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catalytic converter

Discussion in 'E39 (1997-2003)' started by beemerjim, Sep 20, 2010.

    beemerjim guest

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    1997 E39 540i, Engine light on, number 2 convertor on passenger side is registering on code. The service shop that I have taken it to said the bolts are too rusted to remove and recommends a full replacement of the catalytic converter. Are there other options available?
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    steven s

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    Legal options? Probably not.

    beemerjim guest

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    catalytic

    I don't live in California. Not too worried about it. I've read about some aftermarket bolt on models. do they work?

    cwbiii guest

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    Sort of...

    I went through 2 different pairs of Cats that I ordered on line.The first was a "high flo"
    and was a rip off all the way... it never worked right, they didn't honor their guarantee and there was nothing i could do about it unless I wanted to go through the hassle of suing (I'm in MA and the culprit was in CA). I had to write it off to experience.
    The second one I purchased from a more reputable source but it still never quite worked right either. Even though the BMW installed one is quite a bit more expensive it
    will come with a real guarantee. And will work as it should rather than with error codes every so often. My recommendation is to get it installed by a BMW dealer.
    I had a 740i at the time.

    Chuck
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    MGarrison

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    Bolts too rusted to remove? Seriously? Seems to me some determined effort with a dremel (with cut-off or grinding attachments) or a drill or a air-powered cut-off wheel could get the bolt ends cut off - unless there is absolutely NO access. However, I could see how a shop could suggest it's too time-intensive and costly to the customer for such a task. But, if the cat is bad, they still have to get it off to replace it (don't they?), so I take it they're suggesting replacing whatever is junctioned to the rusting joint as well?

    cwbiii guest

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    Band Clamp...

    The cat bolts onto the exhaust header(s) up front and uses a really slick clamp in the back. If the bolts snap you just drive them out and insert a new pair. They are special bronze bolts and nuts so buy them from the dealer. There is a lot of other stuff you need to replace beside the cat... the exhaust donuts, 2 oxygen sensors for each cat, (the car has a pair of cats) I recommend replacing the bolts anyways, the clamp should be replaced, and any portion of the stainless exhaust that shows sign of perforation or damage.
    Possibly the hanger brackets and suspension rubbers. You have to drop the heat shield. You may have to drop the drive shaft as well... be very careful of the
    rear portion of that shaft... the constant velocity joint back there is a $900 part... if it leaks you will have to rebuild or replace it. I was quoted 2K to have the service techs replace my cats, I paid approx $750 each time I did it myself. You do the math and decide if it is really worth the attempt, especially if you are inexperienced in this sort of thing. I've been repairing my own vehicles for 40 years or so... and have quite a collection of tools and equipment. I actually like to wrench it so I don't mind.
    I'm extremely careful since I've had a number of wrenching disasters over the years that have cost me considerably more time and money to fix than they should have because of either inexperience or lack of patience... I've learned the hard way to be patient and not force anything.


    Chuck

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    Beware of aftermarket cats

    My wife's Z3 needed a new cat and rather than spend the $2K on a BMW cat I opted for a $900 aftermarket fix. When I mentioned this to my independent BMW shop I was told that was a big mistake - their experience was that aftermarket cats were short lived. They were right...within a year I was back spending the $2K. That was probably five years ago, no problem since.

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