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Instructions for burping radiator

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Solohan50, Feb 3, 2024.

  1. Solohan50

    Solohan50 New Member

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    I'm hoping someone can assist me with this. I recently did the heat exchange bypass on my 2017 Prius One, but previously I'd lost a ton of coolant due to this issue and I'm needing to ensure that the radiator is filled completely and, presumably, burped to get all the air out. Does anyone have instructions on how to do this? I've looked around and haven't had much luck finding what I'm looking for. Any help you can give me would be greatly appreciated. Thanks!
     
    #1 Solohan50, Feb 3, 2024
  2. FuelMiser

    FuelMiser Senior Member

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    Which bypass method did you do, top or bottom? Not that it matters for your question, but curious.
     
    #2 FuelMiser, Feb 3, 2024
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    There's some tips in this:

     
    #3 Mendel Leisk, Feb 3, 2024
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  4. Solohan50

    Solohan50 New Member

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    I did what I assume is the bottom one. I installed the hose by the 2nd catalytic converter, as detailed in these instructions - 4th Gen DIY heat exchanger bypass solution | PriusChat

    Thanks for this! I do still need some guidance, if you're able to help. The part that I'm not sure how to approach is the Maintenance Mode. I assume Toyota doesn't put extraneous steps in their repair manual, but what does that do vs just running the car normally in terms of bleeding the coolant system? I can't find the thread, but I'm a bit gun-shy since I found a thread about a guy who put his car in Maintenance Mode and couldn't get it out of the mode, then had to fight with a dealer for a firmware upgrade to fix it.
     
    #4 Solohan50, Feb 3, 2024
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  5. Solohan50

    Solohan50 New Member

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    So I'm a bit confused by the instructions on how to bleed the coolant system. Step 3c seems to bleed the air out via burping the hoses and the air removal plug, but then you have step 3g that cryptically just says "bleed air from cooling system". Is that step supposed to be for systems without an air removal plug and they just didn't notate it or am I missing something?
     
    #5 Solohan50, Feb 8, 2024
  6. Solohan50

    Solohan50 New Member

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    Is there anyone who can shed some light on the above question?
     
    #6 Solohan50, Feb 19, 2024
  7. Solohan50

    Solohan50 New Member

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    Since nobody has chimed in, let me rephrase my question.

    I've followed the steps that were listed above. I removed the air release valve, burped the hoses, and reinstalled the air release valve. After that, how are you supposed to bleed further air from the system? After reinstalling the air release valve, the system is sealed and won't release further air. Is there a bleeder valve that I'm unaware of?
     
    #7 Solohan50, Feb 20, 2024
  8. bfroeba

    bfroeba Junior Member

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    To bleed out the air:
    Remove the one 10mm bolt which holds the reservoir and lift it up on the motor block.
    Set the climate control to "High" Temperature and the blower to level one.
    You have to start in maintainence mode and run the engine as long as the thermostat opened and let water circulate through the cooler for some time.
     
    #8 bfroeba, Apr 15, 2024
  9. Georgina Rudkus

    Georgina Rudkus Senior Member

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    Forget all the complicated methods using a radiator fill funnel, the maintenance mode or the complicated multi stage process.

    Drain the entire system and refill it with a vacuum refill tool like the UView or less expensive equivalent available at Harbor Freight,
     
    #9 Georgina Rudkus, Apr 15, 2024
  10. ChapmanF

    ChapmanF Senior Member

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    If gen 4 uses the same degas-bottle system used in the gen 3 liftbacks, it doesn't matter that the system is sealed. The extra headspace in the degas bottle is where the last of the remaining air ends up. It just gets circulated there by normal operation and trades places with some of the coolant.

    The gen 3 liftbacks even had an extra "air release valve" in the earliest builds, which Toyota later just deleted, and deleted the steps in the instructions where you would fuss with it, in favor of just letting the degas system do what it does.
     
    #10 ChapmanF, Apr 15, 2024
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