I have a 1992 Dodge ram 250 extended cab long bed 4x2 with the 5.9 diesel in it with an automatic trans, every time I pull my 27 ft boat up a slight hill it wants to start to overheat. I got one of those hand held thermometers and it shows nothing over heating in the head area, block, radiator etc... all shows running normal. There is however a relay that gets very hot, if the temp gauge shows to hot it will shut the engine down for a minute, then it starts right up and slowly cools down until the next hill or continue of the same hill