by Terry Sayther
At speeds over about 30 MPH, the cooling system has no need for the belt driven (or any other) fan. That's simply because air pressure at the radiator from the car moving is enough to cool the engine. So we can just unscrew the fan and fan clutch and throw it away!
Of course, as soon as we get in line at the local Burger Doodle©, the temp is likely to head toward the pink, so we'd best do something more. We could (1) wire up the aux fan so that it runs all the time, or (2) wire up the aux fan so that it works with a toggle switch, or (3) trust the aux fan to come on automatically when the temp reaches the thermo switch 'at on' temperature (92° C stock). None of these answers are perfect, though any one of them would do the job...
Is there a better way? Thought you'd never ask! Since we've now removed the A/C from the Lemon Bimmer, we're attaching an E34 aux fan directly to the radiator using wire ties. (That aux fan is bigger and has more modern blade design) We're also raiding the junkyard again for a single stage thermal switch (Part # 61 31 1364 272/82) that turns on the fan at 82° C and goes back off again at 75° C. We've wired this switch to the high-speed side of the fan resistor. And that should take care of our cooling needs if we EVER slow down.
One less power robbing accessory!