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I’d had my 2011 Big Red 700 a couple of weeks and noticed the fan hadn’t kicked on. I searched for some time to determine the temp the fan should kick on and how to know if the system is functioning properly but found no comprehensive test process. So hopefully someone can benefit from my experience.
Bottom Line Up Front: When measured with an infrared thermometer at the water coolant sensor on top of the block, my fan kicked on at 206 F.
First, here’s some info about the system. The fan is a 12v electric unit mounted directly behind the radiator. It is wired through the fuse box located under the hood over the right (passenger) front wheel. There are 2 engine mounted sensors (oil temp and water temp) in the fan circuit that “tell” the fan to come on. The oil temp sensor is beside the oil drain plug and the water temp sensor Is toward the top of the engine (where the water line enters the block). There is a 2 wire connector at each of these sensors and when either of these connectors is disconnected, the fan will run (assuming the key is on).
This is a great way to see if your fan (and associated wiring) is capable of running. Simply disconnect the sensor and turn the key on. If your fan comes on, you’re half way home.. If you’re fan doesn’t come on here, there’s something wrong with the fan, fuse or associated circuitry. It doesn’t mean your sensors are good, it just means your fan can’t operate even if the sensors “tell it to”
So back to the procedure to test your fan circuit and sensors.
1- Crank the machine and ride it around 3 minutes to warm it up.
2- Use an infrared (IR) thermometer and measure the temp at the water coolant sensor. Check it every few minutes as it rises to operating temperature. Mine started at about 145 after the 3 minute warmup ride.
3- Use the same (IR) thermometer to keep check on radiator temperature as the engine continues to idle
note: As the engine continues to approach operating temperature, the thermostat (just above the Water coolant sensor) should open at about 176-183 degrees. The radiator temp will then begin to increase more rapidly. Using the IR thermometer, my radiator temp lagged behind the coolant sensor temperature about 5 degrees throughout these measurements. I also kept a check on the oil temp sensor but it lagged behind water sensor and radiator temp.
4- When the IR thermometer read 206 degrees at the water coolant temp sensor, my fan kicked on. The oil sensor was at about 185 F.
I should note here that my machine stayed around 200 F for some time with no fan operation. I had to run the RPMs up 3 times to get it up to the 206 F but once there, the fan came on long enough to cool down to approx 200 F then went off.
I wouldn’t go over 207-208 F with this test. At those temps you’re approaching the boiling point of water and are above what I would believe to be an acceptable operating range.
I have a 2011 Big Red but suspect this info can be applicable to other models.
I’ve read where on some machines (Rincons??) water and oil temp sensors are single pin connections and disconnecting the plug and grounding it will actuate the fan (with key on).
hope this helps.
Bottom Line Up Front: When measured with an infrared thermometer at the water coolant sensor on top of the block, my fan kicked on at 206 F.
First, here’s some info about the system. The fan is a 12v electric unit mounted directly behind the radiator. It is wired through the fuse box located under the hood over the right (passenger) front wheel. There are 2 engine mounted sensors (oil temp and water temp) in the fan circuit that “tell” the fan to come on. The oil temp sensor is beside the oil drain plug and the water temp sensor Is toward the top of the engine (where the water line enters the block). There is a 2 wire connector at each of these sensors and when either of these connectors is disconnected, the fan will run (assuming the key is on).
This is a great way to see if your fan (and associated wiring) is capable of running. Simply disconnect the sensor and turn the key on. If your fan comes on, you’re half way home.. If you’re fan doesn’t come on here, there’s something wrong with the fan, fuse or associated circuitry. It doesn’t mean your sensors are good, it just means your fan can’t operate even if the sensors “tell it to”
So back to the procedure to test your fan circuit and sensors.
1- Crank the machine and ride it around 3 minutes to warm it up.
2- Use an infrared (IR) thermometer and measure the temp at the water coolant sensor. Check it every few minutes as it rises to operating temperature. Mine started at about 145 after the 3 minute warmup ride.
3- Use the same (IR) thermometer to keep check on radiator temperature as the engine continues to idle
note: As the engine continues to approach operating temperature, the thermostat (just above the Water coolant sensor) should open at about 176-183 degrees. The radiator temp will then begin to increase more rapidly. Using the IR thermometer, my radiator temp lagged behind the coolant sensor temperature about 5 degrees throughout these measurements. I also kept a check on the oil temp sensor but it lagged behind water sensor and radiator temp.
4- When the IR thermometer read 206 degrees at the water coolant temp sensor, my fan kicked on. The oil sensor was at about 185 F.
I should note here that my machine stayed around 200 F for some time with no fan operation. I had to run the RPMs up 3 times to get it up to the 206 F but once there, the fan came on long enough to cool down to approx 200 F then went off.
I wouldn’t go over 207-208 F with this test. At those temps you’re approaching the boiling point of water and are above what I would believe to be an acceptable operating range.
I have a 2011 Big Red but suspect this info can be applicable to other models.
I’ve read where on some machines (Rincons??) water and oil temp sensors are single pin connections and disconnecting the plug and grounding it will actuate the fan (with key on).
hope this helps.
