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How To: Change Inverter Coolant

Discussion in 'Knowledge Base Articles Discussion' started by usbseawolf2000, Sep 5, 2009.

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  1. usbseawolf2000

    usbseawolf2000 HSD PhD

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    I just uploaded a video to assist DIY inverter coolant change. I intended to include changing the pump but in a rush I forgot to do it. I hope this to be useful and save time for many of you.

    According to the maintenance manual, you need to change both engine coolant and inverter coolant at 100k miles. This video only covers the inverter coolant change.

    You will need the following:

    - 15/16" socket [$6]
    - Long wrench (preferably torque wrench to turn 29 ft/lb) [$26]
    - 2.2 US quart of Toyota Super Long Life Coolant (Dealer only sell in a gallon which is 3.7 US Qt. You'll need two gallons if you change both the engine and inverter coolant) [$20 per gallon]
    - 1 hour of your time

    Optional equipments:
    - Flexible Funnel [$2]

    [ame=http://www.youtube.com/watch?v=-yf6eCeV4M8]YouTube - 2006 Prius Inverter Coolant Change[/ame]
    9 people like this.
  2. hobbit

    hobbit Senior Member

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    You *did* bleed the little valve back into the reservoir, right?
    Otherwise you'll have air trapped in the transaxle.
    .
    _H*
    3 people like this.
  3. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Yes, I did. I left the valve opened and it started to overflow. I closed the valve and started the ignition. The inverter coolant started to pump and the reservoir level went down. I refilled it to full and opened the valve again, just to find more coolant leaking out (no air). That's how I knew I got all the air out.

    Thanks for pointing it out as I left out that detail in the video. I'll add annotations in the video.
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Nice idea to use that funnel that screws onto the coolant container. I had been using a regular funnel, but yours should be more convenient.
  5. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Thanks Patrick. I couldn't have done without your help.
  6. maxjlone

    maxjlone New Member

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    One of the most overlooked maintenance items on your car is the coolant system. Most people don't even think about it until they are on the side of the road with the hood up and steam pouring out of the radiator. This traffic nightmare can be avoided by some simple routine maintenance.
  7. andyprius

    andyprius Senior Member

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    Thanks for the video.btw. there are 4qts to a gal. you probably looked at the liter conversion.
  8. jreed

    jreed New Member

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    Thanks for making this video and posting it! I watched it and it helped me get the job done. I especially liked the way you captured the sound of air in the pump before bleeding.
    I attached a 2' length hose to the bleeder screw and fed the coolant from the hose back into the reservoir.
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  9. gsowash

    gsowash New Member

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    Would it be about the same procedure to change the inverter/converter coolant for a 2002 Prius?
  10. usbseawolf2000

    usbseawolf2000 HSD PhD

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    We need input from classic Prius owners (Patrick, Bob, anyone?)
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    It is "about" the same in concept. The reality is that it is more difficult to get air out of the system. The Classic inverter coolant system has two bleed valves.
  12. elendilmir

    elendilmir Junior Member

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    I've been meaning to ask: what is the reason for this? Do they both have to be bled during the process? Do they go to different loops?
  13. savrip

    savrip Junior Member

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    Great video. I'll be looking it up when I get near 100k. Doesn't hurt to keep myself informed.
  14. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I don't know why the Classic inverter loop is harder to bleed or why two bleed valves are involved; I just know that it is much harder based upon personal experience. Plan to spend two or three hours working on it, the first time you do this.

    I suggest that you 1) listen to the inverter coolant pump before you begin work, so that you can hear what it sounds like, 2) look at the fluid turbulence in the inverter coolant reservoir so you know what that looks like, and 3) measure the volume of the drained coolant, so that you know how much needs to be added.

    You need to work with both bleed valves, and cannot declare victory until you no longer hear air bubbles in the inverter coolant loop, you see turbulence in the inverter coolant reservoir which proves that fluid circulation exists, and you've added substantially the amount of fluid that was previously drained.

    After you've worked on the bleeding process for a while and don't seem to be making further progress, it might help to take the car for a short drive "around the block". The increased inverter heating from the drive seems to encourage some of the trapped air to purge out. However you don't want to drive long distances until proper coolant flow has been restored.
  15. bufffy21798

    bufffy21798 New Member

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    Awesome video, made my coolant change a piece of cake. Thanks!
  16. project_tl

    project_tl Junior Member

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    I did the inverter change, but I have been bleeding it for about 20 mins, but i cant seem to get it to go back to the normal sound. Its still making the weird whining noise. Any tips?
  17. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Do you have 2G or Classic?

    What is your bleeding process?
  18. project_tl

    project_tl Junior Member

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    2G,
    I am just opening the bleeding screw, and I attached a little rubber hose to the screw, and had it go back into the reservoir. Is there anything else i need to do?
  19. Patrick Wong

    Patrick Wong DIY Enthusiast

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    OK, that is the normal procedure. In fact you are doing better than me, as I don't bother to run a hose from the bleed screw into the reservoir. I just open the screw, watch fluid with bubbles come out, and close it when it looks like the fluid doesn't contain bubbles.

    The inverter normally makes a high-pitched whining sound around 5 kHz when the car is READY.

    The inverter coolant pump should sound like an aquarium pump when the car is IG-ON or READY. You should not hear air bubbling in the line, and you should see fluid turbulence in the reservoir. If you observe the turbulence and do not hear air bubbles then you can declare victory over this project.
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  20. project_tl

    project_tl Junior Member

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    I fixed it! :) I ended up attaching a rubber hose to the bleeder valve, and had it flow to a container that was ground level and kept pouring in coolant to the reservoir. Im going to assume that once the flow got going, and the momentum was able to get the air out.
    1 person likes this.
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