2005 CTS making loud rumbling noise

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Cadillac CTS First Generation Forum - 2003 - 2007 Discussion, 2005 CTS making loud rumbling noise in Cadillac CTS Coupe, Sport Sedan and Sport Wagon Forums; ...
  1. #1
    sandman64 is offline Cadillac Owners Member
    Join Date
    Jan 2014

    2005 CTS making loud rumbling noise

    I live in Northern Canada and we regularly get -30°C weather. Lately my car has been making a rumbling noise at low RPMs and now sometimes while idling as well. It wasn't as noticeable at first, but it definitely is now. It's LOUD (sounds like a diesel truck). When I accelerate it will kick in for a brief second as I pass whatever RPM seems to be causing it (which seems to switch around a lot). Does anyone know what might be causing this?

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  3. #2
    MoistCabbage's Avatar
    MoistCabbage is offline Cadillac Owners 10000+ Posts
    Automobile(s): 2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
    Join Date
    Sep 2010
    East Boston MA.
    Where's the noise coming from? Engine compartment? Exhaust?

  4. #3
    sandman64 is offline Cadillac Owners Member
    Join Date
    Jan 2014
    Thread Starter

    Re: 2005 CTS making loud rumbling noise

    The noise is coming out of the muffler. I should also note that the check engine light is NOT on.

  5. #4
    mattt0305's Avatar
    mattt0305 is offline Cadillac Owners Fanatic
    Automobile(s): 2007 6 speed manual tarnished platinum
    Join Date
    Feb 2011
    Southern Illinois

    Re: 2005 CTS making loud rumbling noise

    I had that happen on a grand Cherokee I used to own and turned out when I had some warranty work done which involved removing the exhaust, they dropped it and broke the catalytic converter internally. Sounded just like a diesel. It was pieces of the ceramic catalyst honeycomb getting tossed around at certain engine rpms. I thought it was the muffler but my cousin at the muffler shop instantly said it was the cat. No check engine light either.

  6. #5
    curtc's Avatar
    curtc is offline OCD - Obsessive Cadillac Disorder
    Automobile(s): White Diamond 06 STS V8 RWD 1SF F55 HUD/ACC NAV - 147k
    Join Date
    Jul 2005
    Oakdale, MN
    I would take a guess at a failed catalytic converter as well without actually hearing it first hand.
    Past Cadillac's

    2004 CTS 3.6L - 2011-2012
    2001 Seville Touring Sedan - 2006-2011
    1995 Seville Touring Sedan - 2005-2006

  7. #6
    93DevilleUSMC's Avatar
    93DevilleUSMC is offline Cadillac Owners Connoisseur
    Automobile(s): 1993 SedanDeville (RIP), 2006 CTS (current)
    Join Date
    Dec 2006

    Re: 2005 CTS making loud rumbling noise

    Check the catalytic converters and check for exhaust cracks. I just had this problem. The cause was a split in the pipe.

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