I have a 06 700 that keeps overheating. The antifreeze reservor keeps filling up but, doesnt go back into the radiator once it cools down. Is it a thermostat issue?

 

Welcome to the forum! "IF" it's a carb model could be an ecm problem(on expanded recall list to replace) or could be something simple as dirt and mud in the radiator especially at the back by the fan assembly that could cause it to over heat. Plus does the fan cycle on and off?? You can check the fan directly with 12 volts to the fan motor. Or another problem could have is trapped air in the cooling system which you can leave the cap off,elevate atv at the front to purge any air while it's running and when the fan cycles on air should be forced out the radiator. "IF" it's an EFI 700 could be problems mentioned above with the exception that it doesn't have an ecm module but has a thermal sensor on the left side of the cylinder that can short out,but usually if they do the fan can run constantly or it can prevent power from getting to the fan.You can pull the connection from the sensor if it's an efi and the fan should kick on and flash a hot light if I remember correctly also. IF you could be more specific it would help,but you can check out the easy stuff first starting with the fan motor to see if it's bad "IF" the fan isn't cycling on and off! Plus a bad radiator cap could be the problem also?? OPT

 

Yes it is EFI and the fan does kick on and off but, it seems to run more than it is ever off. It has been doing this for awhile now and I haven't been able to figure out what is wrong. It has been so hot that it has melted the side panel on the rear fender and the underside of the seat as well. I can start it up and just let it sit and idle and it will get hot and the fan will kick on. Heck in the winter when its cold as hell out the fan will run most of the time which doesnt seem right. If there was a air bubble could you just squeeze the hose to get it out?

 

There were some problems on exhausts cracking on the 700 engine,plus I would still run with the radiator cap off to see if there could be some trapped air. Also if the exhaust pipes are ok but start turning red you may be better off having the computer reflashed which may help. Did have a few 700 and 800 efi machines that ran lean and hot. Plus have read(never have done this) that some owners have installed 800 exhaust pipes? Don't know if this was for better flow,cooling,or what? OPT

 

Another thing to check is to take the radiator out and see if it's clogged. Had to do that with my 500. There was hardened clay in the fan shroud area that was effectively cutting down about 1/4 of the radiator's ability to cool.

 

I will try and burp it and see that does anything. I have checked the radiator numerous times to see it was clogged with dirt or mud but, I don't see anything like that plus I have washed it out good too but, it didn't seem to make a difference. It just seems like there is something more going on like the thermostat or is there a waterpump on it that might be bad?

 

If it's loosing coolant other than going into the reservoir check under the water pump cover while running and if a seal is bad it will leak coolant through the weep hole at the bottom. I would try to burp it,plus if you have access to a radiator pressure tester you can pressurize the system and you can tell real quick if it doesn't hold 15 psi.. Plus if you're certain the radiator is clean,could be just air or a faulty radiator cap. You can match the cap up at any auto supply. OPT

 

Thank you much for all the help and info. I will check those things out and report back what I find.

 

Well I took the radiator cap off and start it up and let run until the fan kicked in. A few small bubbles came out but nothing that I would think would cause a blockage. I had the radiator full and after it ran for maybe a minute or two the antifreeze level went way down so I filled up again while it was running and the level went down again but, not as much. Is that normal? I filled it after I shut it off the let it sit and I just want and checked it went down again. I checked the oil but, that seems fine I think. Not sure what the oil would look like if there was antifreeze mixed in it? Wouldnt it get foamy looking?

 

Yes! This is when the thermostat opens, air pockets are being expelled also and the coolant level drops! You may have to do this a couple of times and let the fan cycle on and off with the cap off. Some models take time to remove all the air. After you've bled the system, top off the radiator,replace the cap,fill the reservoir and test drive it to see if this solves the problem. If coolant got into the oil it would be milky and slimy and about the only way would be through a burnt head gasket,plus you could smell the coolant burning also plus smoking! OPT