Originally Posted by THEREALSTOREY

Sounds heat related. Things expand when hot, seals, crimps, bolts. Then things cool down and contract raising the possibility of leaking. We have Oil Purifiers here at work that leak badly until warmed up, good thing it's supposed to run all the time.
Gotta find the source, take that shield off and get it on a hoist. There is leak-stop you can put in your coolant, but it sounds like the leak is way too large.