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2001 Prius Inverter Coolant Reservoir

Discussion in 'Generation 1 Prius Discussion' started by Lam57, Feb 19, 2023.

  1. Lam57

    Lam57 New Member

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    Hello everyone, I just got a 2001 Toyota Prius and when I go to check the coolant reservoir for the inverter, I saw big bubbles forming in the reservoir. Is this a cause for concern? or is it expected behavior? Forgive me if I’m wrong since I never owned a Hybrid before. I’m glad I have found this hidden gem on the internet. Thank you.

     
    #1 Lam57, Feb 19, 2023
  2. PriusCamper

    PriusCamper Senior Member

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    Is the coolant at the correct level? Can't tell from this camera angle... Looks like Gen1 Prius has a different reservoir than newer Prius. Maybe if you add more coolant it won't bubble like that. Regardless, not a concern unless you get warning lights for high temp coolant.
     
    #2 PriusCamper, Feb 19, 2023
  3. Lam57

    Lam57 New Member

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    It’s at the full line when the car is not running, but drops down to the middle, between the Full and Low line when it is running, then immediately rise back to full when the car is turned off. I will get a better picture tmr.
     
    #3 Lam57, Feb 19, 2023
  4. ChapmanF

    ChapmanF Senior Member

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    #4 ChapmanF, Feb 20, 2023
  5. PriusCamper

    PriusCamper Senior Member

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    I might not know Gen1 inverter reservoirs, but it seems clear to me that all the air is out and this air is because the input of coolant is higher than the coolant reservoir level and it's grabbing air as it enters.
     
    #5 PriusCamper, Feb 20, 2023
  6. ChapmanF

    ChapmanF Senior Member

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    Well, it shouldn't do that. :) Normally it wouldn't if the coolant is at the full line, as Lam57 says it is. So if that's what's happening, either Lam57 is mistaken about the full line, or the plumbing's been modified in some way. And after solving the problem, there's likely to be some air in the system, which it would be good to bleed out.
     
    #6 ChapmanF, Feb 20, 2023
    Lam57 and PriusCamper like this.
  7. Lam57

    Lam57 New Member

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    Hello, Chapman. I also saw a wave-like movement in my reservoir, that is accompanied with the bubbles shown above. I completely forgot to put this extra detail in. Sorry for any confusion.
     
    #7 Lam57, Feb 20, 2023
    Last edited: Feb 20, 2023
  8. Lam57

    Lam57 New Member

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    Still, I will definitely double check my readings again tomorrow morning, and report it here. Thank you all for the help. :)
     
    #8 Lam57, Feb 20, 2023
  9. Lam57

    Lam57 New Member

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    as promised, here are additional photos of the reservoir. This is the best angle i could do since there is a massive cable in the way.

     
    #9 Lam57, Feb 20, 2023
  10. ChapmanF

    ChapmanF Senior Member

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    Still seems to me the simplest explanation is there's air in there.

    It looks to be at the full line when off, because the total volume of air and coolant in the system comes to that level.

    Then when the pump runs, the reservoir level drops, because the pump is moving that coolant into the system where there was air, and the air gets pumped out as bubbles into the reservoir. If that drops the level enough to expose the intake port to air to suck in, then you've got a perpetual bubble machine for as long as the pump runs.

    And when you turn it off, the air ends up occupying high spots in the system and the coolant sloshes back and looks full in the reservoir.

    It's pretty much what you'd expect to see for a system with air in it.
     
    #10 ChapmanF, Feb 20, 2023
    Last edited: Feb 20, 2023
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  11. Lam57

    Lam57 New Member

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    Thank you very much for the detailed response. I suppose I should go straight to work then. What is the correct/accepted way to bleed the inverter loop on this particular Generation?
     
    #11 Lam57, Feb 20, 2023
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