would coolant spill out of the upper radiator hose if it was pulled off of the water neck connected to the head? i need to get the neck off to seal it because of a leak..

 

added pic

 

Yes it would, and a lot of it specially if you had the engine running a few hours before. In this case you would need to buy more antifreeze to replace the one spilling or either way you can put a can under the car to save the one that spills but I don't reccomend it, because its going to get dirty on the way down through the engine...

 

I would recomend draining the antifreeze, or just enough to lower the level, from the drain cock (I said "cock"). That way you could save it cleanly and better yet, dispose of it properly. It would be a GREAT time to just change all your coolant. The other good reason to drain it from the bottom is that it'll keep your work area and your engine cleaner.