bmw 528i?

I.ve got a 528i E39 touring model bought last year March 2010 with overheating problems
we have changed the water-pump,3 rads 2 thermostats and a 2nd user engine,temp gauge says cool water like soppy suds coming out of of the rad.I'm getting really fed
p now and my machine says hes had u=it up to his back teeth,i need help