where did you buy the plastic coolant pipe that is leaking.. depending on where you buy or if your lucky or not his might happen
http://318ti.org/forum/showpost.php?...3&postcount=49 so check that might be why your leaking... as for when your bleeding the system try massaging the hoses to help any air bubbles out.. did you clean the ports where both pipes go in.. gunk build up in the system? coolant gets pretty nasty when is mixed with oil and it dries