2010 Toyota Prius overheating issue, Nothing works!

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Phantomwarlord, Jul 28, 2021.

  1. Phantomwarlord

    Phantomwarlord New Member

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    A little while ago my prius popped a P261B error code. I took it into the dealership, they said it was the electric water pump, and thermostat (they wanted $1400+ to fix it). I decided to do it myself and replaced both parts with no issue, I also replaced the coolant, and bled the system. However the car still randomly overheats. The weird thing is the car will be staying around 185F-198F most of the time no issue, then it will spike to an unholy 230F+, sometimes it lingers here and sometimes it immediately drops back down to normal temps. I've run out of ideas of what it could be. If anyone can help me that would be greatly appreciated, and thankyou in advance. Most of the time my temp warning light on the dash does not come on.
     
  2. rjparker

    rjparker Senior Member

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  3. PriusCamper

    PriusCamper Senior Member

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    Sounds like air in the system still... Keep at it... You'll get the air out eventually!
     
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  4. Phantomwarlord

    Phantomwarlord New Member

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    I Opened up the bleeder valve till just coolant came out.....Could i be missing a step?
     
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  5. Phantomwarlord

    Phantomwarlord New Member

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    Everytime i pull over when it has this issue, the fans are running full blast.
     
  6. PriusCamper

    PriusCamper Senior Member

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    Gen 2 is what I'm familiar with and Gen 3 might be different, but when I had an air bubble creating overheating I'd take off the actual radiator cap when engine was cold and top it off. Many others on here have done the same. Maybe try that routine a few times? Also a free OBD2 app like "OBD Doctor" will allow you to monitor engine temperature while driving so you can avoid damaging anything with overheating.
     
  7. Phantomwarlord

    Phantomwarlord New Member

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    I'll give that a try, i'll also play around with the bleeder valve some more. I do have a way to read my temp
     
  8. ChapmanF

    ChapmanF Senior Member

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    Gen 3 doesn't have a radiator cap. It is a degas-bottle system. The plastic bottle isn't just an overflow reservoir; it's a pressurized part of the system, and is where the burped air ends up during burping.
     
  9. Phantomwarlord

    Phantomwarlord New Member

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    There is also a bleeder valve on the 2010 model.
     
  10. ChapmanF

    ChapmanF Senior Member

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    Yes; it is used for the initial fill, where coolant is poured into the degas bottle to the B line prior to burping, and at about the same fill level, a bit will come out the bleed valve. Per the repair manual procedure, the bleed valve and the degas bottle are both closed then, and the engine is started and warmed up to deliver the remaining air back to the bottle, where the level drops from B to F.

    After 2011, the bleed valve was discontinued, and the rest of the system remains the same. I have not seen the 2012 fill instructions to find out exactly what they changed in the fill and burp procedure with that valve gone. But it only ever played a small role during initial fill and before burping the system.
     
  11. Mendel Leisk

    Mendel Leisk Sand Pounder

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    I honestly don't recall if I did this when refilling our 2010 Prius (with the vent open), but I do recall refilling a previous Civic, vent open, and while pouring I could feel a strong gush of air out of that vent, all the while I was pouring.
     
  12. ChapmanF

    ChapmanF Senior Member

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    What else would you expect?
     
  13. Phantomwarlord

    Phantomwarlord New Member

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    I burped it with the vent open till i saw coolant come out, i'll try it again the way you mention. If this is because i bled it wrong imma feel like a tard.
     
  14. ChapmanF

    ChapmanF Senior Member

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    There are posters here who regularly follow procedures of their own that are different from what's in the manual, and the earth does not open and swallow them up. Anything that gets the air out does the job.
     
  15. Phantomwarlord

    Phantomwarlord New Member

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    "fine, i'll do it myself"
     
  16. AmazingFacts

    AmazingFacts Junior Member

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    You may want to unbolt the coolant reservoir and raise it up a bit while bleeding. Also is the coolant in good shape? Maybe it's getting diluted and old?
     
  17. Nathan Barbary

    Nathan Barbary Junior Member

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    I just changed the coolant on my car.

    I have a 2010 so it still had the bleeder by the sensor on top. If you don't have the bleeder there you could always loosen the sensor while idling.

    The procedure I followed was similar to the nuts and bolts video but I did a couple extra steps.

    1. Refill the overflow tank till it stops draining down.
    2. Run vehicle for 15min on a level surface with overflow cap open. I used Dr prius to go into maintenance mode easier.
    3. Close the overflow and crack the bleeder valve by the sensor.
    4. Turn the heat on hi and fan to max. Let it idle for another 15min so that the coolant circulates thoroughly.
    5. Crack bleeder again.
    6. Exit maintenance mode and take the car for a 20min drive with the heat on hi and fans up.
    7. Top up the coolant whenever it gets low

    I couldn't get my rad fan to turn on from idling because it wouldn't get hot enough. I checked the fans by turning on the a.c. and they both turn on and I monitored coolant temp with the torque lite app and it would hover between 65 and 86c so i figured everything was fine.
     
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