1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Coolant level

Discussion in 'Gen 4 Prius Technical Discussion' started by Knarff, Sep 29, 2024.

  1. Knarff

    Knarff New Member

    Joined:
    Sep 28, 2024
    1
    1
    0
    Location:
    Norcal
    Vehicle:
    2016 Prius
    Model:
    Three
    2016 with 61k miles… and coolant in bigger reservoir on left side of engine bay sits at “low.” Should i top off? Is concerning?
     
    bisco likes this.
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    109,708
    49,854
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    check the o/m. see if that is appropriate when the engine is hot or cold.
    you do need to be concerned about a potential coolant leak in the exhaust heat exchanger, so i would top it up if necessary per the manual, and keep a close eye on it, like every day.
    coolant leaks can lead to head gasket failure, quite common on the early gen 4.
    there is a tsb for the dealer if you find the coolant level dropping.
     
  3. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    56,262
    39,031
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    4th gen's with dropping coolant is often that exhaust heat recover system. Compounding that, dealerships may diagnose as head gasket failure (though protracted neglect of the coolant level may lead to that), and even if they find it to be the exhaust heat recovery system leaking, they may try to bill you, instead of Toyota. This could either be incompetence, or intentional, since the labour rates they can charge corporate Toyota are less than their retail customers. Best track down that TSB, bring it with you.
     
  4. BiomedO1

    BiomedO1 Senior Member

    Joined:
    Mar 27, 2021
    1,689
    869
    0
    Location:
    SacTown, Ca
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    Welcome Knarff;
    I would stop by a grocery store and buy a gallon of distilled water. When the engine is hot, top-off to max line. Check it every day or every other day for the next few weeks. The levels will vary a bit but it shouldn't go low again; if it does - it needs to be checked out. You can destroy the engine if it runs out of coolant.
    As @Mendel Leisk stated; there's a TSB on this issue.

    Hope this helps....
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    56,262
    39,031
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Or stop by dealership and buy a gallon of Toyota Super Long Life Coolant (pre-mixed).
     
  6. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    24,720
    16,085
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Or just top off with the specified Toyota coolant. In the US, anyway, they don't seem to sell that except in 50/50 premix, which means if you have topped off with plain water, it's hard to get back to the intended concentration.
     
    Doug McC likes this.
  7. m8547

    m8547 Senior Member

    Joined:
    Aug 8, 2018
    941
    617
    0
    Location:
    Colorado
    Vehicle:
    2018 Prius Prime
    Model:
    Prime Plus
    There should be an app or something for sharing partial bottles of coolant. I just topped up our Subaru, and I just changed the coolant in one of the Toyotas, so I have an open bottle of each type. If anyone's near Boulder, CO I'm happy to share.

    I'd suggest aiming for halfway between low and full so it doesn't overflow when it warms up.

    I noticed the same thing in my Prime around 60k miles. Both reservoirs were at Low when the car is cold. I topped them off since I have the coolant anyway.
     
  8. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    24,720
    16,085
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Pretty sure 2016 is still a degas-bottle system like gen 3. Plenty of headspace in the bottle above the FULL line, and that is the target level after filling and burping.

    The more pressing question is, did the old coolant go somewhere, and, if so, where?
     
  9. sclevine

    sclevine Active Member

    Joined:
    Dec 23, 2016
    119
    136
    2
    Location:
    New York, NY
    Vehicle:
    2024 Prius
    Model:
    XLE
    Search this site for heat exchanger - you'll see plenty of threads on this issue.