Fortunately I am not having any cooling problems with my vehicles. However, I have been involved in debates on another forum about the true function of the engine thermostat, and I thought I would pick the brains of some of the sages here.

The "other side" in these debates states that the sole function of the thermostat is to speed up the engine warmup process by remaining closed until the coolant approaches the proper operating temperature. They maintain that the thermostat opens wide at that time and remains open until engine shutdown and cooldown. If I understand their argument correctly, they are saying that the engine and cooling system are basically self-regulating as far as temperature, with the thermostat in the wide-open position.

I, on the other hand, don't see how this can happen. I maintain that once the engine warms to the proper operating temperature and the thermostat begins to open, it may only open partially, based on current cooling requirements, and that the thermostat must in fact cycle back and forth to some degree. I am not sure if it goes only from completely open to completely closed and back and forth. It seems more likely that it goes from "a little more open" to "a little more closed" and back and forth based on operating parameters and cooling system requirements at the moment. This would be based on a range of variables such as ambient temperature, engine load, condition of cooling system, etc. If you were pulling a heavy load up a long grade in high ambient temps, the thermostat might run wide open out of necessity. On the flip side, under light engine loads in cold ambient temps, the thermostat might spend most of its time nearly closed.

Well, I think I have stated my case. Any opinions are welcome. I would be particularly interested to see references to authoritative information.

 

Good question
I am in agreeance with you. The thermostat, should maintain a midrange while normally operating, keeping the temp of the coolant at the pre determined level. If i am not mistaken, one of the sighns that a thermostat is wide open, is that the engine runs cool, correct? So if the supposed thermostats opened and stayed open, the now computer run engines would experience problems and get Check engine lights, and the engines would run cold.
Pullin the thermostat out in the summertime in places it got hot helped older carburated engines run better, no overheat problems.
Also, cooling fans, electric thermostats in engines now a days help cool things/ keep them warm.
I agree with you, and stick by your story untill proven otherwise. Its good to see people thinking on how things work. BRAVO!!

 

if its too cold, it wont go into closed loop, you will get terrible gas mileage. i had a 160* stat in mine durning the summer and it did fine, but now that its cold out, it wont get up to temperature and my gas mileage went downhill fast. i put the 180 back in and its much better, runs better too.

 

Drop a new t-stat into a pot of water and monitor the temp. See what happens at different temps. You might be suprised.

 

I think you will find that it starts to open at a certain temperature and will be fully open at a certain temperature - and will be partially open at temps in between those 2, and varying its degree of openness. Its function is to try to maintain as close to a constant temp as it can.

 

The thermosat will open or close to keep the temp at it's designed level, 195, 180, 160, etc. The newer engines need the 195 to operate efficiently. I have a guage on mine and it takes about 7 or 8 minutes to get up to full temp and then it will bounce from 194 to 196 as I stop and go.