I have not heard my cooling fan go in awhile and I did some pretty serious muddin this weekend so it was run hard. I bypassed the radiator switch and the fan worked fine. I'm not sure how to test the switch itself to see if that is the problem. Can anyone help me out? The shop manual says the temp. at which the switch relays the to the fan motor is at 180 degrees +/- 3 degrees so I ran the motor to 190 and it still did'nt turn on..
Thanks

 

Take the switch out and put it in boiling water with a thermometer. Hook an ohm meter up to the switch and turn up the heat. See what temp the switch closes (if ever). If it closes at the right temp, look elsewhere.

If you don't have an ohm meter make up a continuity tester with a light, battery and wire. But everything in series and wait for the light to come on.

 

Thanks for the reply, I did one better. I took off the front rack and pulled the temp sender out of the radiator. I set up my coleman stove and heated the water up with the sender hooked up to the fan. Submersed the threads of the sender in the hot water and progressivly heated the water with the thermometer and sender in place. The fan started at 191 degrees. The Shop Manual says the thresholds for the sender are 180 degrees +/- 3 degrees. I guess I'm wondering if this is to hot for the motor or should I just leave it alone.

 

How accurate is the therometer that you used? I don't think 7-10 degrees would make that much differnce but I don't know. If the switch is cheap (under$10) I might just put in a new one.

Good luck

 

The switches arent that cheap, about $50.00 in my area. But they dont last forever, mine only lasted about 7 months. But I got the dealer to cover it under warrenty since I bought my quad in late fall and it sat unused all winter. And when I broke it out in spring, the fan wasnt working.

 

Guys--if I could offer up some advice (from a guy who had to pay to get a whole new head gasket put on his SP500) KEEP THE RADIATOR CLEAR!

If that red engine light comes on---STOP IMMEDIATELY!

I didn't, and boy did I pay a price.

 

I will second that, been through a head gasket and honing and that ain't fun being down on a sweet weekend for zipping around the woods on a hopped up scrammie.

I actually hooked my fan up to run all the time, now I don't have any worries about overheating from the fan not working (yeah hillbilly I know). Actually the old fan blade ejected somewhere down the trail once but the motor stayed in, don'w know why other than a cheap fan or something but that is another story.

Balzak
2000 scrambler 400 2x4
More mods than Fabio has said butter