I just bought a used 2006 Sportsman 500 HO. The first time I took it out, it overheated only about a mile or so into my ride. I noticed it was losing power, and glanced down at the display just in time to see the "HOT" indicator before the quad died. I let it sit for a second, then turned the key back on. The fan came on and ran for about three minutes then shut off. I started the quad back up and rode it (more gingerly this time) for maybe five to ten minutes, and it overheated again. This time I limped back to my trailer stopping periodically to see if fan was running. I never noticed the fan running while I was riding.

I've read some of the other posts, and have a few things to check out (heat sensor/switch on the radiator/fan, radiator cap, thermostat, etc...). Truth is, I'm not exactly what I'd call an experienced wrench-turner, so I just wanted to get this thread started so I'd have aplace to post my inevitable questions once I dive into this.

Suggestions in advance are also welcome!!

Thanks...

 

first thing i would take the vin# to a dealer to see if that bike had the ecm recall done or if it was even covered under the recall. is the bike actually over heating(usually it will spit coolant out of the little plastic under the fender) or is it change the hot light coming on? also did you check the fornt and back of the radaitor to make sure it wasn't plugged w/ mud. you already mentined the fan was working so i'm guessing that part is fine. was the fan coming on before it over heated? just a couple of things to look at.

 

He said he never noticed the fan running while he was driving that could be the problem . Just start the bike up and let it idle in your driveway and see if the fan turns on once it heats up it won't take all that long .

 

take front rack and plastic panel off, on top of radiator is the temp sensor, turn the key on and unplug wires to sensor, fan should come on,if it if it does its probably a bad sensor if it doesnt, hook 12 volts directly to the fan, that will make sure the fan is good, as stated check on recall and make sure radiator is clean, also make sure its full of antifreeze while you have rack and cover off, , take radiator cap off and start it, let it run till fan comes on , may have an air bubble, that will get rid of it

 

What he said +1 OPT

 

Stendori:
-I emailed the local dealer yesterday asking about the ECM recall. No response yet.
-The quad did overheat. Hot light came on, coolant was boiling over into overflow res, and out onto the ground (just a little bit was actually dripping out onto the ground, not much). I turned the key off, then back on... HOT light still on, and that's when the fan came on. After it ran a few minutes, HOT light went off, fan quit running. I started it back up, and tried again. After a bit it did it again, but I caught it sooner because I was watching for it. I never did hear the fan come on while I was moving; only after I pulled over, turned key off, then back on.
-This past weekend, in my garage, I removed all the front end plastic. Let the quad idle in my driveway for ten minutes or so... fan never came on. Revved the motor a bit, no fan. Rode around the block three times, no fan. It didn't overheat, but it was warm. I felt the supply & return water hoses, and they were both pretty warm.

Kerbbirds:
-There is a plug mounted right on the top of the radiator (sort of purple looking). Is that the temp sensor? I'll try unplugging that tonight.
-I took the rad cap off, and there was coolant right to the top. I ran the bike for a minute, didn't see any bubbles. I kept thinking the fan would turn on, and the coolant level might drop, but it never did. Should I be able to see some movement in the coolant when the bike is running and the rad cap is off?

Old PT:
-I don't understand your post???

 

If you have a BLACK finned module under the front panel,could be source of your problem,this is the ecm.(Chinese) Replacements are bigger and silver colored,and I have even replaced some of these NEW SUREFIRE ecms that were bad also!. Primary purpose is for charging and fan operation. If you can't leave radiator cap off and run until fan kick on before the hot light kicks on and spews coolant, then possibly ecm bad?? Some ecms were bad PAST the recall numbers.( I replaced a few out the recall range) Recalls were for mostly 05 models. +1 meant I agreed with kerbbirds post. If air trapped is the problem,sometimes you have to let run with cap off for up to 10-15 minutes until fan kicks on,then air should be removed. If it boils out or starts spewing before fan kicks on,then ecm is likely the problem unless fan is bad,mud back of radiator,etc. As far as testing fan motor,follow fan harness to its connection and then you can apply 12 volts to fan to verify

 

yes thats the sensor, kinda sound like its got problems.probably wont see movement in coolant at idle, let me know if fan comes on when you unplug the sensor, and find out about ecm recall,they cause all sorts of problems

 

the thing about the air being in the system there refering too is if someone ran alot of coolant out of the bike and then replaced it there could be air pockets in there. by having the cap off and running it will purge it self after a while and will some times take a while. i'm guessing it's not air though as you are tewlling us the fan isn't coming on when it's suppose too. try the unplugging the sensor trick as mentioned and the fan should come right on when the key is turned on. check on the ecm as we mentioned as this part causes all kinds of isues on differnt bikes. some even had the fan kick on and drain the battery as it won't shut off even w/ the bike off and no key in it.

 

Hello all,

Finally going to be able to get back to my problem. Had a sick baby for a week and couldn't spend much time in the garage.

As an update, still having the issue. Here's what I've done so far:

Called dealer with VIN# and there are no recalls on my model.
Dealer was more than happy to sell me the repair manual for $52!! Wish I'd seen the link to PartShark.com before I made that mistake.
While at the dealer, I talked with a service mech for a bit about the problem. He was certain that the cooling system was just losing pressure because of a bad seal between the filler neck and cap. I bought a new filler neck ($28). I installed new filler neck this morning, no change.

I was reading another post on here from KEGRACING dated 07/11/2010 (http://forums.atvconnection.com/pola...lp-please.html) Sounds like the exact same thing my quad is doing. I'm going to start looking at the wiring/fuse thing. I'm even less of an electrician than I am a mechanic, so my inevitable questions will be coming shortly!!