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2005 Prius thermostat issue.

Discussion in 'Newbie Forum' started by Prius Rising, Mar 20, 2019.

  1. Prius Rising

    Prius Rising Member

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    Hello: I have been stalking this forum for almost a year and finally signed up. I have a used 2005 Prius that I got for a song but had to put another ICE engine in as the previous one had thrown a rod right through the block. :eek: Everything seems to be fine other then the thermostat doesn't seem to open like it should. I did all the bleeding procedures after installing the engine the inverter coolant is swirling as it should. The radiator and all the hoses seem to be full.

    I took it out with the heat on full (heat works great) I came back home and the top hose on the right of the radiator is very warm but not really "hot" but the other hose that goes to the thermostat filler neck is cool to the touch.

    Like so many other things Prius I am wondering is this is just normal operating procedure for the car or is there a problem? (n) Any suggestions would be greatly appreciated.
     

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    #1 Prius Rising, Mar 20, 2019
  2. ChapmanF

    ChapmanF Senior Member

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    Have you got anything (ScanGauge? Smartphone with Torque app? ...) you can plug in to the diag port and watch the coolant temperature? Maybe you'll see it behaving normally. The thermostat isn't expected to open unless the coolant reaches the opening temperature (180-ish Fahrenheit, IIRC). It should get there in a highway drive of any length, but doesn't always when tooling through neighborhoods.

    Also, you had the heat on full. That'll suck about 5300 watts of heat right out of the coolant (about 7 horsepower) to blow on you in the cabin, before the thermostat even sees it or needs to send any to the radiator in front.
     
    #2 ChapmanF, Mar 20, 2019
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  3. Prius Rising

    Prius Rising Member

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    I took a 50 mile trip the other day some was highway and some 2 lane roads. No problems or lights coming on and the heat was on low that day. The Rad cooler fans have never kicked on that I know of but it's still winterish around here so maybe that'a a factor. I am on E bay ordering the OBD II Bluetooth adapter for Torgue pro now. It makes me a little nutty that they don't have a temp gauge in the car but that's the way she goes. I am not going to drive it again until I have something that can give me an accurate coolant temp.

    I hear that the heat is not exclusively controlled by the thermostat? (n)
     
    #3 Prius Rising, Mar 20, 2019
  4. ChapmanF

    ChapmanF Senior Member

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    Physics says the temperature is determined by the difference between the rate the engine makes heat and the rate at which the heat dissipates. The engine is both small and efficient, and sometimes not even running, so it doesn't make a whole lot of heat to begin with. A lot of the heat dissipates naturally into the environment, and more of it dissipates through the heater when you have that on.

    The thermostat is only there to open an extra passage to the radiator at the front of the car when/if it becomes necessary to dissipate even more heat to avoid overheating. Which isn't always needed, or needed much.

    I can keep a rubber sheet in front of my radiator from fall through spring. Drove 2,000 miles with it a week or so ago.
     
    #4 ChapmanF, Mar 20, 2019
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  5. Prius Rising

    Prius Rising Member

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    Yes, I am pretty mechanically inclined just never owned a hybrid. I heard there was some electronic device that helped heat the coolant when the car is cold so that you don't have to wait an hour for heat? It's been a long journey with this thing I don't want to blow it up again so I am being overly cautious. Here is what happened to the last engine. ;)
     

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    #5 Prius Rising, Mar 20, 2019
  6. ChapmanF

    ChapmanF Senior Member

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    There's an electric heat element that can kick in to help keep you comfortable while the coolant is warming up. It's really so small (700 watts, compared to 5300 available from the coolant once warmed up) that the effect is barely noticeable ... except for windshield defogging, makes a noticeable difference there.
     
    #6 ChapmanF, Mar 21, 2019
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  7. Prius Rising

    Prius Rising Member

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    I just got the torque app it looks like the coolant is measured in Celsius? Anyway to change to Fahrenheit or naw? I can do the conversion but would rather it's measured in "Merican" :)
     
    #7 Prius Rising, Mar 21, 2019
  8. ChapmanF

    ChapmanF Senior Member

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    It would be up to Torque to provide a feature like that; I would see if they describe it somewhere. In the worst case, you could learn how to write custom PID definitions for Torque and write your own version of the ECT PID with the arithmetic changed to come out in Fahrenheit.
     
    #8 ChapmanF, Mar 22, 2019
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  9. Skibob

    Skibob Senior Member

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    You could print a conversion chart out and use that. ;)
     
    #9 Skibob, Mar 22, 2019
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  10. TerryM

    TerryM Member

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    After opening the app, tap the gear on bottom left of screen. open settings, then units, make sure to uncheck Use Celsius. That should put all temp readings in F*
     
    #10 TerryM, Mar 23, 2019
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  11. Prius Rising

    Prius Rising Member

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    I checked all of that I think the problem corrects itself once I actually connect it to the car I am still waiting on my scanner to arrive on Monday. Thanks for the great tips though I am looking forward to actually being able to monitor my engine temps and battery blocks. o_O
     
    #11 Prius Rising, Mar 23, 2019
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