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3 way coolant valve noise.

Discussion in 'Gen 2 Prius Technical Discussion' started by Tony714, Dec 6, 2020.

  1. Tony714

    Tony714 Member

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    This is a continuation of my previous question. No, I do not know how to link. If this is a bad move, moderators please tell me.

    2005, 230k miles. 3 way coolant valve popped up on code, P1121. Changed 3 way, drained coolant, refilled correctly. Air purged. Hoses installed correctly. Valve was aftermarket, not OEM.

    After install, valve SOMETIMES runs for like a full minute. What’s it mean? Am I in danger of blowing the engine? Danger of overheating? Should I get a new valve?
     
  2. PriusWave

    PriusWave New Member

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    Definitely get a new valve. Do not use aftermarket. Go to Toyota.
     
  3. dolj

    dolj Senior Member

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    It is generally not a good idea, why not just continue in the existing thread? It has everybody's input and a history of your problem.

    Previous thread: New noise after coolant fill
    My opinion is the aftermarket part is faulty or incompatible.
    No and no.
    Yes, I would get a new OEM valve. Aftermarket parts for this (the inverter coolant pump, and parts for the coolant heat recovery system) do not seem to be very reliable. I would recommend OEM for all of these. You could try returning the failed/incompatible part for a refund if you're feeling lucky.
     
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  4. Tony714

    Tony714 Member

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    Thanks all, I’ll try and figure out how to link next time I do this. Was just trying to get fresh eyes on the new post.

    And lesson learned, I thought by saving $30 I was coming out ahead.
     
  5. ChapmanF

    ChapmanF Senior Member

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    Can you say more about what you mean by the valve "runs"? Can you give a description of what you are hearing or noticing, what it sounds like, when it happens?
     
  6. Tony714

    Tony714 Member

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    The noise is definitely coming from the valve, and it is a whir and clicking noise. And being a little technologically deficient, I do not know how to attach a video so it can be heard.
     
  7. ChapmanF

    ChapmanF Senior Member

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    Repetitive kind of noise, like a washing machine agitating?
     
  8. Tony714

    Tony714 Member

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    I’d say yea
     
  9. ChapmanF

    ChapmanF Senior Member

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    Typical of when the valve's position sensor is flaky. Computer keeps wagging the valve back and forth trying to get the right position.

    Replacement with a Toyota valve would be the easy next thing to try. In the less likely event that one also wags, there might be other things to try, but test instruments would be involved. I'd just go with the valve first.
     
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  10. Jonnydwolf

    Jonnydwolf Junior Member

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    Replying to attach a video link to the YouTube I made so we can all hear what a flaky coolant control valve sounds like.

     
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  11. agrigento

    agrigento Junior Member

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    Hey there, I have been hearing the exact same type of noise, only that in my car it does it with a steady beat. This has been happening on and off for at least 10 months, but definitely more of often in the last 3-4 months--I now notice it every time I drive. At some point, it will stop for a several minutes, then it will start doing it again. No warning lights at all, and I've taken 200+ mile trips a couple of times. Would you say I just turn the music volume up, as my good old mechanic once told me? Or is this really a time bomb and I should replace the valve soon?
     
    #11 agrigento, May 19, 2023
    Last edited: May 19, 2023
  12. ChapmanF

    ChapmanF Senior Member

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    Different positions of that valve affect whether you have heat in the car or not, so if you're in Wisconsin you might think about replacing it before the cool weather comes.
     
  13. agrigento

    agrigento Junior Member

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    Thanks, ChapmanF! I'm actually in NWI these days, but the weather is not too different from South Central WI, so no heat in the car is definitely something I want to avoid. I was mostly worried about an overheated engine though. Is that a likely scenario too?
     
  14. ChapmanF

    ChapmanF Senior Member

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    As this diagram shows, as the valve switches between preheating and normal driving modes, coolant circulates through the engine in both of those modes, so engine overheating would be an unlikely result.

    But coolant does not circulate through the cabin heater in the engine preheat mode, so if the valve should get stuck that way, it could be chilly in the cabin.

    [​IMG]

    Now, what happens if the valve gets stuck in some intermediate position? I may not be prepared to absolutely rule in or out weirder outcomes. Maybe a closer look at the physical innards of the valve could show what might happen to flow as it moves between one intended position and another.
     
  15. agrigento

    agrigento Junior Member

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    Thanks a lot for the diagram and explanation! This is actually very helpful.
     
  16. rogerdpack

    rogerdpack Junior Member

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    My latest hypothesis on this is that the seesaw noise for a "new" (third party) valve might be OK if it goes away after awhile...maybe the computer's trying to retrain?
     
  17. ChapmanF

    ChapmanF Senior Member

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    Nope. The valve just has a simple position sensor (made from a potentiometer), and sometimes it goes flaky and sends a bad position signal. The computer then thinks the valve is in the wrong position, and moves it around trying to get the right position. Sometimes (when the sensor isn't too flaky yet), it can get to a spot where the position looks ok, and quiet down for a while. The flakier the sensor gets, the more it'll waggle around.