Why is My Polaris Sportsman 850 Overheating?

If you have a Polaris ATV that’s over a decade old, and the radiator is clean and the cooling fan works but it’s still overheating, the culprit is likely to be the thermostat.

Partzilla’s Polaris ATV expert John Talley hosts live Q&A sessions on our YouTube channel every Friday at 3pm Eastern. In this session, John was asked what could be causing a 2009 Polaris Sportsman 850 XP with a working cooling fan and a clean radiator and coolant to overheat after an hour or two of riding.

Polaris Sportsman ATV Overheating Q&A

Hey John, I have a 2009 Polaris Sportsman 850 XP that overheats after about 1-2 hours. The fan is turning on and the radiator is clean, so is the coolant fluid. What do you think is the problem?

John Talley: Well, what kind of shape is your thermostat in? That would be an easy thing to replace. Your machine is an ’09 and we’re coming up on 14 years of age, so chances are the problem is going to be the thermostat.  

Watch the video below to see how to do an engine compression test on a Polaris Sportsman 850 ATV.

Watch the video below to see how to do an ATV coolant flush. 

Watch the video below to learn about some of the reasons why engines blow up.

Want to see more live repair questions answered? See more motorcycle and ATV repair questions answered here.