I have a 2000 sportmsman 500. The radiator sensor and fan are good. The problem is the flow through the radiator. I don't know if it is the water pump, clogged radiator (inside), or thermostst. The senor in the bottom right hand corner of the radiator does not get hot enough to start the fan. I beleive this is due to a water flow problem. I took the radiator cap off and put the sensor in the top of the radiator neck and the fan kicks right on. The machine will overheat after idleing for about 10 minutes. I can ride the machine for hours with no problems by running the fan with a manual switch. Any ideas would be great.

Thanks,


Jim

 

Haven't we been here before on this problem OR am I thinking of someone else? Is the water pump impeller ok,fins not worn or slipping on shaft? If impeller is ok,then have you removed the thermostat seal off of the thermostat and just put the thermostat seal back in place and tried it without the thermostat? If you have done all that I would let a radiator shop look at the radiator (if you can find one now days) only a couple left in our metroplex area! PLUS what if any parts have you replaced?? I have had radiators that had uneven heating before,but most of those were caused by air pockets in the system! Plus have you tried flushing the radiator OR wrap a towel around the neck of the radiator and shoot short bursts of air through it with an air blower? Plus can you see coolant returning into the remote filler from the engine,this system was extremely bad on having trapped air and the remote fill system had changes in hose routing(less bends) in later(2005) models when the upper engine return hose by passed the filler neck completely and went straight into the revised radiator. Just fishin? OPT

 

Mine acted like that, turned out I had a air lock in the coolant system. You can tell because if you do, if the top rad hose is hot and full but the bottom rad hose fells cool and empty.

I just added coolant to the through the rad cap as the ATV was running while shaking the ATV by the handel grip, it did a big burp and fixed itself.

Afterwards both the top and bottom rad hoses should feel hot and full.

 

Guys thanks for the help.

This is what I found so far

Radiator sensor works
Fan works
Thermostat works (1.5 yrs old and tested in a pot of hot water)
Water pump appears to be in good order and tight on the shaft
Radiator has been removed and cleaned inside and out (outside was dirty and the inside appears clean)

If it is an air bubble I will scream, but at least my radiator go a thourough cleaning.

Any more ideas.

Thanks,

Jim

 

Try like we had to do on the Rangers with the long coolant lines to remove air pockets and jack the machine up first from the front and run with radiator cap off,if still doesn't burp enough to where the fan cycles on before it gets hot,then jack it up on its side! Instructions on the Rangers to remove air was to jack up the drivers side to where machine was almost ready to tip over! (I KID YOU NOT) This we had to do many times not just on the standard Rangers,but ESPECIALLY on the CREW with hoses about 8 feet long! If you look at your model Sportsman 500 at Pure Polaris Parts Parts Catalog or Cycle Parts Warehouse under COOLING SYSTEM and compare it to the 2005 Sportsman 500 models you will see that the remote filler return line from the engine was finally eliminated and the return line went straight back to the radiator! This solved a lot of the trapped air problems with extra hose bends we and the customers had on the Sportsman 500s! Hope this may help "IF" everything has checked out as you say on the sensor,thermostat,etc!If NONE of this works its got to be down to maybe a "weak" sensor(not completing electrical path to the fan before it gets hot enough) that needs to be replaced OR the radiator itself!(PLUS you did check the sealed 10 amp fan circuit breaker under the front panel for corrosion,,etc??)Just fishin again! Good luck and keep us updated! PS: While I'm speaking about "RANGERS"-- 3 to 1 OPT

 

Thanks OPT for your info. With regards to the 10 amp fuse/breaker I dont think thats would be it, because I took the sensor and put it into the radiator at the fill neck when the machine was hot and the fan kicked right on. Unfortunatley, none of my local Polaris dealers have a water pump gasket at this time so I have to order one and wait before I refill with coolant and try those radical bleeding procedures. Do I need to use the factory gasket, or can I use an automotive type liquid gasket?

Thanks,

Jim

 

Use the factory gasket! I wouldn't trust a liquid gasket sealer under pressure! Believe me after a while these methods didn't seem radical,seemed like standard procedure even out of the crate on some of the atvs and we tested EVERY Ranger and Ranger Crew before it left the shop for proper fan operation and no hot lights! OPT

 

Thanks OPT and others for your input. I am up and runnng today and everything is working great. To sum things up: the fan,thermostat, radiator sensor, and water pump impeller were all working. The problem was a clogged radiator (internal) or an air bubble. I soaked the radiator in white vineger (inside and out). Washed the radiator inside and out. Filled the radiator very slowly while rocking the atv back and forth. Started the atv and when the thermostat opened I got a big burp of air (radiator cap was off). I kept filling the raidator slowly and when it was surging close to overflowing, I shut off the atv and the coolant level would lower. I kept doing this procedure until the level was steady. I also squeezed the hoses in a heatbeat like fashion and got air out. Lastly I jacked up the front of the machine and reved the machine (more air came out). I then topped off the coolant and put the cap on. The radiator got hot throughout and the fan kicked on. I am glad the radiator got a good cleaning on the outside as the radiator cooled down to the touch within 5 seconds of the fan coming on.

Thanks,

Jim

 

Just the design of the cooling system on these models,HARD to get all the air out!Just have to take your time and jack em up! Glad you finally got it to burp PS... Polaris should have at least installed a bleed screw on the thermostat housing on the 500s like they did on the 700 and 800 engines!This did help remove some of the trapped air at the engine and the rest at the radiator! OPT