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Strange Noise @ Low Speeds

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by erinmnix, Jan 3, 2009.

  1. erinmnix

    erinmnix New Member

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    I've been hearing a strange "winding" type noise coming from under the car when I'm driving at low speeds (either just starting to move or close to stopping). My husband also said he's heard the same noise when the car is off completely - which is very strange. I don't know how to describe it really other than it sounds like a winding type noise, or perhaps a grinding noise without the destructiveness one would normally associate with "grinding." Anyone have any thoughts? I just got the car 2 days ago, so I hope there's nothing serious.

    Thanks in advance for any hints.
     
    #1 erinmnix, Jan 3, 2009
  2. efusco

    efusco Moderator Emeritus
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    If it's just at low speeds you may be hearing the whine of the inverter and/or MG2 as it propels the car without the ICE.

    There are a number of unique sounds to get used to with your Prius, but it's rare that it makes a sound it's not supposed to.
     
    #2 efusco, Jan 3, 2009
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Erin,

    One unusual sound is made by the brake pressure accumulator pump. You can force this pump to run by pumping the brake pedal repeatedly.

    Another unusual sound is made upon startup and shutdown by the coolant heat recovery pump. That pump moves hot engine coolant to/from the engine from/to the coolant heat recovery canister and is part of an unusual emissions controls system.

    Finally, five hours after shutdown, if you are near the car you may hear a pump runs that tests the fuel tank to verify its integrity.
     
    #3 Patrick Wong, Jan 3, 2009
  4. erinmnix

    erinmnix New Member

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    Thanks to you both! It makes me feel better to hear that the Prius generally has its own set of noises that I should get used to - so I can not worry about every noise I'm not familiar with. I don't know enough about the mechanics of cars - that's my husband's department - but I'm not sure if the brake pressure pump mentioned below could be the problem, because it does it when I'm either accelerating or braking and also when the car is off completely...perhaps it could still be that, just not sure. Seems like it would need to be something completely independent of acceleration or braking for it to happen in either situation - though I do hear it more often during acceleration.

    Thanks for the thoughts though - certainly makes me feel better.
     
    #4 erinmnix, Jan 3, 2009
  5. qbee42

    qbee42 My other car is a boat

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    Is it sort of a ratcheting type of sound coming from the driver's footwell area? The brake accumulator pump makes a grinding, ratcheting, buzzing sort of sound which lasts for about three seconds at a time. It can occur at any time, with or without the car moving, but is heard most often after using the brakes.

    Tom
     
    #5 qbee42, Jan 4, 2009
  6. maseace

    maseace Prius enthusiast

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    Maybe we should record and make a sound byte archive of all the Prius sounds that don't happen on regular cars. :)
     
    #6 maseace, Jan 4, 2009
  7. erinmnix

    erinmnix New Member

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    qbee - it is a ratcheting type sound and it is coming from the driver's footwell area - so perhaps it is the brake accumulator pump. That makes me feel a lot better because this noise started almost immediately after I drove the car off the lot and I was prepared to be pretty angry if there was actually something wrong with the car. Thanks for the help!
     
    #7 erinmnix, Jan 5, 2009
  8. qbee42

    qbee42 My other car is a boat

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    You are welcome. It's a common question. If you really pay attention to it, you will hear that sound about every third time you step on the brake. It won't be exactly every third time, but on the average about that. Sometimes it happens as soon as you power up. It's all a matter of the pressure in the brake system.

    Tom
     
    #8 qbee42, Jan 5, 2009
  9. richard schumacher

    richard schumacher shortbus driver

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    Just to be thorough: have you had any accidents in the car, or driven over or hit any objects while driving?

    You might be amazed by how often people ask questions like yours without giving such relevant information.
     
    #9 richard schumacher, Jan 6, 2009
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