I bought a 1975 f250 about 2 years ago and discovered that it overheats when going 60 mph or above. In town, absolutely no problems. Had the engine rebuilt supposedly cleaning out the water passages, replacing the sending unit, thermostat, water pump, fan clutch, hoses and etc. Also pressure tested the radiator. Problem still occurs. Can anyone help? thx - jrs
I guess you replaced the radiator cap. Is it overheating on the temp gauge? Is it running lean. Is the timing correct? Usually at speed there is enough air flow to keep the engine cool, no need for a fan at that speed.
The overheating might be caused from a partially restricted radiator. If the radiator is restricted it loses it’s cooling capacity. And with that big 460 CID engine cruising down the road it creates a lot of heat.
Have the radiator checked for restrictions by pointing an infrared thermal gun at the cores. Those cores that are found to be cooler than the rest are the ones that are restricted.
Tester
Did replace the radiator cap with new, 13lb. Truck has not boiled over yet but the temperature guage almost (not quite) pegs. Next week I am going to add a new instrument cluster just to get more accurate reading on the temp. thx jrs
will do, thanks for the tip - jrs
Found the problem - Mechanic who rebuilt engine wanted to sell me a new radiator so he retarded the timing by 4 degrees - jrs