Explorer Running Cool

[lotic]

Is it bad on the engine if the engine runs cool? Have a 99 Ford Explorer and the temp guage needle just slighty rises past the C on cold mornings in which we have had lately. Low 30's. I commute about a hour to work in the morning and pretty much all the way is highway & the needle will not rise hardly above the C. I do notice that when i am in traffic in the morning the temp. gauge starts to rise, but once i start moving again it starts to drop back towards the C. Now when the temperature outside is in the 50's or higher the temp needle rises and stays at the temp icon in the middle of the gauge and does not move until of course the truck has been sitting for it to cool back down.
By the way, i still get very hot heat and my top radiator hose gets hot even though the temp gauge is slightly above the C. Does anyone else have these sort of problems in cold weather?

[srercrcr]

Do you get that hot heat relatively quickly? If not, it sounds like a thermostat stuck open.
How's your gas mileage? If the engine doesn't get up to a proper temperature, the computer forces it to run in closed loop....meaning, it thinks it's cold outside and therefore needs a very rich air/fuel mixture (like when carbed engines ran with the choke on). Staying in that mode would get you poor fuel mileage, and probably black exhaust coming out the tailpipe.

[lotic]

I get heat very quickly. I don't get any of the black smoke coming out of the tailpipe and my gas mileage is pretty good. Have not noticed any change in that.
Actually the needle is between the brackets that start after the C and ends before the H.
It stays on the low end where the bracket starts toward the C. In the older Explorer's their would be the imprint of "Normal" written in between those brackets. So maybe its ok. But i have no problems with heat at all and again i get heat rather quickly.

[B33p3r]

I can't tell you where "YOUR" temp needle should read. Mine rides just shy of halfway. I can tell you you shouldn't see those fluctuations. I'd still start with a thermostat check.

[truckdude239]

sounds like an thermostat gone bad stuck open