Strange sound after shutting engine off

Discussion in 'Gen II Prius Main Forum' started by 420benz, Mar 4, 2011.

  1. 420benz

    420benz New Member

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    Very hard to describe this sound but it is coming from under the hood and lasts for about 10 seconds.
     
  2. SWAT Native

    SWAT Native Junior Member

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    Is it a whirring or humming kind of sound? Mine does that, too. I figured it has something to do with the electric motor shutting down.
     
  3. 420benz

    420benz New Member

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    YES. It always had a humming sound,but it is much louder now and lasts longer.
     
  4. seilerts

    seilerts Battery Curmudgeon

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    Perhaps you are referring to the sound of the pump on the coolant heat storage tank? After you shut off the car, this pump fills the thermos-like tank with hot coolant so that the engine can warm up faster and have lower emissions on the next start.
     
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    You should hear a similar sound as you are starting up the Prius for the first time in the morning.
     
  6. Rae Vynn

    Rae Vynn Watch out, I have a degree in BS!

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    If you peruse the Owner's Manual, you will see several entries concerning various sounds that the Prius makes, when the engine is not running/Power is not "ON".

    All of these entries note that "this sound is perfectly normal"
     
  7. JimboPalmer

    JimboPalmer Nadir of Wrongness

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    I have never been "perfectly normal", what's that like?
     
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  8. seatown7

    seatown7 Northwest Prius Dork

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    I've heard its quite boring and tedious...;)
     
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  9. Rae Vynn

    Rae Vynn Watch out, I have a degree in BS!

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    "Normal" is a setting on a clothes dryer.

    For the rest of us, "Functional" suffices :thumb:
     
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  10. 420benz

    420benz New Member

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    Thanks guys. This is a great forum.
     
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  11. richard schumacher

    richard schumacher shortbus driver

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    It could be the sound of the coolant transfer pump failing. A failing one tends to get noisier in cold weather.
     
  12. 420benz

    420benz New Member

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    Where is it located and is it a DIY replacement?
     
  13. Patrick Wong

    Patrick Wong DIY Enthusiast

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    It is located near the coolant heat recovery system canister, in the front left wheel well in front of the tire. Replacement could be DIY if you consult techinfo.toyota.com or look up my post about how to replace engine coolant.

    However I wouldn't go to the trouble of replacing the pump just because it is noisy. If no DTC is logged by the engine ECU (which would cause the check engine light to appear), then no worries.
     
  14. Sam23

    Sam23 New Member

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    I have a 2007 Prius with a similar noise that seems to be getting louder/more obnoxious. Did the pump ultimately fail regarding the original post on this thread?
     
  15. PPENDOR

    PPENDOR New Member

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    Maybe not, I have a 06 prius. the Inverter Pump get relative gentle noise in summer and loud in winter. I tried to bleed the pump. Yes, few air seems like comes out but it doesn't help about the noise issue. Never mind, I just ignore it. I will change the coolant in next summer regards to the 100K mileage.
     
  16. CooCooCaChoo

    CooCooCaChoo Junior Member

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    Yeah theres a buzzing sound that comes from the front of the car, lasts bout 10 seconds max.
     
  17. bisco

    bisco cookie crumbler

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