Hello, my name is XXXXX XXXXX X can help you with your question.
While I'm not sure what model of gator it is you have I'm assuming that it is a 6x4, the cooling system is fairly basic. The air purge plug that you are looking for is located on top of the middle of the intake manifold. With the engine running loosen the bleeder screw until only coolant comes out and snug it back up.
The electric fan is turned on by a temperature switch (#13 in the attached diagram). Check the connection on switch and wire wires leading up to it. If you have a ohm meter the temp switch should be open when the engine is cool and closed when hot.
One other issue that we have started to see on older gators are the water pump drive gear fails. The water pump bearing will get loose causing the drive gear to ride high and strip the teeth off as the gear is plastic. If your water pump has failed you will find the radiator and hoses at the radiator are cool when the engine is over heating.
With any luck this will help you narrow down the source of your problem. If this has answered your question please hit the green "Accept" button so I get paid for helping you. If you need further assistance please reply to this message and I will be more then happy to help you out.
My apology, I assumed it was a gas engine.
On the diesel engine there is a bypass tube leading from the thermostat back down to the water pump. It is the responsibility of the bypass tube to help force air up and out of the system. In short the diesel is supposed to be a self purging system. If you filled the engine with coolant via the thermostat housing as you described that would do a exceptional job of filling with out risk of trapped air.
I personally have not had much trouble with the water pumps on the Diesel gators but it still wouldn't be a bad idea to check the hoses to make sure the water pump is flowing coolant.
I have attached to break down of the diesel water pump just as a visual reference.
Let me know what you find.
It sounds like your problem revolves around the cooling fan. Unfortunately I can't give you the wiring diagram due to copy right but I can help you with the wire routing.
The F2 fuse is responsible for supplying power to the cooling fan motor. The supply fuse does not supply power to any other function on the gator. The red/blue wire (this would be the wire on the machine harness) that goes to the cooling fan should be hot all the time via the F2 fuse.
The cooling on off is controlled from the ground side by the radiator core temp switch. The black wire on the cooling fan goes directly through the core temp sensor and the core temp sensor ground lead is grounded to the frame by a eyelet.
The diagram that I have for your serial number gator only shows the cooling fan to have two wires, one red and one black. The red wire goes to a red/blue wire in the main harness and the black wire goes to the black wire in the harness. You should be able to make your cooling fan run by simply grounding the black wire to the frame. If it does not run then the F2 fuse is blown. You indicated that when it is hot you can make the fan run by putting power to the red wire. This would indicate that the core temp switch is working and the fan motor is good. I'm guessing that you have a blown fuse or a broken wire.
Interesting fact, your gator is the first machine to roll off the assembly line for its model year. The 8807 gator serial number is XXXXX noted as the changer over from the early style wiring system to the late.
The fuses should be located under the drivers or passengers seats.
Keep me posted.
I would agree with your conclusion, it sounds like the fan motor itself has failed. I'm glad to hear you have gotten to the bottom of the problem.
The radiator core temp sensor threads into the radiator. It should be reinstalled with Teflon tape. You asked about a good wire cleaner in one of the previous posts and I forgot to answer. While I prefer John Deere Electronic contact cleaner brake and parts cleaner will also work.