I have an 87 SR5, so there is a temp sensor hung off of the block or lower intake between cylinder 2 and 3, a sensor on the thermostat housing, and a sensor next to the cold start temp/time switch. I'm going to determine which is the temp gauge sensor and replace it as my stock temp gauge is useless right now (it does the SR5 standard cold or normal reading only, without moving even as temps climb high enough to boil over...)

VDO has a line of sending units that close a path to ground at or above a certain temperature. It was meant to activate a warning light, but I'm considering using it to activate a relay that will run my electric fan.

I was first interested in the one that activated at 195*F, but that is discontinued. The next step is 205*F. I'm not familiar enough with the 22RE to know if that is a safe fan on temp. I wouldn't want it below my thermo temp of 195*, but what do you guys think about turning my fans on only when the the coolant is at or above 205*. Please assume that the coolant mixture and cooling system will be maintained at a level adequate to support temps over standard water's boiling temp if they happen to be reached (i.e. good mixture, good cap, maintained hoses, etc.)

Thoughts?

 

Your t-stat is 195*F? Stock for my 3VZ and 5VZ is 180*F If you're running a 195* t-stat then I guess 205* for the fan to come on isn't too bad. I'd like to run cooler myself.

This is what I use to control my fan: http://www.ultimateyota.com/index.ph...=26&topic=50.0

 

I'd rather have the coolant in the radiator cooler than the coolant in the engine myself. It might be fine on the highway, but at low speeds you won't have much temp difference between the two to affect cooling when the thermostat opens.

 

ive got mine set at 187. i used a probe type sensor in the rad fins. also my controler is set to come on at 60% power at that temp and and will increase if needed. if it sees ( i think ill have to read it again) 20% more it goes 100%. i also have the high side of the fan switched so i can get massive cooling if needed but its never happened yet. or i can turn everything off. i used the flex a lite varible speed controler. it can be connected to block probes as well