1983 5.0 over heating

[renospyder]

Well my project car has been over heating, but not all of the time. It is all stock. It has 130k on it. I've changed all of the fluids before winter and didn't see anything unusual with the fluids. It's not leaking anywhere in the cooling system. Just once in a while, the engine hot light comes on. If I let it sit for a while and restart it and drive it, it doesn't over heat again. It's really strange. I flushed the entire system and noticed nothing unusual in the fluid. I've replace the t-stat, checked all of the hoses and the water pump is working just fine. It runs just fine. It has A/C, but it hasn't been on when it over heats, and I'm just driving it normally. The only common thing is that I'm at highway speeds 55-65 when it happens. Any suggestions?

TM

[fivepoint-0]

radiator is most likely the problem. calcium deposits are clogging the radiator, not passing enough coolant thru to cool off at freeway speeds. check around for a wide 2 core radiator for a t-bird or mustang. another tip: a dual electric fan set up from a 90's z-28 fits the ford radiator with very minor notching on the top corner for hose clearance. they pull a ton of air. use two 30 amp relays. I only use one fan for outside temps under 80 degrees.

[I Love To Fix Cars]

There is a three core rad available for that car. I put one in my 84 turbo coupe and it work fine.

[amosmoses]

fan clutch maybe?