The water filler neck i got from the j-yard has a temp sensor it in (maybe a thermal switch,). My car didnt have one stock, but it has the little green wire that goes to it... what is this sensor for? what would happen if i pluged in my green wire?,.. just curious,.. im probably going to use it for a temp gauge either for my electric fan or my temp gauge on that side of the thermastat.

 

It's the temp switch for the optional factory auxiliary electric fan. If you have no switch on your old filler neck then you have no fan, so plugging in in will do nothing. It's on the wrong side of the thermostat for a temp gauge.

 

I have a temp gauge mounted on that side to check what temp the thermostat opens and the temp comming out of the motor allready. what temperature does it activate at? Thank you.

 

One reason you're supposed to mount temp guage senders under the thermostat (i.e. engine side) is in case the thermostat sticks closed. If this happens and you're measuring the temp on the other side of the thermostat you'll read a cold temp while the engine overheats and cooks itself. You won't know until it's too late.

The fan temp swich is a normally closed switch that opens at 207degF and closes at 194degF.

 

Way to hot, thank you. Im aware of that, but i like it on the rad because i can see the opening temp of the thermostat, ive experienced what you are talking about a few times, but can usually catch it by the riseing stock gauge and low rad gauge.