My current daily has this issue I have never seen before. The truck runs fine, heats up normally, has excellent heat, builds up normal pressure and the temp gauge is in the normal range. What I find questionable is after I shut it off and it cools down it sucks the upper radiator hose flat. Would this be a faulty radiator cap. It has the overflow container hooked to the radiator. As I write this I am thinking DUH... just change the cap. Anyone else run into this issue? It is a 95 F-250 with a 7.5L not that it should matter. Thanks in advance!