Well the 525it overheating problem was the cylinder head, it took me 2.5 hours to take the head off the car and realizing that the problem was a cracked from the intake valve to the cooling passage.

I will see if my machine shop can fix it, else I will need a new head.

I like the M50 non vanos engine with the aggressive cams and no vanos rattle noise so I do not really want to start a swap. And a turbo M50 will be good down the road.

Anyone has a cheap M50 head non vanos kicking around???