well here we go again. 2003 600 twin fan stopped working on trail ride bird hunting. Couldn't find an issue but assumed wire damage to the sensor somewhere because I went thru some really heavy brush and fallen trees. Machine ended up starting to overheat and I was 7 miles down a trail by myself. Tried to go as far as possible and machine starting spitting fluid out of overflow jug.Inspected machine again and found thermal sensor partially unplugged. Plugged sensor in but still the fan didn't come on. Tried to go as far as possible to avoid walking home in the dark on a trail with no flashlight. Radiator cap never "blew" or released pressure but the tee connector on the bottom of the radiator neck completely blew up and ingulfed the machine in anti-freeze. Ended up walking many miles to get back to hunting camp and had to tow machine back to camp. I jumped the sensor connector and the fan did come on so I know the fan is good but the thermal sensor must be bad. This would be my 3rd sensor. The machine does still run even empty of coolant. Had to start it to get loaded in truck. My concern is that isn't the radiator cap supposed to release to avoid it blowing up parts of the cooling system? also, I have a new sensor, tee connector, and radiator cap on order. Do you think other damge could have occured? Is there anything else I should test or look at before I refill the radiator and replace these parts? Head damage??How to check??Thanks OPT because I know you will be answering....

 

Might be hard to tell if you have any damage from overheating until you replace the sensor,bleed the air from the system completely when you add coolant and have it running. You can do a quick compression check,but a good sign is that it cranked up to get on the trailer! ALSO I would pull the water pump cover and inspect the impeller before adding coolant! I've seen impellers melted from the heat and water pump seal damage. Just install enough water and run it for just a little while to see if it leaks at the weep hole before you pour in a lot of antifreeze. Other than possible piston problems(IT did crank up,good sign) the plastic,rubber parts can take the blunt of overheating also. Impeller,water pump seal, possible thermostat(just pull it out to check the rubber seal when you check the impeller also) and hoses are the main things I would look at.Radiators can be damaged from the pressure build up and leak,but If all the other things check out install fresh coolant and see how it does. Hopefully nothing major has happened.Good luck OPT

 

It seems to be all back in order. Spent the last 2 nights running the motor and burping the air out. From what I have done in the past, I have the front end jacked up and I run the machine without the radiator cap, shaking the machine and squeezing the hoses to get the air out. also starting and stopping the motor seems to help the air bubbles come up.Once I put the cap on the temp comes up and the fan works...Hopefully there won't be any other issues...

 

Kinda going thru the same thing myself with my 03 700 twin. I took the fan out thinking it was bad but when I put 12 volts to it, it worked fine. I put it back in then thought my t-stat was bad so replaced it. Not the problem. Then I discovered the sensor at the bottom of the radiator, figured that was bad and replaced it. Fan still won't come on. After reading some threads on the subject, I'm going to try bleeding air out of the system and see if that fixes it. Boy, I sure am saving money by not going to the dealer........lol.

 

On the 600, 700 and 800 engines there is a bleed bolt on the thermostat housing that make bleeding this system easier. Just fill the radiator, run a couple minutes,open the bleed bolt to purge air/coolant then close. May have to do it a couple times,but shortens the time bleeding the air out of the system. They should have had this on the 500 also,would have made it a lot easier. OPT

 

Here's a pic of where I think the bleed bolt should be. I don't see what you are talking about.

 

Sorry again! Bleed bolt offered in the cover starting on the 2005 Ranger 700XP not the Sportsmans.Shows it pictured along with the sealing washer on the thermostat housing. They added it because of the extra length cooling hoses. Not a bad idea to replace the cover on the Sportsmans with this cover.OPT

 

My problem is along this subject- i have a 04 sportsman 700 with a blown engine. Replaced it with a 2005 600. There are 3 coolant lines from the filler neck. However on this new engine the there is no fitting on the side of the engine next to the thermostat for the bottom of the tree filler neck lines. What do i do here???

 

Yes cooling systems changed along with the radiators. You'd have to mix parts from each sounds like to make it work. Here's the 700 diagram,then the 600.

 

Cant I just delete that line since the new engine doesnt require it?