We agree 100% that expansion is the cause for bending... And, if the bms expands, its physical length increases. This there can be no dispute. Geometrically, however, the length from the ends of the bms, relative to the mtg bracket very well may appear to have shrunk. I can see this and agree with you. Using your analogy, the ends of the "C" are closer together, even though the measured distance along the arc of the "C" will be longer than before the expansion which caused the bms to bend into your "C" shape (in the hypothetical extreme case).

Perfectly clear! Now that thats all settled, why not just remove the bms and seal the pinhole... Your fan would then be turning engine rpm until the centrifugal weight closes off the port, disengaging the fan at or above 300rpm (I think that is the speed reported by MB in my manual)? Of course, your engine would be mighty noisy, but that could be tolerated if heating could be cured by this plan. Perhaps a more flexible fan could also minimize noise as it would flatten out as engine rpm increased (and vehicle speed and air speed thru the radiator as well).

Nice discussion... I have enjoyed following this topic. Good Show!

BTW, Nice website, Jim. I am still unclear if your cool harness is applicable to my 1988 560SL...