overheating F250

I have a 1991 F250 5.8 manual ...drove it home no problem , but just a few hours later i started it to warm up, and when i got in ,my temp was way above normal. i kicked on the heater but was shocked to find no heat comming from the vents ...after futher inspection i found no apperant leaks ,other than the overflow at the top of the radiator, the thermostat is in workin order , and there are no abnormal noises. i checked radiator hoses top and bottom , they are in good shape. top hose is heating up while running ..bottom hose holds its shape. I checked the fan , and it also is working fine , i have not yet checked the water pump , but with this sudden loss of heat and high temp, I do not think this is the problem. If anyone has a suggestion , or has had a similar problem , im all ears.

Those are the classic symptoms of a blown headgasket. No heat, but overheating with the upper radiator hose hot.

Allow it to cool FULLY, remove the radiator, use all due caution, start engine and allow to idle. Ther will always be some small (1/8" diameter) bubbles, but larger ones, up to 1" diameter, indicate a blown headgasket or cracked head.

Sorry. I hope it's something else.

Also, headgaskets ALWAYS start leaking on cool down, they don't start when overheated, that's a result.

Thanks for the input modmech ... another inspection (this time more thorough) and 3 gal of mixed coolant later revealed my culprit.. a blown heater hose (inlet)...after replacement and a pressure check, which held fine , the beast is running at a normal temp, my heat is back and im relieved :) I took it on a 40 mile tour of the city and am pleased to report no overheating.