735iL overheating!!!

I've had my 90 735iL in the shop twice (to the tune of 850 bucks) and I have the same recurring problem. Yesterday (at 1:45 a.m., of course out in the middle of no where) after having driven 200 trouble free miles, it started to overheat. I noticed that the radiator was hot on one side and cold on the other. I have had new thermostats, radiator removed, flushed and cleaned, new water pump and fan. Someone told me the connection at the bottom of the radiator has been a problem in impeding the flow. Anyone hear of that? What are your suggestions? Thanks for anything.

I also had that happen twice to my 1990 735iL

In my case it was due to defects in the following parts, they were old and worn out. The root of the problem was the water pump and the water hose.

EXCHANGE WATER PUMP
CORE RETURN
WATER PUMP GASKET
V-BELT 13X1040
V-BELT 13X855
FAN BELT 10X865

Check the radiator hoses too. In winter they can get exposed to all kinds of filth and corruption, causing them to rot.