Does normal thermostat look like this?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by kobear18, May 11, 2021.

  1. kobear18

    kobear18 Junior Member

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    How can I tell if this thermostat is normal and working properly? I just took it out today and checked it out. I already ordered a new one but this old one looks very clean. It may not be the thermostat's problem. I thought the Bar's leak gummed it all up but NO. But there is no way to know just looking at it right? Maybe some of you guys have experiences? It looks like its in closed position now. I pressed hard to push it down and I guess that its in open position when I pressed it down? So what will push it down? I heard there is some wax expands to push it open but I don't see no wax. Let me show you photos below.

    I got another post about the P261B, temperature shot up after 177 F so I guess its because this is not opened around 180 F so temp shot up

    20210511_170257.jpg

    20210511_170304.jpg
     
    #1 kobear18, May 11, 2021
  2. AzusaPrius

    AzusaPrius Senior Member

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    #2 AzusaPrius, May 11, 2021
    Samuel Williams Jr likes this.
  3. Georgina Rudkus

    Georgina Rudkus Senior Member

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    Thermostat doesn't look good.

    I've owned the Scangauge II ever since I got my Prius v in 2012. With it, I continuously monitor 12v battery voltage, engine water temperature, inverter coolant temperature and HV battery temperature.

    Got it on sale for $120, Best money I ever spent.

     
    #3 Georgina Rudkus, May 11, 2021
  4. ChapmanF

    ChapmanF Senior Member

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    Well, you're not supposed to see the wax. It's inside that brass capsule.

    If you're ever looking at a thermostat and you can see the wax, that means it got overheated and the wax splurtched out, and now it's an ex-thermostat.

    If you don't see that, you can always dunk it in a pot of water on the stove with a candy thermometer and watch for the temperature when it opens.
     
    #4 ChapmanF, May 11, 2021
  5. kobear18

    kobear18 Junior Member

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    one more question? How can I check if my old water pump is working? Can I just plug it in without those 5 screws and turn on the car and see if impeller spin? But ya I took a lot of stuff out now, I guess I can NOT test it now. Thermostat and those 2 plugs are un-plugged and many hoses are un-plugged too. I will boil some water to test the thermostat later. If it still works, maybe I don't need a new one.
     
    #5 kobear18, May 11, 2021
  6. kobear18

    kobear18 Junior Member

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    I bought the "Dorman 902-5138 Engine Coolant Thermostat Housing" from Amazon. Is it good or not as good as the original?
     
    #6 kobear18, May 12, 2021
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