i have 2 sensors on the back of my thermostat housing... i'm pretty sure on is the water thermo sensor, but i dont know what the other one is... does anyone know?
i have an S5 TII btw

 

Do you have the stock electric fan? I think that's what the other sensor is for, unless a previous owner tapped in one for something...

 

i got a jspec longblock (so its a japanese tstat housing) then i replaced the shortblock with a remanufactured one.
so do you think i would be ok to remove this other sensor and put my water temp gauge probe in there?

 

sure, as long as you don't mind it being past the thermostat in the water "circuit"- won't read right 'till the 'stat opens...

 

well, anything is better than what i have now. i am currently running with no gauge. i'll go see if by some chance it will thread in.

 

O.K., but in the interest of preventing litigation, you are hereby forewarned that if the thermostat is stuck closed, you will still overheat the engine without the gage telling you anything...

 

where else could i put it?

 

try the stock sensor location, since you refered to that system as being inop anyway...near the oil pressure sender unit...

 

the threads are wayyy off. the probe for this water temp gauge uses way bigger threads. anywhere else i could put it?

 

No, that's not right. He's talking about an S5, which has both the ECU thermosensor and the fan thermoswitch side-by-side on the back of the water pump housing, under the thermostat. The S4 has the fan thermoswitch on the top of the thermostat cover, which is what you're thinking of.

As long as you don't have the stock e-fan, you can remove the thermoswitch and use this spot for a temp gauge sender.

AFAIK there are no aftermarket gauges that have a sender that can screw straight into the stock location on the rear plate.

 

Sorry, NZ, but he said thermostat housing, not water pump housing...Thanks for correcting me...