My bmw 525i e60 2008 overheats.

[Threatexp]

I did a headgasket and a valve cover gasket replacement, after that i also got a new water pump, did the timing and all stuff. The first start was crazy. After that my car overheats on idle, and when i drive it for like 5 minutes the coolant starts coming out of the expansion tank. I dont know what to do. I am out of funds and out of mind. Please help.!🙏🏻