My engine HOT light keeps on coming after only about 1 hour of use on my 2005 Polaris Sportsman 500 H.O. The radiator is perfectly clean. The coolant level in the reservoir is just fine. Now i opened the pressure cap and didn't see any coolant. Is that normal? Fan works great and nothing blocking it. I was thinking maybe it could be the thermostat. Thanks

 

Welcome to the forums OverthehillsgangATVer.

Possibly the temp sending unit? Is the overflow bottle losing fluid too? I'd check the oil and make sure that's not where it's going.




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If it has never been checked before your problems I would fill it & keep an eye on it. With it full you should be able to run it w/o the cap & see coolant flow, that should tell you if you are getting circulation. No it isn't normal for it to be down. Might also want to check your weep hole on the water pump, it may be seeping out there.

 

I'd say you have a leak somewhere. An empty radiator isn't normal. Is your exhaust white?. White exhaust means water in the cylinder, which means head gasket is gone; which means warped cylinder head from heat.
Empty the radiator and remove it. Have a radiator shop clean it and pressure test it for leaks. Reinstall it.

Go to the autoparts store, buy a gallon of 50/50 antifreeze and water. Raise the quad in front til the radiator is straight vertical. Fill it with the 50/50 mix. Secure the quad so it stays in place. Start it up and let it idle, keep the radiator full. Once the engine gets hot, the thermostat should open, letting the cool water into engine. If it does, the thermostat is fine. If it don't, check thermostat and water pump. Check for proper fan operation, check radiator and all hoses for leaks.

If all this looks good, replace radiator cap. It could be bad.

My best guesses.

 

ya the coolant in the resavoir is between the min and max when it is cool. when the engine has been running for a while it is at the max. I let the ATV cool down and then checked it. thats when i saw no coolant in the pressure cap

 

I dont know what kind of coolant is in there at the moment. I don't know if it's the Polaris 60/40 or 50/50 mix. Does it matter? Can I mix and match?
Thanks Everyone

 

The old ladys did the same thing.You wont believe this ,but take off the metal grate,and screen in front of the radiator.You cant see it unless you do,but hers was packed with mud,and you cant wash it out unless you remove it.The screws are a bugger.bet thats it.
ALAN

 

I have a 2005 sportsman 700, and my dads 2004 500HO both did the same thing 2 weeks ago. I checked and replaced the antifreeze, pulled out the thermostat, replaced the radiator cap, checked the fan and still after about 1 hour it started flashing hot again. The radiator looked clean from the front and the back looked a little dirty but nothing bad or so I thought. I finally decided to remove the radiator and found I was 100% wrong. The fins were packed at least 85% of the radiator. My 700 has around 1600 miles and looked to have never had radiator cleaned. My dads 500HO only has about 102 miles on it and I got him to pull and check his radiator and he found that he had the same problem. My bet would be that if you pulled the radiator and gave it a good look you would find the same problem. It's to hard to see if you don't pull the radiator out. Good luck.

 

what in volves taking the radiator out? What about the no antifreeze in the pressure cap? did yours do that? thanks

 

A quick check of the condition of the back of the rad is to remove fan & shroud (4 10mm bolts & the wire) and you will be able to see behind easier. Removing the wheel helps too. As for why the rad was lo it may have spewed out of the overflow bottle when it overheated. Took mine out once and yes it was very plugged behind. Will need new coolant also cause even trying to be careful there was debris falling in it when I drained and did not want to chance putting back in.