Recently took a trip to the lake and while driving on the highway, my thermostat was way into the red just under 260... on the way back ... same thing!?! Keeps overheating. I wired my electric fan to a switch, so in the city i do not have problems with it ovrheating. what could be causeing this? and what can i do to fix this... i need to be able to drive the jeep on the highway without any problems. Any advice, similar situations, or words will help .... thanks