theres a cooler inside the radiator that the lines flows in and out of.
when you loosen the bolt up you can push it and the tank in, maybe the seal didnt line up right when you went back on? not sure.
if you have a metal clip in the bolt, one end has a loop you can pull the clip out, or theres a tool that you slide on the line into the bolt/fitting and it releases the metal clip.
the line end is for lack of a better work, "dick head shaped" lt made like that so you can push the line in through the clip. you'll feel and hear it click, then try to pull the line out to make sure its locked in.
