I've been chasing a cooling gremlin on my Cousin's 91 535im. Long story short, we've done the head gasket, t-stat, and converted to an electric fan. However, the darn thing is still overheating after repeated bleeds. Out of dumb luck, I happened to put my hand on the radiator and realized that only the top 4" of it was hot, the rest was absolutely cool to the touch (after 10+min of running). I'm assuming that indicates some sort of blockage? I've never heard/seen/felt it be that severe. Is there anything special about these radiators that would prevent me from going to a local radiator repair place and having them clean it? I'd hate to drop $150 on a new one if it's not needed. Thanks!
-Lloyd