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Thread: Hissing from muffler

  1. #1
    Join Date
    Jan 2005
    Location
    Williamsburg, VA
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    Default Hissing from muffler

    A few times recently after getting out of the car, I hear a hissing noise near the rear axle. I look underneath, and see steam hissing from what appears to be where the muffler meets the exhaust pipe. No drippage, just hissing steam.

    Shouldn't exhaust be vented out the exhaust pipe? I see exhaust venting normally when the car is running. What's causing exhaust to be pressurized?

    Thanks!

    Norman
    '89 535i, 225000 miles, family owned... Williamsburg, VA

  2. #2
    Join Date
    Feb 2006
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    Oldham, England
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    3,078

    Default

    Quote Originally Posted by ElNormo View Post
    A few times recently after getting out of the car, I hear a hissing noise near the rear axle. I look underneath, and see steam hissing from what appears to be where the muffler meets the exhaust pipe. No drippage, just hissing steam.

    Shouldn't exhaust be vented out the exhaust pipe? I see exhaust venting normally when the car is running. What's causing exhaust to be pressurized?

    Thanks!

    Norman
    Sounds like you have a hole in your exhaust doesnt it? Put a rag over where the steam is coming out and see if its quieter. If there's a hole, I'll bet it is just to the rear of the joint between the section that holds the back box and the mid section

  3. #3
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    Oh, sure, that's what I expected. Admittedly I don't know exactly what's going on inside the exhaust system, but why is it hissing out the muffler when nothing is coming out the exhaust pipe?
    '89 535i, 225000 miles, family owned... Williamsburg, VA

  4. #4
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    Nov 2006
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    Default

    Quote Originally Posted by ElNormo View Post
    Oh, sure, that's what I expected. Admittedly I don't know exactly what's going on inside the exhaust system, but why is it hissing out the muffler when nothing is coming out the exhaust pipe?
    Could it be residual backpressure? As in, your muffler has an internal blockage and is building/holding backpressure. I have seen a muffler packed with formerly 'dry' dog food which caused the car to run like crap and sound very quiet.

    It may be time to drop the muffler and see what there is to see.

    Brian

  5. #5
    Join Date
    Feb 2006
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    Oldham, England
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    Default

    Quote Originally Posted by ElNormo View Post
    Oh, sure, that's what I expected. Admittedly I don't know exactly what's going on inside the exhaust system, but why is it hissing out the muffler when nothing is coming out the exhaust pipe?
    The muffler has baffles in it. They make it harder for the exhaust gases to pass through. So if there is a hole in the pipe before the muffler the gases take the easier way out. Dont burn your hands, but if you put your palm close to where you think the hole is, you will feel it blowing. Maybe only a pin prick you can stop up with some exhaust putty-for now

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