Cooling Fan FAQ
compiled & edited by Kristian #562
Please read the Disclaimer before attempting any work in this FAQ.

Updated 15 August 2004


Manual Fan Switch

Want to be able to switch on the cooling fan at will? Just install a switch!

Remove the stock spade connectors that are seen in the first photo.


Use a “Leatherman Tool” file or something similar to widen the plastic opening (see second photo) enough so that double spade connectors can be installed (as seen in the third photo).


Run additional wire of the correct gauge to the underside of the dash.


Carefully mark and drill an opening for a toggle switch (as seen in the fourth photo).


Caution: only attempt this if you like to tinker.

Q. My fan cables have the annoying habit of vibrating loose from the switch, causing the bike to overheat during my summer city rides. I am tempted to just short the cable and leave the fan on all of the time. Is there any downside to this (besides a little noise and power consumption)? Mason #631
A1.  Andy Leeds UK #982

Fan Not Working


Things to look for #1

Andy #982


The Fan Switch is the first culprit. (The large one with the wires attached). Some owners fans did not work from new. Only 5 and 20 minutes to replace.

The general procedure is just remove the wires, unscrew and replace before too much coolant runs out. Top up the coolant and reconnect.

I now have a rocker switch in parallel to the temperature switch to act as a test/back-up. This problem has apparently also surfaced in the GS.Check also the Thermistor is working. For a Cheap Fan Replacement See Flash's Fan Replacement FAQ.

Things to look for #2


Problem: '97 F650 Radiator Fan Motor apparently burned out.


Also Check:

Replacement FAN Links:

Sizes Not yet confirmed for F650

FANally Fixed – A cheaper solution to buying the BMW replacement Radiator Cooling FAN.

by Flash #412
Please read the
Disclaimer before attempting any work in this FAQ.

  1. Take the tank off the ('94-'00 carbed F650) bike. You can do it with the tank on but trust me, it'll be LOTS faster to do it this way. Cut the wire tie that holds several wires to the fan. Remove the three "big" Allen screws that hold the black plastic frame to the radiator. Push the tab on the wire connector and disconnect it. Remove the fan assembly. Pay attention to how the puke tank hose clip mounts and the metal shroud, too. Remove the fan assembly from the bike and take it to a work bench. Don't lose the metal bushings that go through the rubber grommets.
  2. Remove the three little Allen screws holding the motor to the frame. Take the thing out of the frame. Set the frame aside. Unscrew the nut holding the fan blade to the motor. If the shaft spins, scotch the fan by jacking it up off the motor with a screwdriver. After you get the nut off, use two screwdrivers to jack the old (black) fan off.
  3. The new fan is white plastic and is meant to spin the other way. You gotta do some electrical work to make it spin the right way and some mechanical work to get it on the shaft.
  4. Look down into the connector where the spades come out. Take a small jeweller’s screwdriver and shove it in the side with the tab. Gently pull on the wire while you do this. The spade WILL just slip out of the plastic connector dealie. Pay attention when you do the second one which one came from where because you want to put them back in the OPPOSITE slot. You'll need to carefully bend the tab back out slightly before you slip it in. It'll just click into place. Do the other one, too.
  5. Remove the metal clip from the new fan. Take a file and file down the place where the clip was until that hub area is "flush" with the outer hub when viewed from the side. Basically, you want to remove about as much height of plastic as the clip is wide. Take about a half inch drill bit IN YOUR HAND and carefully ream out the hole from the side opposite the clip. You're looking to relieve it less than an eighth of an inch. It might help to eyeball the thing a few times as you go...
  6. Press the motor into the clip side of the blade with the blade sitting flat on the bench. Take a look at the other side and see if you can screw on the nut at all. If not, more reaming. If so... use your judgment. When you've got it all so it fits prepare for final assembly.
  7. Get some grease and apply it to the area that the fan hub will contact on the motor housing. Reinstall the metal clip on the hub nub. Press the motor back into the blade as before. Recheck that you can get the nut on. Put a drop of Loctite on the threads and screw the nut on. Do not over tighten. You want to be able to turn the fan without a WHOLE lot of resistance. Some is ok. You can test it by plugging it back in, shorting the switch wires and turning the ignition on. The fan blades should spin clockwise as viewed from the motor side of the blades. It should spin fairly straight.
  8. Before I did the final reinstallation, I put some RTV silicon sealant over the nut to keep it in place in case the whole mess got loose for some reason. Probably overkill. But hey, I had the stuff handy, so better safe than sorry.
  9. Reassemble in reverse order. Wait for the RTV to vulcanise. Go ride.

    What I found was that with my original factory part, when the fan came on at idle it would cool the motor until the fan cut back off. With the new, five blade instead of six blade part, the thing heats up to where the fan comes on and then... stays there. According to my temperature gauge, it doesn't get any cooler, but it doesn't get any hotter either. Frankly for $188 difference, that is plenty good enough for me. You can buy a whole WEEKEND of riding, including motels with the $188 you didn't spend for a new fan. I hope you enjoy thumbing your nose at BMW (and their usurious parts prices) as much as I do.


Q: To be quite honest, I don't think i've ever heard my fan come on!,is there a quick way to check? Can it be tested by leaving the key "on" after a ride and using just the kill switch to knock out the engine? T-N

A: 1. you can get your fan to come on if you just leave the engine idling for 5-10 minutes in a sheltered place so theres no cooling air going going through the rad, so the fan will eventually come on.

2. Yank the wires off the fan switch, that's the thing with TWO wires on it at the thermostat housing. Short the two wires together with the ignition on. You can use a paper clip for this. The fan should come on. If it doesn't, give it a little helper spin, to make sure it isn't bound up. (If it won't spin at all... you're gonna spend too much money for a new fan.)

Feedback on Broken Fans