Hi all, I have a 2001 sportsman 500ho. On a labor day quad trip it began to over heating. When I got home from the trip I removed the radiator and washed it and checked for flow which was good, next I pulled the thermostat and put it in a pan of hot water and it opened as it should and last I pulled the water pump cover and hit the starter and it spun. So, any input would be great guys thanx.

 

Notice any leaks at the bottom of the water pump housing drip hole(water pump seal) before you removed the cover to check the impeller? Usually thermostats aren't the problem. Trapped air pockets in the cooling system,clogged radiators especially around the back by the fan. Since you've taken the radiator off and cleaned,established that the thermostat and fan sensor is ok(fan kicking on) I'd lift the front end,leave the radiator cap off and let the fan cycle on and off several times to remove any possible trapped air pockets.This may take upward of 15-30 minutes at times. Wouldn't hurt to replace the 13 psi cap at any auto store. A coolant pressure test may be needed if the machine still over heats.If it wont hold 10 psi you have a leak some where.If it's gotten hot enough a head gasket can blow and leak coolant into the combustion chamber.

 

I will have to try that when I reassemble the machine. The oil looks good (not milky), the machine cools off fairly quickly and only bubbled the overflow once.

 

Well I reassembled it and now the fan will not kick on and with a charger running the fan the light still comes on. I checked the hoses and they were warm not hot.

 

I guess I will change the sensor in the radiator.

 

Is the battery bad? If it is the fan won't come on. Check while running that the battery is charging 14-14.5 volts. If not the battery can be drained down and not have enough power to trigger the fan even if you have the battery on a charger. Load test the battery,replace it if needed.

 

Well I didn't have the front grille/rad cover bolted on so I don't thinknow the regulator was grounded.

 

It doesn't have to be grounded. Just make sure all wires are connected and that the battery is receiving a charge. If not it could be a regulator problem.Even if it is charging correctly a battery doesn't last forever and may not be able to take a charge. A simple load test can tell if it's good or not. This could be the problem and may not be sensor related.

 

Battery has 11.5 and running it's over the Rev it is at 14. Ish. So the regulator is working properly.

 

Sounds good. If you've put 12 volts to the fan itself and it's ok you can also check the sensor by checking ohms resistance when cold and when hot. Resistance should drop when hot. If resistance doesn't change when hot the sensor has shorted. You might then give one of these a try if you don't want to spring for a 60 buck oem sensor. Heat Sensor Switch Fits Polaris Sportsman 500 2000 2001 2002 2003 2004 | eBay Make sure though that you've bled all the air pockets from the system. Some take a while to work all the air out.