I recently went on a long road trip. During that time my engine temp peaked at about 240 w/ no A/C. (norm being around 190-200) Red line is 260. The first thing I changed was the thermostat. Didn't change a thing. I am hesitant to change my water pump because (1) it looks like it would be difficult and (2), I am not losing any water. The pressure in my upper and lower hoses seem to be sufficient. The strange thing is that the faster I go, the hotter is gets. if I go over 70mph, the truck would red line for sure. (Common sense would say the faster I go- more air in the radiator- the cooler the engine.) Once I back down to around 40mph, the truck cools to about 210 rather quickly. At a loss for what might be the problem. Any help out there?