then replace the cats.

the dropping of the exhaust is what's giving me concern.

have you ever done this? do I really need to drop the exhaust and raise the engine?

thanks for your help !!
_________________
joe

1994 325iC, 195k miles
http://home.comcast.net/~walshja/index.html <--- check it out

[edjack]

Never have. Talk to your local muffler shop.
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Ed BMW CCA member since 1987 (Nr. 62319).
'97 540i 6 speed Aspensilber over Aubergine interior.

[edjack]

Bentley says to raise the engine. I would think that you could remove the nuts on the manifolds, and lift them off the pipe, w/o dropping the exhaust system.

BTW, how do you know you need to replace them? Are they rattling? Sometimes a defective post-cat O2 sensor will trigger the code. Be a good idea to replace them first, and see if the problem goes away.
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Ed BMW CCA member since 1987 (Nr. 62319).
'97 540i 6 speed Aspensilber over Aubergine interior.

[walshja]

had not thought of replacing the post-cat sensors.

good idea, since they are what trips the check engine light. my mechanic and dealer said the cats were bad, but I'm guessing they are basing that claim on the codes being thrown by the computer.

you helped me change the pre-cat sensors, will I have easy access to the post-cat sensors?
_________________
joe

1994 325iC, 195k miles
http://home.comcast.net/~walshja/index.html <--- check it out

[edjack]

Realoem.com shows this drawing of the cat: http://www.realoem.com/bmw/partgrp.do?model=DP63&mospid=47595&hg=18&fg=10

Is yours like this: http://www.ultimategarage.com/shop/part.php?products_id=2236 with the cats just under the manifolds?

The latter drawing shows the bungs for the O2 sensors. The pre-cat sensor looks like it's on top of the manifold, and the post-cat sensor is seen below the cat.
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Ed BMW CCA member since 1987 (Nr. 62319).
'97 540i 6 speed Aspensilber over Aubergine interior.

[walshja]

I believe this is my setup

http://www.realoem.com/bmw/showparts.do?model=DP63&mospid=47595&btnr=11_2183&hg=11&fg=50

this is last digits on the VIN ---> BV61369

wife has the car, so I can't go and see what kind of access I will have.
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joe

1994 325iC, 195k miles
http://home.comcast.net/~walshja/index.html <--- check it out

[walshja]

just an update, I never replaced my cats, and I failed emissions and now the registration is due, so I had to do something quick.

bought this product
http://www.amazon.com/Cataclean-Engine-Catalytic-Converter-Treatment/dp/B002BVXM92/ref=sr_1_2?ie=UTF8&s=automotive&qid=1283552306&sr=8-2

waited until the tank was 1/4 full, dumped the entire bottle in, maybe 50 miles later my check engine light went off. went to emission and passed !!!

I did this about a month ago, but my wife never told me the light went off, until it came back on (after a tankful of gas). so the light will come back on, but this definitely gets your through emissions !!!
_________________
joe

1994 325iC, 195k miles
http://home.comcast.net/~walshja/index.html <--- check it out