Best location for aftermarket water temp sensor
 

I'm in the middle of redoing my 1979 GS RX-7 - build thread to come. I'm using a S4 aluminum water pump housing for the weight savings - how-to write-up to come.

The S4 water pump housing also has the advantage of having an extra port in the back that I tapped for 1/8 NPT. I also have the factory 1979 early water pump neck that has a nice flat spot that taps really easy.

If you had the choice of using the water neck, which is on the radiator side if the t-stat, and the water pump housing, which is on the engine side of the t-stat, which location is best?

Is this for a gauge or cooling fan control? Have given some thought to possible electric fan conversion as my fan clutch recently died,not bad for 32 years service. Installed another used one i had that's working fine. My 1st choice for temp sensor would be back of water pump housing,2nd radiator side of t-stat housing.

This is for a gauge. I think I'll place it in the water pump housing. Thx.

i have the probe for mechanical temp sensor that had an adapter threaded into the back of the pump housing.

I've put mine on the water pump side of the system and on the outlet neck right after the thermostat. Both worked effectively, but the location on the back side of the water pump is too convenient to pass up on these cars and easier to drill and tap I think.

Yeah, put it on the water pump housing, that way it'll read accurately regardless of whether the thermostat is open or not. That's where mine are