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Discussion Starter #1
Hey every one been a while since I've been on here I got rid of my old 01 sportsman 500 and got a 99 sportsman diesel but I'm having a problem with the cooling fan it is not coming on I replace the sensor but no luck it is not boiling out of the reservoir but I did notice a small drip coming out of the hole on the right side at the base of the engine I'm guessing it's a weep hole for the water pump any ideas and does the sensor on the engine work with the sensor on the radiator to make the fan come on because my overheat light will come on but my fan will not

Thanks in advance

PS I assume the sportsman gas and the sportsman diesel are similar in cooling systems
 

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The wiring diagrams for the 1998 & 1999 500 shows a 10Amp circuit breaker in the red/white wire to the radiator thermal switch. I would guess the diesel is pretty similar in this regard.
The Red/white wire at the radiator thermal switch should be hot with the ignition and kill switch in the on position. If it's not... follow the red/white wire back from the thermal switch till you find the 10Amp breaker wrapped in a plastic pouch. That's likely your culprit.

The engine temp sensor is completely separate. It simply grounds the engine temp warning light through the sensor to the engine above XX°.
 

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Discussion Starter #3
Well before I replaced the switch I jumped the wire and the fan came on with the ignition switch so I went ahead and bought a sensor installed and rode this past weekend and the overheat light came on but still no fan .......but I was reading on another forum that if the coolant level isn't correct or there's a leak that could couse the fluid level to drop below the sensor/switch and the fan won't come on like I said in my post there's a small drop out of the weep hole where the water pump is so I'm gonna order a water pump and install it and see what happens

Side note: the reason why I don't bypass the switch and make the fan run constant is because it is a diesel and with winter coming I'd like for it to get to operating temp so it runs decent and not constantly running cool
 

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If she is overheating it could be the water pump or thermostat or both. If the water pump is weeping coolant then it's on the way out. Thermostats are cheap enough I'd do it at the same time.
Don't overlook the fact that the overheat lamp sensor may be bad. Check the actual temp with an infrared thermometer. The warning lamp sensors are cheap enough tho.

From orbit on my Android.
 

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Discussion Starter #5
do you know the actual temp should be? and is there any tricks to getting the water pump seal out with out messing up the shaft or removing the engine?
 

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At a guess 180°-200°F is normal operating temp range.
220°F is just barely overheating for most internal combustion engines with 15PSI cooling systems. Near that but above is where the warning sensor should kick on. If the light is kicking on at 200 or 210 you have a problem with the sensor.

The parts manual should give you some idea of what you are looking at.
http://pi54.com/corp/manuals/Parts/9914915r01.pdf

Just curious. Have you washed out the radiator cooling fins so you can see through them?
 
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