>any coolant you put in the  expansion tank always either drips on the ground, runs to the reservoir filling it all the way to the top, or disappears?  I.E. my expansion tank is always empty.  

It sounds like you have a leak in you expansion tank?  This however would be a "catastrophic" problem as there is no way coolant would circulate in the system if the expansion tanks was always empty... Are you sure your calling them by the right name, the expansion tank is the one NOT behind the license plate...  

If backwards, then it sounds like you have a like in your reservoir (the one behind the license plate).  While this wouldn't cause and immediate problem, it's work sorting out.