I was having slight overheating problems with my car and found it to be a thermostat that was stuck slightly open. So it was running about 220 when it should have been running around 200. I was just curious and wanted to know what my truck was running (temp gauge is always right in the middle when it is warmed up). I hooked up my OBD2 computer to monitor engine coolant temperature. I drove it about 5-10 minutes and it got up in the 240+ range!! I thought that was way hot. When I got home I felt of the hose going from the engine to the radiator and it was very hot...could barely touch it. Then I grabbed the bottom hose that goes from the radiator to the thermostat/engine and it was ambient temperature. Not even slightly warm. I know the water pump is circulating at least some coolant because the heater works fine. If it wasn't circulating then no hot coolant would get put in the heater core. Does this sound like a bad thermostat? I am just amazed that the coolant gauge is still only half way at 245 degrees. Does this sound normal?

 

what engine? - i bet you have the 2.3 dohc

 

Yep