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Engine and inverter coolant flush drain plug locations?

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by atikovi, Nov 8, 2023.

  1. atikovi

    atikovi Junior Member

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    Instead of just a drain and refill, I want to do a flush on both systems with distilled water four or five times before the final fill of pink coolant. i.e. drain, fill with water, drive 10 minutes until the thermostat opens, repete.

    I see there isn't a drain plug of the inverter but is there a block drain plug for the engine that would speed things up? Also, anyone know where you can get full strength pink like this stuff in the USA,

    [​IMG]
     
    #1 atikovi, Nov 8, 2023
  2. TMR-JWAP

    TMR-JWAP Senior Member

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    Not sure about that type, but I keep the Pentosin Pentofrost A4 on the shelf. It's the premixed version and runs about $25 for a gallon jug. It's essentially equivalent to the Toyota Super Long Life Coolant. Carried by many autoparts stores.
    I believe they also have concentrated versions available.
     
    #2 TMR-JWAP, Nov 8, 2023
  3. TMR-JWAP

    TMR-JWAP Senior Member

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    Not sure about that type, but I keep the Pentosin Pentofrost A4 on the shelf. It's the premixed version and runs about $25 for a gallon jug. It's essentially equivalent to the Toyota Super Long Life Coolant. Carried by many autoparts stores.
    I believe they also have concentrated versions available.
     
    #2 TMR-JWAP, Nov 8, 2023
  4. atikovi

    atikovi Junior Member

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    Nope just 50/50.
     
    #3 atikovi, Nov 8, 2023
  5. TMR-JWAP

    TMR-JWAP Senior Member

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    Pentosin A1 is offered as prediluted and as a concentrate. It is the equivalent of Toyota Long Life Coolant, iirc.

    Is there a reason you need to have the concentrate?
     
    #4 TMR-JWAP, Nov 8, 2023
  6. atikovi

    atikovi Junior Member

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    A1 is red, not the original pink I'm looking for and what the car came with.

    When you flush the coolant, there will still be some water left. Using 50/50 might dilute the freezing point to -10°F. Using full strength I can get back up to -35°F pretty easily.
     
    #5 atikovi, Nov 8, 2023
  7. ColoradoBoo

    ColoradoBoo Senior Member

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    In Gen 4, no need to flush....the two drain valves (on driver's side of radiator) drain both systems almost completely if you just let it drain for a long while (and open the radiator and caps on tanks.)

    Last year, the 2017 drain/fill took a gallon and a half of Toyota Super Long Life coolant. Specs says 6.6 Qts so sounds like I got all of it out.
     
    #6 ColoradoBoo, Nov 8, 2023
  8. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    I wouldn't bother, just drain and fill, with 50/50 Super Long Life Coolant, keeps it simple. Introducing water into the equation is a can of worms, best avoided.
    Judging from the Repair Manual, the inverter radiator is at the bottom on this gen, and drain is accomplished by opening a spigot on it.

    For both engine and inverter changes, see attachments.

    BTW, this is a 4th gen Prius? Your avatar doesn't show anything.
     

    Attached Files:

    #7 Mendel Leisk, Nov 8, 2023
  9. atikovi

    atikovi Junior Member

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    I can't imagine leaving old coolant behind is too good either.

    2020 Corolla. Same setup.
     
    #8 atikovi, Nov 8, 2023
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  10. ColoradoBoo

    ColoradoBoo Senior Member

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    Between 2017 and 2021, Toyota added a radiator cap to the Prius...not sure why...so engines may or may not have one in certain models.
     
    #9 ColoradoBoo, Nov 8, 2023
  11. atikovi

    atikovi Junior Member

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    I got the inverter drained. 29 ounces came out. Spec says 1.5 quarts or 48 ounces. Radiator next.
     
    #10 atikovi, Nov 8, 2023
  12. atikovi

    atikovi Junior Member

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    Radiator drained out a little more than 4 quarts out of a 5.7 quart capacity. At least the old coolant looks like new so I won't feel too bad leaving that much old coolant to mix with the new.
     
    #11 atikovi, Nov 8, 2023
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  13. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    This is what I got out, albeit of a gen 3:

    - engine coolant drain: 4.25 liters roughly
    - inverter coolant drain: 1.5 liter roughly

    With gen 3 there's a drain bolt on the bottom of transaxle, probably get most due to that, vs draining from the transaxle/inverter rad.
     
    #12 Mendel Leisk, Nov 8, 2023
  14. thomassster

    thomassster Member

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    There is quite a bit of travel from heat exchanger to other various areas where you will not be able to drain which an engine block drain probably won’t help. If you really want to go that route, there probably is some hose you can open up.
     
    #13 thomassster, Nov 8, 2023
  15. atikovi

    atikovi Junior Member

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    Inverter drained from lower valve,
    [​IMG]

    Then refill, activate inverter pump until all air comes out and pump is quiet, then top off,
    [​IMG]

    Radiator drained from upper valve,
    [​IMG]

    Then used vacuum filler to add coolant. Activated water pump for good measure then ran some errands and adjusted the level the next day,
    [​IMG]
     
    #14 atikovi, Nov 9, 2023
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