i have a 1972 F250 radiator losing water and running a little hot.
There is no visable signs that the water is leaking out is this a crack head or gasket problem. replaced the thermostat twice.

 

A Head Gasket problem would show up in the crankcase with a chocolate milk appearance.

Water Pump ?
Heater Core ?
Hose connections ?

White Coloured Exhaust ?

Also,I changed the spelling of a word so this thread can be found when searched for.

Losing = as in Losing Water

Loosing > No such word.


Oh yes, Welcome to FTE!

 

cracked heads or blown head gaskets aren't very common on these old engines, but you can check to see if there is severe bubbling in the radiator when the engine is running. This would be a sign of compression gasses being pushed into the coolant system. Also, check for radiator fluid coming out of the exhaust. Make sure that you don't accidentally mistake it for normal exhaust water condensation. How fast is the leak? Do you have to add a gallon every 50 miles or 5000 miles??

 

How much water loss are we talking? What does the water look like , ie. rusty, muddy? Take the oil filler cap off and see if there is any muddy, coffee (w/cream) colored junk down the filler neck. When oil and water mix, it's that muddy coffee with cream color. That would definitely tell you that there's a crack or bad gasket somewhere. Look in the radiator as well to see what that looks like. If all that looks fine, try carefully filling up your radiator without spilling water. Then run the engine until and see if you can find a drip on the ground to help you trace the leak. Could even be a freeze plug. Good luck.

 

As simple as this may sound, change out your radiator cap with a new one rated at the correct psi bleed off. I had this very same problem and my cap was letting the steam in the radiator bleed out, lowering the water level making the engine run hot.