I come from a family of seven kids, dad bought a used '66 289 Mustang for the oldest to drive. Each of us learned to drive in the Mustang, by the time it was my turn, #6 in line, the engine was so worn it wouldn't make heat. Dad cut off two of the four fan blades and blocked 90% of the radiator just to get enough heat to defrost the windshield. It was nothing to grab the fan blade and turn the engine over! I don't know the condition of your engine, but I do know a worn engine won't make heat!
My 250 makes all kinds of heat, I am betting the T-stat is partially stuck open.
Joe
