Yesterday I was riding my 2009 RZR 800 EFI and the temp gauge jumped up and pegged at 300 degrees. My engine was not that hot. I turned it off right away and let it sit until it was cool to the touch. Turned the key on and needle was still pegged out. plenty of coolant and oil level looked good. Only 60 hours on new engine. I have read that it may be a thermistor issue but cant find much info on this. The thermistor looks like an easy part to replace but don't want to through money at something that isn't the problem. Any knowledge would be greatly appreciated.
MontanaWilson
The 2009 800s only has a “HOT” warning on the dash cluster so if you are seeing 300 degrees you must have some kind of an aftermarket temperature gauge? I put an aftermarket temperature gauge on my 2009 800s, it has it’s own sending unit, I drilled and tapped the thermostat housing to accept the sending unit. The instructions for the gauge said not to use Teflon tape on the sending unit threads because the unit needs to be grounded to work, you may have a bad ground at the sensor as sandblaster suggested. I think the thermistor MontanaWilson is referring to is the sensor for the stock dash warning light so testing or replacing probably won’t solve your problem.
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Flying59, that makes more sense. I never did get a hot warning in my cluster just a funky reading on my guage. I bought used so I did not know it was after market. Do you have an illustration to show where the thermostat housing is? Can I get to it easily enough? It has worked for the two years I have had it, any guess why the ground would go bad now?
Thank you both for taking the time to talk me through it. This my first OHV of any kind and have a bit to learn.
Thank you both for taking the time to talk me through it. This my first OHV of any kind and have a bit to learn.
The thermostat housing is on the clutch side of the motor, you have to pull the seats out and remove the rear service panel, just like you were checking the oil. I drilled out the coolant bleed screw and tapped it for the sending unit. You might have a problem with the wire from the gage to the sending unit being grounded, it appears that as the sending unit gets hotter it has less resistance causing the needle on the gage to move farther the hotter it gets, at least that’s what google says. If the wire is damaged and is touching a ground or if the sending unit shorted out it would peg the gage. I have an electronic copy of the service manual, I can send it to you if you give me your email address in a conversation.
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From google
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