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Weird rotating noise near driver area

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by lastradakiwi, Sep 25, 2024 at 6:03 AM.

  1. lastradakiwi

    lastradakiwi New Member

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    I recently bought a 2009 Prius with 86k miles. It drives great, and I did get it inspected before purchasing. The inspector said that the car is in great mechanical shape.

    I started hearing this weird sound coming from the front of the car in front of the driver area, and I think it comes from under the hood. It sounds like something rotating or wipers blades wiping really fast. I attached the sound, but you may need to put on earphones to hear it well.


    The sound isn't audible all the time, but it gets annoying after a while. I think I tend to hear it when I first start the car and at stop lights. It isn't too loud and it can blend into the background unless you really listen for it. Other than that, the car drives beautifully without issues. Does anyone know what is this sound?
     
  2. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Description is about right for a failing brake booster.
     
  3. lastradakiwi

    lastradakiwi New Member

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    I don't hear anything when applying the brakes. They are actually really smooth
     
  4. saneesh8

    saneesh8 Junior Member

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    I have the same 2009 model, but with 148k. Sound of the failing brake actuator from my car - - YouTube

    Replaced it with new one from Toyota, new one also makes this noise but rarely when it needs to build up pressure. Old one was every few seconds.

    Yours video, audio is very weak and kind of sounds like failing hvac door actuator. Put it into max heat and see if the noise disappears.
     
  5. lastradakiwi

    lastradakiwi New Member

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  6. bisco

    bisco cookie crumbler

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    if i'm hearing the sound right, i would guess hvac vent door. but the person in the thread you linked is sure it is the three way valve, so they are probably right.
     
    #6 bisco, Sep 25, 2024 at 1:47 PM
    Last edited: Sep 25, 2024 at 1:55 PM
  7. pasadena_commut

    pasadena_commut Senior Member

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    So it makes that noise when the car is stopped, right? That rules out all the parts which only rotate when the car is in motion.

    Does it make that noise when the ICE is off? If so I would open the hood and listen carefully to determine roughly where in the engine compartment it is coming from. If it makes that noise only when the ICE is on it might be hard to pin it down since the motor itself is moderately loud when it is running. A mechanic's stethoscope would be helpful.

    It is probably the 3 way valve which can "hunt" for a position when it starts to fail. Either that, but less likely from the sound, a failing inverter pump. Those are both parts that fail at 60k mile intervals (or something like that). You can replace them both yourself, but be aware space is tight around the inverter pump and stupid tight around the 3 way valve. Only use OEM parts for these from a known Toyota source. Don't buy one on Amazon or Ebay because even if it claims to be OEM it is likely to be a fake. Non OEM inverter pumps are notorious for early failures.
     
  8. lastradakiwi

    lastradakiwi New Member

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    It makes that noise when the car is stopped, such as when the car starts for the first few seconds before the gas engine kicks in. It also makes the noise when I'm at stop lights. Do you have recommendations on where to buy these parts?
     
  9. bisco

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    dealer only, too many counterfeiters out there
     
  10. lastradakiwi

    lastradakiwi New Member

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    I placed my hands (with gloves on) on the inverter pump this morning and did not feel vibrations matching the rhythm of the noise, so I don't think there's a failure with the inverter pump, but I could be wrong. Here's a video with a better recording of the noise under the hood.

     
  11. bisco

    bisco cookie crumbler

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    much easier to hear, but doesn't sound like the one in your link
     
  12. lastradakiwi

    lastradakiwi New Member

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  13. pasadena_commut

    pasadena_commut Senior Member

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    Much better that it be the 3 way control valve than the ABS system.
     
  14. saneesh8

    saneesh8 Junior Member

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    Yes.. way easier and cheaper to replace
     
  15. lastradakiwi

    lastradakiwi New Member

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    Thanks! I'll try replacing it and update you guys after. It'll probably take about a month or two for the part to arrive.
     
  16. bisco

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    the dealer doesn't have one?
     
  17. lastradakiwi

    lastradakiwi New Member

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    I'm ordering it online. I also have to order all the tools needed for the job, which I will reuse later for oil changes and related things
     
  18. bisco

    bisco cookie crumbler

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    good luck, the market has been flooded withlow quality chinese counterfeits
     
  19. pasadena_commut

    pasadena_commut Senior Member

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    ONLY from an actual Toyota dealer's web site. Not from Amazon. Not from Ebay. Not from some random internet site.

    Install a low quality part and you will be doing this job again soon. The 3 way valve is a PITA to get out and in, if I never have to do another that would be fine with me.