My radiator fan does not always turn on and as a result, the engine will overheat. When this happens, I pop the hood and the just give the fan blades a little "tap" with my finger, and the fan motor starts right up and spins, and then the engine cools.

Two things I did recently (this was not happening before):

Replaced the starter (from below)
Drained the coolant and replaced with 50/50

Any suggestions? Is the motor bad? Could it be a sensor?

 

If the fan motor is not sticking and you having to assist the motor to start it turning, I would suggest you can rule out the sensor because it sounds like you have an armature winding broken.
Kev

 

Thanks Kev. The fan motor moves very freely when I spin it when the motor is off.

I wonder if I may have damaged it somehow. While I was replacing the starter, I had an led flashlight/worklight propped next to the fan area. Do you suppose I may have disconnected something or ...?

 

Have you tried putting a live feed and earth to the motor off engine?

Regarding your question – Led flashlight/work light propped cause the problem!!!! In my opinion no way would this cause any issues.

Kev