Rattling catalytic converter on n*
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Northstar Engines and System Technical Discussion Discussion, Rattling catalytic converter on n* in Cadillac Engine Technical Discussion; There seems to be a rattle under my wife's 94 deVille N* - especially when the car is parked and ...
  1. #1
    Andrew M. Franklin is offline Cadillac Owners Member
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    Rattling catalytic converter on n*

    There seems to be a rattle under my wife's 94 deVille N* - especially when the car is parked and idling there is a general tinny rattle near cat. Is it possible the element is loose in the housing? Is this common? Is there a way to repair this? Thanks. Sincerely, Andy.

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  3. #2
    mcowden is offline Cadillac Owners Connoisseur
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    Re: Rattling catalytic converter on n*

    It might just be the heat shield rather than the internals of the converter. They can work loose or a support can rust away and they need to be fixed. That would be easy. If the internals of the cat are broken and rattling, the only repair is replacement. Any muffler shop should be able to tell you which one it is, as long as the rattling will happen when you take it in there. If it doesn't rattle while you're driving, my money's on a loose heat shield. I have the same problem and just haven't been motivated enough yet to crawl under there and fix it.
    Mike

  4. #3
    Jack Ammann's Avatar
    Jack Ammann is offline Cadillac Owners Member
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    Re: Rattling catalytic converter on n*

    Hi Andrew...My "cat" took a dump a few thousand miles back on my '94 ETC. I just got me a straight tube that fit with the appropriate flange, took the cat off and put the tube in....and wa la...I had more horse power according to my "Butt" dyno...LOL...and all that rattling was gone

  5. #4
    vision864's Avatar
    vision864 is offline Cadillac Owners Member
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    Re: Rattling catalytic converter on n*

    I had the same thing happen to my 93' turned out it had just caught a rock and busted the material up inside it, if you can straight pipe go for it, an aftermarket universal for mine cost 300 bucks

  6. #5
    mcowden is offline Cadillac Owners Connoisseur
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    Re: Rattling catalytic converter on n*

    You certainly can put a straight pipe in the place of the cat and maybe get a little more power out of it, but realize that the exhaust will smell like gas, it's illegal, and you'll never pass an emissions test. An OEM-style replacement is $162 approximately plus installation. I would still have a look at the heat shield before you do anything with the cat.
    Mike

  7. #6
    tco43 is offline Cadillac Owners Member
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    Smile Re: Rattling catalytic converter on n*

    It is rare, but it does happen that the inner element of the catalytic converter separates itself from the shell and then gives off this obnoxious rattle. You can stop the rattle. Drill a small hole in the bottom of the shell to put in a sheet metal screw that will pin the element in one place. Make sure the hole is small enough that the screw is a tight fit. Cut off the point of the screw to a blunt end so it will not penetrate the element. It might take more than one or two screws, but it will work.

  8. #7
    strabo40 is offline Cadillac Owners Member
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    Re: Rattling catalytic converter on n*

    I had the same problem with my '92 deVille. While the car sat still idling, there was a rattling noise that drove me crazy. I thought it was a loose exhaust pipe, but could not pin point it. I finally took it to a shop and found that the catalytic convertor was bad, so I had it replaced for around $290. They showed me the old convertor and you could shake it like a baby's rattle and make plenty of noise. The car does not rattle anymore, plus the car has better response and seems smoother.

  9. #8
    peteski is offline Cadillac Owners Enthusiast
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    Re: Rattling catalytic converter on n*

    I had this happen to my 93 Eldo. I drove it for about a year until the sound got so awful while I was at the traffic lights that I decided to do something about it. A nice Caddy making such an awful noise! No good!

    It also rattled when I gunned the engine.

    I took it to Mineke (sp?) last year and they agreed that the Cat was bad. I got it replaced. We looked at the old one and the catalist brick wasn't visibly broken but it was loose in the housing.

    No more rattles!


    Peteski

  10. #9
    rockytfox is offline Cadillac Owners Fanatic
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    Re: Rattling catalytic converter on n*

    Can a broken element in the catalytic convertor block air flow and create sluggish acceleration?

  11. #10
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: Rattling catalytic converter on n*

    Yes.

  12. #11
    mcowden is offline Cadillac Owners Connoisseur
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    Re: Rattling catalytic converter on n*

    Quote Originally Posted by rockytfox
    Can a broken element in the catalytic convertor block air flow and create sluggish acceleration?
    Ranger is right. It can absolutely kill your acceleration. Replace the cat.
    Mike

  13. #12
    rockytfox is offline Cadillac Owners Fanatic
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    Re: Rattling catalytic converter on n*

    I'm thinking about just using a straigh pipe for awhile. Does anybody know of a good replacement cat that wont go out in a year?

  14. #13
    mcowden is offline Cadillac Owners Connoisseur
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    Re: Rattling catalytic converter on n*

    Quote Originally Posted by rockytfox
    I'm thinking about just using a straigh pipe for awhile. Does anybody know of a good replacement cat that wont go out in a year?
    You can get a WALKER Part # 15815 direct-fit (not universal) catalytic converter for $140 at www.rockauto.com.
    Mike

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