Stranger-Than-Usual Start-up Sound

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by alanfreed, Nov 10, 2008.

  1. alanfreed

    alanfreed Junior Member

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    Hello from a new user of the site :)

    My 2007 Prius is just over a year old and closing in on 50,000 miles. I have a question you folks might be able to answer for me. Of course I'm accustomed to hearing the normal "buzzing" sounds when I start the car, but I think that I am noticing a difference in the way it has been sounding these past few weeks.

    Rather than being a smooth buzzing for the first few seconds of powering up, it has a sound like the buzz is vibrating off and on as well. I hope I'm explaining this well enough for someone to recognize what I mean... if I get desperate, maybe I'll have to try to record the sound or something.

    It just seems to me that it used to be a more consistent buzz at start-up, and now it sounds like whatever makes the buzzing noise may be vibrating against something at the same time... so I get a normal buzz with intermittent "vibrating buzzes" mixed in.

    If anyone has any insight, I'd enjoy knowing what might cause that, and if it would be worth a visit to the dealership. Thanks!
     
    #1 alanfreed, Nov 10, 2008
  2. firepa63

    firepa63 Former Prius Owner

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    The thermos coolant pump quite often gets noisier in colder weather. At least that's what I experienced with my 04.
     
    #2 firepa63, Nov 10, 2008
  3. alanfreed

    alanfreed Junior Member

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    I had hoped to attribute it to cooler weather, but we had temps in the 70s last week (I'm at the other end of PA), and I was hearing it during that warm period. And I didn't notice this at all last winter.


     
    #3 alanfreed, Nov 10, 2008
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Alan,

    There are two usual noise sources upon startup. One is the coolant heat recovery pump that runs upon startup and shutdown. The other is the brake pressure accumulator pump that runs intermittently and can be forced to run by repeatedly depressing the brake pedal.

    My guess is that you are hearing noise from the coolant heat recovery pump, and that the sound may be due to looseness in the hardware that secures the pump to the body of the car.

    If the sounds happens all the time so that it can be demonstrated to your dealer's service writer, then you may wish to register a complaint. However since your car has logged more than 36K miles the repair may be chargeable.

    It doesn't sound like the problem is more than a nuisance, I would not expect any driveability or reliability issues as long as you don't see any warning lights appear.
     
    #4 Patrick Wong, Nov 10, 2008
  5. alanfreed

    alanfreed Junior Member

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    Thanks for the info! I was never sure exactly what those initial noises were in the first place, until I found this site. Hopefully it's just slightly annoying instead of a symptom of a real problem.

    I haven't had a single problem with the car (knock on wood), and I've driven it through 44 states in the past year!
     
    #5 alanfreed, Nov 10, 2008
  6. galaxee

    galaxee mostly benevolent

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    #6 galaxee, Nov 12, 2008
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