My 2002 Sportsman 500 overheated on the weekend.

I jumpered out the temp sensor in the lower rad and fan ran all the time....I added coolant and used it for the weekend and had no more overheating problems.

I changed sensor today.

I added coolant.

Ran bike with rad cap off and purged air from system....I even jumpered fan and watched coolant go down and then added a little more while it was running.



Now the fan will still not kick in.

I have 12 volts to one side of sensor(off with key switch on), and 14 volts running. But never get 14 volts on other side of sensor, so that sensor is not closing.

IF I leave the bike idling it eventually starts to heat, red light will come on dash, and it will boil coolant out of reservoir.

IF i jumper out temp sensor fan will run all the time and machine will run fine, I took it on 40 mile bike ride on the weekend and no problems.


My next step is to test the old sensor in a pot of boiling water to see if it will close.



If it was still good then is there something in my RAD? Blockage?

last resort will be to pull the new sensor and test it.

This seemed like a simple problem that is turned into a real head scratcher???


I got took for $85 dollars for a bum sensor?

 

Update.

I tried different rad cap....no change.

I tested old sensor...N.F.G

I tested NEW sensor.....O.K.

Put sensor back in and refilled...purged.....and O.K?

Fan kicked in.....

My guess is I never got all the air out when I purged it the first time....and it was air locked.???

 

Yes the 2002 models (up to the 2005 models when the system changed) was one of the hardest to purge the air from because the radiator return hose went back to the filler neck instead of the radiator directly. You can purge it for awhile and think you have all the air out,but they can overheat. I've spent more time purging air from the systems than in replacing the sensor,filling the radiator,etc. Glad you solved your problem. OPT

 

Well it happened to me again...worked my 2002 a little hard going ice fishing and when I got back to truck it just started to bubble over...fan was running which was weird...but now fan sensor is capoot again. I jumped it out and idled bike and burped the air out of system but cooling sensor NFG again!!! Good news is didn't blow head gasket and red heat light did not come on.

Was not a big deal but had fishing trip planned for next day....so was kinda bummed out. I thought I could take my wifes bike (2007 Sportsman 500), I had used it for icefishing last week and took it for a test ride before I loaded it and low and behold its fan won't come on either same affliction.

I am pretty upset at these Sportsman 500s always failing other guys had bikes out under the same conditions and no problems for them?

WHY do these coolant sensors always fail when the bikes are worked?

What is the solution?

I do NOT want to keep replacing these sensors at $90 a shot.

Any ideas?

I was thinking of of adding a manual over-ride switch and analog guage for engine temp.

Does anyone know of a simple system to install, maybe an inline thermo-sensor that can be installed in rad hose?

To me these sensors are improperly calibrated and they do NOT turn fan on soon enough and by the time they do they have burnt themselves out.

Or should I just add manual bypass switch and leave fan on all the time when I am working the bike hard?

I checked my rad fins and they are completely clean.

Is there a thermostat on the engine block or is coolant circulating all the time?


One thing is for sure I am so DONE with Polaris bikes....too unreliable!!!!

 

I found this kit...I am going to order 2 of them and install manual bypass switch for the fans.

Electric heat temperature gauge for snowmobile and ATV.

 

Don,t buy a rip off sensor from the dealer. Go to any auto parts store and say you need a rad thermal sensor for a 84-88 Nissan Maxima or 86-89 Nissan Stanza.

BlueStreak TS-127
Wells SW526
Both work for $30.

If the top Rad hose is hot and hard but the bottom rad hose is soft and cooler that mean you have a air lock.
I had that happen to me, took a while to burp the air out. Drove me almost nuts.

 

I can locate engine high temp sensor on the 2007 but cannot locate coolant sensor.

It is not in rad or rad hose, checked by water pump and thermostat.

Anyone know where coolant sensor is located?

 

I thought we were talking about a 2002 Sportsman?(same as my 2001)
The sensor screws into the bottom corner of rad.

 

Yes my 2002 has same problem, BUT I also have 2007 that is acting same way. IT does not have rad sensor, only sensor I could find on the 07 is just below thermostat on engine block. If I unplug sensor the fan comes on and speedo needle flashes and display reads engine hot.

Both bikes rads are clean and I have been reading 1000s of posts/threads on Polaris bikes overheating???

Keep in mind that I am riding in Snow and slush right now so ambient temp is alot cooler yet these bikes are still over-heating....MAJOR p.i.t.a when the Hondas and Yamahas are running is same conditions and no problems.

 

Check at room temperature(68 degrees) that the temp sensor ohms out at approx 37.3K ohms. At 212 degrees should read 2.1K ohms resistance. You can do this with a cup of boiling water. If it tests within range a simple 13 psi cap might be the problem. Plus if you have access to a radiator pressure tester, the cooling system must hold 10 psi with no drop.
If you remove the sensor or replace it,jack the front tires up and let the fan cycle on and off several times to purge any trapped air.