3.0i coolent leak help please!

[bf15]

Hey guys we just bought a 2007 e70 with the 3.0 in it. Ive been trying to find a coolent leak. i broke a plastic y in my vent tube in the process, and replaced that today and refilled, and put a new cap on the expansion tank.

well anyways, i tried following the directions i saw online for bleeding the coolant, but i cant find any specific to the engine in my car, and they all referenced a bleed screw. I cant find this on the reservoir, or near any of the radiator lines. This being the case, am i supposed to just the radiator cap off to bleed the coolant?

Anyways i went through the bleed procedure a few times leaving the cap on, and then took it for a test drive. when i got back home, there was a leak spry from the side of the expansion tank.

Im guessing either i did the bleed procedure wrong, or.... when i put the new cap and vent line on, this made it better able to hold pressure and exposed the small crack where it had already been leaking all along.

Thoughts? tips?