Thermostats: Opening and closing temp. Options

[RobbMeeX]

So I had been having a sneaking suspicion that my thermostat wasn't up to snuff. My car (95 Toyota Celica ST, 234k) never overheated, but temp fluctuated more than I would like (I don't want any fluctuation from city to interstate). So I researched and found the Stant Superstat ($10, made in America) and bought one for my car. I tested it on the stove. 180°f (82°c) open AND close. Tested good so I replaced it. Old one had no sign of anything funny UNTIL I put it on the stove. With my temp gun I measured opening temp at 170°f (76°c) and closing temp was not until 120°f (49°c)! That means when the car is warm its never getting to a good efficient temp. I have been getting 31mpg and have a 340 mile trip to take in a few hours. I hope to see an improvement in mpg based on the new temp. This particular tstat comes with a lifetime warranty so I can replace it in a few years if I sense funny business.

Stant# 45758

[Galcobar]

Your grammar makes it a bit difficult to understand your question -- or if you have one.

From what I can gather, the temperature guage would fluctuate when changing speed -- I'm going to guess that it was reading a lower temperature at higher speed. The thermostat you had in the car when you saw this fluctuation tested faulty on the stove, opening too early and closing too late. You then replaced the thermostat with a Stant thermostat.

The rated opening on the Toyota thermostat is 82C, with maximum opening of 8 mm at 95C. You can buy aftermarket thermostats which open at 76C, but I'd rather not. Seeing the temperature in your car drop as you drive faster indicates a thermostat stuck open, or as yours demonstrated, no longer calibrated to open at 82C.

Since you replaced a faulty thermostat with one which tested good, you should be done. Only caveat I would add is to be sure you installed the new thermostat with a new gasket, and with the jiggle valve correctly aligned.

[RobbMeeX]

Your grammar makes it a bit difficult to understand your question -- or if you have one.

nope, just observations

From what I can gather, the temperature guage would fluctuate when changing speed -- I'm going to guess that it was reading a lower temperature at higher speed. The thermostat you had in the car when you saw this fluctuation tested faulty on the stove, opening too early and closing too late. You then replaced the thermostat with a Stant thermostat.

Yup, bored with too much time on my hands


The rated opening on the Toyota thermostat is 82C, with maximum opening of 8 mm at 95C. You can buy aftermarket thermostats which open at 76C, but I'd rather not. Seeing the temperature in your car drop as you drive faster indicates a thermostat stuck open, or as yours demonstrated, no longer calibrated to open at 82C.

yup, sure is. I wouldn't go 76 because its too cold. Engines are more efficient at warmer temps.

Since you replaced a faulty thermostat with one which tested good, you should be done. Only caveat I would add is to be sure you installed the new thermostat with a new gasket, and with the jiggle valve correctly aligned.

And i'm done. Thanks for the tip on the gasket. (I'm a professional auto tech, but its a good suggestion for noobs). Also this Stant tstat had no jiggle valve.