Whistling noise when car is shut off?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by parkp81, Aug 21, 2016.

  1. parkp81

    parkp81 Junior Member

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    I have a 2005 Prius with 122k miles, and have noticed for the past several months that the car is making a new type of noise that I did not notice before. It sort of sounds like a whistling noise.

    I did some searching and it looks like there are 2 pumps, a coolant heater pump and a coolant inverter pump. Not sure which one is possibly going bad? . I have not had any check engine lights.

    The previous owner had some service done at the dealer for the pumps. I have copied and pasted it from the service record I have for the car:

    74,441 MILES, 2/18/11
    SERVICE INCLUDES,CHANGE OIL & FILTER,AIR FILTER,WIPER INSERTS ONLY,INSPECT PROPE, AC FILTER SPECIAL FROM COUPON , INSTALL, REMOVE AND REPLACE ENGINE DRIVE BELT(S), REPLACED HYBRID WATER PUMP PER CAMPAIGN# A0N

    68,039 MILES, 6/23/10
    REPLACE COOLANT CIRCULATION PUMP FOR INVERTOR COOLING SYSTEM, N, THROTTLE PEDAL MODIFICATION

    Thanks
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    If the weather's been hot, might be gas cap venting excess air pressure.
     
  3. JC91006

    JC91006 Senior Member

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    It's probably the pump that runs for a few seconds to get coolant into the thermos. It only goes on when you turn the car on and off, doesn't do much else. My car has had this sound forever, doesn't damage anything
     
  4. parkp81

    parkp81 Junior Member

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  5. andrewclaus

    andrewclaus Active Member

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    If it makes the same noise on a cold start, it's the CHRS (coolant heat recovery system) pump. As noted, it's a common noise on a non-critical system.

    If you haven't done so lately, you might want to check the coolant level in the reservoir at the radiator. If that's low or empty, the noise could be a symptom of a bigger problem. A better test would be to look in the actual radiator cap itself, but that's harder and more dangerous to look at and probably not necessary if you're not comfortable doing it. If the reservoir is empty, then you need to look.
     
  6. parkp81

    parkp81 Junior Member

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    By cold start do you mean, start the car when it is cold and shut it off and listen for the same noise? Or while the car is running?

    The coolant was changed on the engine side and the inverter side, about 2k miles ago. Whenever I wash the car I check the oil and fluid levels.
     
  7. andrewclaus

    andrewclaus Active Member

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    Yes, start the car with a cold engine and you should hear that pump run for a few seconds, right before the engine kicks on. It won't run when the engine is hot, I believe.

    If the noise started after the coolant change, there may be some air in the system. Did a dealer change the coolant? It's tricky to get all the air out, and even some dealer mechanics don't get it right. It's the wrong season for it, but do you know if the cabin heat works okay? Any liquid noises in the dash?
     
  8. parkp81

    parkp81 Junior Member

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    Ok, I don't hear it when the engine is started cold.

    Im a DIY type of person and I try to do as much of the work myself. I changed the coolant, and followed the DIY tutorial I found on here where you use the paper clip method (run the inverter pump). I checked several times to make sure there were no more air bubbles coming out of the bleeder valve with a clear hose attached to the nipple, before I called it job complete. The heater works fine, and I do not hear any liquid noises in the dash area.
     
  9. andrewclaus

    andrewclaus Active Member

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    Back to the noise mentioned in the first post. When do you hear that noise?
     
  10. parkp81

    parkp81 Junior Member

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    I hear it after the car has been shut off. I will try to see if I can get a audio clip of it tomorrow after I drive the car
     
  11. JC91006

    JC91006 Senior Member

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    It's the CHRS thermos pump, I get it whenever I shut down my 2006. It's like a tea kettle.

    Since this pump works for only 10 seconds at a time, I didn't bother changing it. Gives the car character
     
  12. andrewclaus

    andrewclaus Active Member

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    With that timing, I agree it is the CHRS pump, no need for audio. "They all do that."

    You could try cycling the pump a couple more times for 30 seconds each.

    I'm just surprised you don't hear it on a cold start. It should make roughly the same noise then.
     
  13. DD1

    DD1 Junior Member

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    -----
    I am having a similar issue after shutting off the car. I attach the video of the noise. Do you think the tea kettle noise comes from the CHRS pump? It sounds as if it is coming from the area of the engine water pump/front right wheel. It does not come from the radiator cap as far as I can tell.
    https://share.icloud.com/photos/03DFg-V2DK5kaH6kn7tifEzBQ
     
  14. JC91006

    JC91006 Senior Member

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    I couldn't access your video, but if you hear the sound after the car is shut off, it can only be the CHRS pump. Nothing else is on.
     
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