Over heating problem SOLVED
 

I installed a shinny new thermostat housing today and it SEEMED to prove the "hole in the bypass theory". Stay with me here, When Bruce first talked about that ,everyone said to themselves "putting a hole :confused: in the bypass would not solve anything as more coolant will bypass the radiator and it will run hotter dah.
I posted Bruces explanation of why it works, which I still do not understand, but thats not the point. He claimed when a T stat housing gets old some of the area where the bypass sets is eroded and the round bypass "flap does not seal. (how could a hole in the flap compensate for that) It seemed like trying a NEW T Stat housing would prove his theory so heres what happened. My "80" 616 has been running a tast over 90C, not bad, not even scarry but it should be at 85C as there is 3 K on the rebuild, new 300D radiator,block clean, MB coolant, new water pump, should not still be running over 90C.(I expected it to run a little hot after the rebuild) I used the same thermostat with the arrow fwd Anyway after a 24 mile road test shes right a 85C right where my "85" 240D runs. .......It was the T Stat housing.