The temp guage in my 2000 Chevy Blazer LS is not rising about 165 or 170 degrees. But i notice a little bit of steam coming from under the hood when its been driven for 30 miles or so. In my experience, this has always meant the thermostat ia stuck closed. Not allowing water into the engine. So the water thats in the engine keeping it cool is slowly evaporating. But the temp guage getting to 165 or 170 has me stumped. One would assume that the engine would be extremely hot and overheating if the thermo was stuck closed. So maybe its stuck open??
Im changing the thermo in just a little bit to see if that will help, or fix the issue. But i ak always looking for swcons opinions....
anyone??

 

I would also guess it's stuck open, unless the coolant level is so low that it won't register.