When I start moving my 92 f150 I hear what sounds like draining water behind the dash near the glove box. What is this and how can I fix it.

 

Hello, that would probably be your heater core. If you're hearing water, it may be air bound. Check your coolant level, and go from there. Peace, Dave.

 

^^^^yep

 

More than simply checking your coolant level, check it multiple times. If it is low then the heater core may very well have gotten an air bubble in it. If that happened and you replace the coolant once, you may have to top it off again after it pushes the existing air bubble out. Also, this air bubble developed from somewhere. I'd do a thorough check of all the various parts of the system (hoses, clamps, radiator, heater core, water pump) to see if you can find the cause of the original loss of coolant to begin with. If you are hearing water running inside the cab, check the floor and the firewall for wetness, indicating a leaking heater core.
I am going through this myself, with what seems to be a small crack in my radiator. Ahh the joys of having recently bought a used truck.

 

^^^^^And that would be go from there. How'd you make out, Cowboy? Peace, Dave.