Radiator or coolant pump?

[franks]

I just bought a 92' 750IL, 144,000 miles. I flushed the system last weekend and little pieces of soap looking stuff came out. I do not know way the stuff was in there because I have no signs of a bad head gaskit.The temp gauge with the AC on will go up to the 3/4 mark. I jumped the high speed aux fan so it stays on and it still goes to the 3/4 mark. This is only in traffic and below 40mph. If I go faster the gauge drops to the 1/2 mark. I also put a new t'stat in. The fan cluth seems fine. I am thinking it is the radiator or coolant pump. There are no leak at the pump. Any ideas? I need help to figure this out. Thanks.

[shogun]

see my comments here
http://www.bimmerboard.com/forums/e32/page/0

This is only in traffic and below 40mph. If I go faster the gauge drops to the 1/2 mark.

In my opinion very typical for failing visco clutch.