I was plowing and the oil temp light came on. I let it cool down overnight. Oil temp light came on with key on (like it should), then went off for a few seconds when the engine started (again, like it should), then it came back on and stays on while engine runs, and the engine is not hot. Is there any way to test the Thermo Unit on the back of the engine before I pop $55 for a new switch? Did I fry the switch? Is this switch normally open or normally closed? Could it possibly be something other than the Thermo Switch? Relay maybe? What Think Ye? Does the light being on indicate anything other than high oil temperature?
Thank you, thank you, for the help

 

I would try changing the oil. Put in fresh oil and filter. Run the quad hard as you can. Check the color of the oil off and on while riding, if oil stays clear -light color-you're fine, if it gets dark, you are hot and the oil is breaking down. I would pull the switch, clean and test it, along with the wiring harness.

If the switch has goop built up on it, I would flush the engine and oil cooler with a crankcase cleaner for motorcycles. I don't know if the kind used for cars is safe to use in motorcycles. READ THE CAN!.

 

HeftyLefty, Thanks for the advice. I will give it a try.

 

Most likely just a bad sensor. Its very hard to overheat the air cooled motor. My 89 350(348cc) Big Bear same motor but the 400(386cc) had a 7mm stroke increase. My 350 had a really small oil cooler with no fan assist. The newer ones have larger better oil coolers with fan assist. Unless the ATV has a faulty oil pump there really is no way to over heat the motor to a dangerous degree on a air cooled motor.

 

TLC,
Thanks for the input. Makes sense. My fan comes on with the key so the oil temp light staying on makes me think it is the thermo sensor.

 

Thanks you guys, I flushed and changed the oil, cleaned the sensor, checked the wiring - light went off, fan went off - seems to operating as it should now. I appreciate the help!