Befuddled. I have a 2001 f250 crew 4x4. I replaced the radiator last year with a new one. Seems when I have the plow on or off, i fill the coolant tank with 50/50 mix to just under where it says max cold fill. Sometimes going down the road i can see the "spray" at night with my plow on, like its spraying out the front of the truck. There are no holes in the radiator as i have pulled it and checked it. After a few days the coolant is down to the bottom of the tank. I dont see any leaks and the exhaust runs clear when warm or hot. I have seen coolant by my battery next to the radiator cap, but not much.( possibly spilled when filling)Could a bad cap cause it to "cook off" to a point and then stop when pressure doesnt go as high?

 

The seal under the could be dry rotted, or not venting properly. But I would first check the hose from the radiator to water bottle, make sure properly connected and not leaking. Also check upper & lower radiator hoses. Check under hoses and low spots in engine compartment for evidence of where leak has been going.

 

Problem seems to be solved, i'll keep ya posted. The return clamp from radiator to tank (of course it's a stock quick clamp) was seaping, I replaced it with a real clamp. seems to be working.