I have a 1995 F250 with the 351 Windsor V8, recently i have been getting a higher temp reading on the engine temp gauge. I changed the oil, that didn't make any difference. My radiator and overflow won't transfer the fluid back and forth, it either just spills out of the overflow going over bumps, as well as the radiator itself will not send the fluid into the overflow when running. I checked the hose for obstructions and there was none, the fittings seemed to be air tight, but that may be a possibility. Hoping to hear your thoughts for further investigation on the problem.

 

Inspect/test/replace the radiator cap. Use a real gauge with numbers to verify the true engine coolant temperature. I have also used a cheap infrared heat gun pointed at the thermostat housing to check and verify the temperature matched what my mechanical gauge was displaying.