Thermostat temperatures

[ejay]

Going to be replacing my thermostat housing this weekend and might as well replace the thermostat as well. I think I used the 195 degree thermostat last install but I see 180 and 160 for sale as well. Any idea as to why someone would need one that opens at a lower temperature? Just curious.

 

[Jerry Bransford]

Go strictly for the 195 degree version which is what the PCM is programmed around. Going with a lower temperature thermostat would only screw things up and make your engine take longer to warm up on cold days. Modern engines run more efficiently at the temperatures they're designed to run at, plus you might not be able to pass a smog test with a lower temperature model.

Make sure too to avoid any thermostats that claim to be "fail safe". While that sounds good, fail safe thermostats tend to fail way too easily in the open position.

Stant is a great brand to go with, a Stant SuperStat is a very good model.

 

[chad]

Going to be replacing my thermostat housing this weekend and might as well replace the thermostat as well. I think I used the 195 degree thermostat last install but I see 180 and 160 for sale as well. Any idea as to why someone would need one that opens at a lower temperature? Just curious.

195 is what you need. The 180 or 160 could even throw a code. The motor needs to get to full operating temperature to run right.

 

[ejay]

Go strictly for the 195 degree version which is what the PCM is programmed around. Going with a lower temperature thermostat would only screw things up and make your engine take longer to warm up on cold days. Modern engines run more efficiently at the temperatures they're designed to run at, plus you might not be able to pass a smog test with a lower temperature model.

Make sure too to avoid any thermostats that claim to be "fail safe". While that sounds good, fail safe thermostats tend to fail way too easily in the open position.

Stant is a great brand to go with, a Stant SuperStat is a very good model.

Thanks. I figured. Any idea why the others are even available?

 

[Jerry Bransford]

Thanks. I figured. Any idea why the others are even available?

Mostly older models. My 57 Chevy used a 180 degree thermostat.

 

[Arizona Jeep]

The 195deg thermostat is the one you need to be able to pass smog inspection and to keep the pcm from throwing a DTC. The engineers had to operate the engine at high temperature in order to help the catalyst process and get the vehicle to pass emissions. If you were planning to operate "off road only" you could remove the catalytic converter, reprogram the pcm with HP Tuners and run 160deg thermostat and the engine would be happy. The pcm on most 4.0 liter jeep engines are set to go into closed loop operations after 176 seconds and -40deg F. Water boiles at 212deg, straight antifreeze boiles at 325deg and a 50/50 blend boiles at around 220deg. A trail jeep with the stock clutch fan and the stock 195deg thermostat reaches temperatures of 220deg on slow trails. This creates unnecessary pressures in the cooling system. Furthermore, it has been found through testing that most currently available thermostats do not open at the designated temperatures but rather 10 to 15 degrees hotter.