Intermittently noisy coolant storage pump

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by dwill207, Mar 27, 2012.

  1. dwill207

    dwill207 Junior Member

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    I have an 05 Prius with pump issues. My coolant storage pump has been making an intermittent coarse squealing noise since I've owned the car. It seems to be worse in cooler weather. It only happens when turning the car off. Does anyone know if this pump only operates after shutting the car off? If that's the case, then I won't worry too much about it. If it's supposed to function when the car is on, then I may worry. Does the pump keep running until it's finished, or is it just a timed cycle? I'm concerned if there's air in the line, it may prevent the pump from completing it's job if it's on a timed cycle. Also, if I have to replace this pump, how would I go about bleeding all of the air out of the system?

    Thanks for any help...
     
    #1 dwill207, Mar 27, 2012
  2. dogfriend

    dogfriend Human - Animal Hybrid

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    #2 dogfriend, Mar 27, 2012
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    This is a known problem. The pump usually will run when the car is first turned on, and when it is turned off. The pump is controlled by the engine ECU and it is unclear whether the length of run is governed by coolant temp at the coolant heat recovery system canister or a timed cycle.

    I have posted on how to replace engine coolant and bleed air. This is a time-consuming process because of the CHRS canister. Basically I suggest that you need to run the CHRS pump manually in order to fill the canister, via shorting the appropriate CHRS relay socket terminals. You also need to run the engine at high RPM to fill the heater core loop and get air out of the coolant system.
     
    #3 Patrick Wong, Mar 27, 2012
  4. dwill207

    dwill207 Junior Member

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    Thanks for the info. I'm wondering, since the pump only makes that noise when the car is shut off and never when it's on... Can I assume it's ok to drive? My warranty has expired and can't afford to get the pump replaced now, especially since I'm going on a trip to Southern Cal in a little more than a week. I'm thinking since the pump only makes noise when the car is off, it should be ok.

    Thanks...
     
    #4 dwill207, Mar 27, 2012
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes, you can drive the car. Even if the pump fails, it will not cause any driveability issues but you can expect the check engine light to turn on since the emissions controls will be (slightly) impaired.

    I would not worry about replacing the pump unless it fails. Think of the noise as an undocumented "feature" of your Prius, instead of a "fault".
     
    #5 Patrick Wong, Mar 27, 2012
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  6. dwill207

    dwill207 Junior Member

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    That's good to know. A weight has been lifted. One less worry about my trip. Thanks again.
     
    #6 dwill207, Mar 28, 2012
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