Quote:
Originally Posted by Harbor_Handed
A 180 will slow the engine warming up to its ultimate temperature by allowing the coolant to start flowing sooner than a 190.
There's a misconception that a thermostat maintains a more or less constant engine temperature that is its stated degree rating, but I found out in my own researches that this is not true. The main function of the thermostat is to get the engine warmed up to the proper temperature on cold days by blocking the flow of coolant until the indicated temperature is reached. Thermostats only regulate the minimum temperature of the engine but do not maintain a maximum temperature. Engines run significantly hotter than the degree rating of the thermostat.
"The biggest misunderstanding about thermostats is that people believe they make the engine run cooler. They don't necessarily do that. The cooling system and load on the engine determines how hot the engine gets, the thermostat fully open will still be the mercy of the coolant system's ability to remove heat.....The thermostat can only determine when the cooling system is allowed to start cooling the engine. It sets a floor, not a ceiling on engine temperatures."
http://www.tuneruniversity.com/blog/...the-advantage/
This is an interesting thread on thermostats and what they do and don't do, and there's a VERY informative interview with a Stant/Gates thermostat engineer in this thread.
https://www.jalopyjournal.com/forum/...mation.511046/
The general consensus that I found was that a low-temp thermostat will not keep the the engine at a significantly cooler temperature, and if that's what you're trying to do you'd be better served by optimizing your radiator (its ability to remove heat from the coolant/water) and fans. |
Good links and I'll have to do more reading on this.
I will say in your second link someone mentioned what I think might apply to our trucks at least some of the time: theoretically its true, but functionally it can set the engines operating temperature if the cooling system has far more cooling capacity than the engines capacity to generate heat.
The cooling system on our Rangers is pretty ridiculous- the radiator is massive and the coolant capacity is high compared to the amount of heat a 2.3l 4 banger can generate.
That said, you could still be right. My truck's ECM unfortunately doesnt pipe out engine coolant temperature via OBD2- just Cylinder Head Temperature. I do notice depending on load of course a fluctuation in temperature. I will say however that the electric thermostat saw CHT regularly go up into the 270 approaching 280 range, where now the worst it will get is 260 if I'm in 3rd accelerating up a steep hill (before with the electric it was at its worst cruising steady). For the shift to a mechanical 195 thermostat to make such a difference compared to the 208/195 electric thermostat even under load conditions suggests that the thermostat does regulate engine temperature at least somewhat, right? Again though, it does fluctuate so certainly you have a point.
I have a question though: if the cooling system determines the operating temperature entirely and the thermostat only really controls the minimum temperature (or the rate at which the engine warms up from the minimum temperature to the operating temperature designated by the capacity of the cooling system), why are you using a 180 degree thermostat in the first place?
Given that an engine wears less once warmed up due to expansion, it would seem IF the thermostat doesnt set the operating temperature, all you'd be doing is increasing engine wear by prolonging the warm up period. Right?
Honest questions- I'm open to being wrong about any of this. I think part of my issue is that I learned on older cars where the cooling systems were just DAMN large compared to the engine's capacity to generate heat...
**LATE EDIT** I have another question: if the thermostat doesnt control operating temperature on our trucks but rather just the radiator's capacity to cool the coolant, why did Ford put an electric thermostat in the truck in the first place?