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Thermostat misinformation?

Discussion in 'The Hokey Ass Message Board' started by miller, Sep 10, 2010.

  1. Thermostats aren't there to prevent your car from over heating, so taking them out shouldn't cause over heating. They are there to keep your engine at a MINIMUM temperature. You'll see adverse affects if you take them out in really cold weather, not really hot weather.
  2. Hnstray
    Joined: Aug 23, 2009
    Posts: 9,510

    from Quincy, IL

    Obviously you didn't read previous posts.............:rolleyes:

  3. B Blue
    Joined: Jul 30, 2009
    Posts: 281

    B Blue

    Yes you could. Not necessarily, but you could. If you have a pump that is capable of sending water through the radiator tubes at a velocity greater than 10 ft/sec and the restriction of the thermostat holds the flow down to say, 9 ft/sec, removing the 'stat could cause overheating. At the same time, say you have a two row radiator who's tubes are flowing at 12 ft/sec and replace it with a three row. Velocity of flow through the tubes will drop to 8 ft/sec and you will have good cooling. Not because of the extra cooling capacity, but because of the slower flow.

    By the way, I did not pull the 10 ft/sec out of my ass. Engineers have been using that value when calculating water system flow capacity from day one. I had know that for years, but only recently found out why. Cavitation.

  4. Road Runner
    Joined: Feb 7, 2007
    Posts: 1,226

    Road Runner

    I think you can get bad thermostats regardless of brand or quality. Some right out the box, others fail after a short while or get worse, like you describe.
    Best insurance is to keep an eye on the temp gauge and shut the engine down, if it gets too high.

    I installed mine 5 years ago on my daily driver truck and it has lasted thus far.
    Inspired by the article, I checked it in hot water on the stove this morning, to see how far it opens and at what temperature. It started opening at 180 and I felt comfortable installing it again.

    Whatever brand thermostat that keeps the engine around 180, should be fine.
    I suspect in bad thermostat, that look functional from the outside, the wax inside the copper piece is not sealed properly any longer.
    Last edited: Sep 12, 2010
  5. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 4,257


    Should have split it into three parts. 3)Does the radiator have enough surface area to transfer the heat in the coolant to the air flowing through the fins around the tubes?

    All is for naught if the radiator doesn't have enough surface area. And believe it or not, the amount of coolant held in the "tanks" above and below the radiator core can make a difference in how well a radiator works.
  6. olds34dude
    Joined: Aug 8, 2010
    Posts: 62

    from florida

    seems like the block would hold alot less coolant than the radiator and theat would be cooled by the cooler radiator fluid as it flowed into it?

  7. Yes I read it, thanks for the condescension though, but my comment still stands, it is not the main design goal to prevent over heating, and taking them out on a hot day and not having an over heating problem supports my comment. The primary purpose is to keep operating temperature at a minimum set level. Obviously there are other factors involved, but for the most part, that is the general purpose.
  8. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,410

    Flat Ernie
    Tech Editor

    When you burn your finger after picking something up you just cut with a torch do you want to:

    a: cool if off by holding it under a slowly dripping faucet


    b: run as much cold water over it as fast as possible

    Flow is king.

    PS - Your engine wants the same thing to get rid of its 'burn' ;)
  9. Hnstray
    Joined: Aug 23, 2009
    Posts: 9,510

    from Quincy, IL

    You are welcome on the was a counterpoint to your arrogance. We have no disagreement that the thermostat is intended to insure a minimum operating temperature............but it most certainly also is intended to keep the engine in an operating temperture range, not to allow it to rise to whatever circumstances may cause. The prior lengthy post quoting from an engineer who designs these things clearly indicates that is one of the design considerations. He says that the thermostat is designed to open only partially at the design temp (say 180* for example) and, in effect, reserves further opening capacity to enable greater coolant flow to keep the engine from rising above that temp under greater load.

    Whether you read that and disregarded the engineers statements in preference to your own beliefs, or did'nt read it, as I supposed, makes no difference in the basis for the "condescension". Personally, it seems to me common sense dictates it works for both purposes and the engineers confirmation of that is good enough for me.

    lothiandon1940 and tb33anda3rd like this.
  10. 29nash
    Joined: Nov 6, 2008
    Posts: 4,544

    from colorado

    Again, I parrott Flat Ernie's logic; :D

    All of the posts that talk about the coolant moving through the system too fast, resulting in inadequate cooling are fabricated theory; based on no facts whatsoever.

    There are three basic rules to follow to attain effective temperature control in a motor.

    (1)no restriction to coolant flow in the system,
    (2) no restriction to air flow through the radiator,
    (3) adequate radiator frontal area,
    Assuming those three things the motor will not overheat with the thermostat installed, and, should the thermostat be removed it will most certainly run cooler.

    Given items 2) and 3), if a larger pump (item 1), were to be used to move the coolant faster the system would remove more heat from the coolant, resulting in the coolant temperature in the radiator and that being reintroduced to the water jacket being lowered.

    I'm goin' to play with one of my cars.
  11. stephnsons
    Joined: Aug 30, 2017
    Posts: 3


  12. Truck64
    Joined: Oct 18, 2015
    Posts: 2,332

    from Ioway

    Worse, Politicians pass legislation that affect everybody.
  13. upspirate
    Joined: Apr 15, 2012
    Posts: 1,642


    On a side note, if you don't use a thermostat made in USA , your temp gauge reads in Fahrenheit so it will have an incorrect reading from a foreign ,metric thermostat that controls temps to degrees Celsius !!! :eek::rolleyes::p:D Just kidding of course as this thread was getting a little "heated"
    Hnstray likes this.
  14. ems customer service
    Joined: Nov 15, 2006
    Posts: 2,495

    ems customer service

    A OBSCURE PIONT our new epa formulated gas with alcohol runs hotter than 100% pure gas and high altitude gas can go hotter again. running 210 with a 195 thermostat is ok, and stay away from the gm dex-cool it will plug the radiator after awhile
  15. TagMan
    Joined: Dec 12, 2002
    Posts: 5,629


    You guys do realize, don't you, that this is a 7-year-old thread that's been beat to death both here & in other threads? :D
    Blues4U, wraymen and Hnstray like this.
  16. Gman0046
    Joined: Jul 24, 2005
    Posts: 4,976


    The thread might be 7 years old but we still have HAMB posters that still don't have the faintest idea what the function of a T stat is. In another 7 years they will still be posting the same thermostat misinformation. Ya can't fix stupid.
    TagMan, Blues4U and Legends47 like this.
  17. Blues4U
    Joined: Oct 1, 2015
    Posts: 2,565

    from So Cal

    Haha! Man, the overheating threads in this forum just keep on giving.

    Re cavitation. Dude above insisted that excessive coolant velocity can cause cavitation (formation of bubbles in the coolant). Wrong. Cavitation in a liquid occurs as a result of pressure drop, as the pressure in a liquid drops below the vapor point gas bubbles will form in the liquid. It is not the velocity of the fluid that causes cavitation, though it may be the velocity of the fluid being pulled by the mechanical action of a pump impeller that may be a cause of the pressure drop. But it is a pressure drop that causes cavitation, not velocity, and this is localized at the inlet section of the pump, and the gas bubbles then implode on themselves as the coolant transfers from the low pressure side of the pump to the high pressure side, resulting in cavitation erosion of the impeller. But this alone is not the cause of overheating in a cooling system (a worn impeller could be a cause), and it's not because the coolant is moving too quickly through the system, that is bullshit. Sorry, but that's what it is.

    This topic has more misunderstanding and more misinformation get spread around than just about any other topic.
  18. Beanscoot
    Joined: May 14, 2008
    Posts: 517


    I borrowed a camper van from a friend who "fixed" his overheating problem by drilling so many holes in the thermostat it was more hole than metal. On our road trip back (in the summer) we were on a many mile descent through the mountains at night. It was cold out and since the engine was pretty well coasting the whole way, it got so cold we were freezing because the heater put out no heat. When I did have to step on the gas a bit, the vehicle was bucking and jerking because the engine was on full choke.

    The electric cooling fan on the vehicle wasn't working, thus the owner's "fix".
  19. stephnsons
    Joined: Aug 30, 2017
    Posts: 3


    Very informative thread.
  20. stephnsons
    Joined: Aug 30, 2017
    Posts: 3


    Very informative thread.
  21. Truck64
    Joined: Oct 18, 2015
    Posts: 2,332

    from Ioway

    It's worth repeating.
    Beanscoot likes this.

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