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No More Whirring Sound After Shutdown?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by yibo829, Jan 18, 2012.

  1. yibo829

    yibo829 Junior Member

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    Hi everyone!

    I have a concern about not hearing the whirring sound after shutdown anymore. I know that the sound comes from a small electric-pump that pumps 3 liters of coolant into a thermal container (to keep it hot) every time I turn the hybrid system power OFF. When the power is turned back ON, the coolant is pump back into the engine.

    I've noticed that after I got an oil change and tire rotation at Pepboys the sound is no longer there after shutdown or power up. Then after a couple of days I took the car to the dealer to fix the tire rotation (because Pepboys didn't do a good job at rotating the tires, there was a woo woo woo sound while driving) and the dealer also did a multi-point check, but they didn't say anything was wrong with the car.

    I'm wondering if there is a problem with more no whirring sound after power up or shutdown? Did something happen to the pump? Is it no longer working? Then why didn't the techs at the dealer notice anything?

    Thank you for your help.
     
    #1 yibo829, Jan 18, 2012
  2. djasonw

    djasonw Active Member

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    It's possible the woo woo woo is shrouding the whir whir whir. Just a thought.
     
    #2 djasonw, Jan 20, 2012
  3. jpadc

    jpadc Type before I think too often

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    Welcome to PC yibo829:

    Sounds like you are hearing it sometimes and not others. I have noticed that sometimes the pump is delayed when the engine is hot (Over 192F), but it will run later, when the coolant actually cools down a little. Any chance this could be your issue? Do you have a way to monitor engine temp?
     
    #3 jpadc, Jan 20, 2012
    1 person likes this.
  4. qbee42

    qbee42 My other car is a boat

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    The transfer pump only runs if conditions are met. It won't run unless the engine coolant is significantly hotter than the coolant in the thermos.

    Tom
     
    #4 qbee42, Jan 20, 2012
    1 person likes this.
  5. yibo829

    yibo829 Junior Member

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    No, I don't have a way to monitor the engine temperature, but I did not know about the delay of the pump when the engine is over 192 F. The sound is back now, strangely. So I'm not really worried anymore. Thanks for the information though. :)
     
    #5 yibo829, Jan 20, 2012
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