Coolant temperature sensor.

I installed mine (QV) in the block below the plenum. The location was previously occupied by a sensor for the Bosch system.

 

I used a Motec sensor. 55001: Bosch Water Temp Sensor M12 X 1.5

 

Yes, but the gauge is 0-8V and the ECU will want 0-5 most likely so you'll need to add a 1:2 voltage divided to the lint going to the ecu. I'm trying to recall...the sensor is like 170 Ohm I think, but check it, the go at least 10x higher the voltage divider resistors so you don't mess up the gauge reading. ALso its not linear so you'll need to figure out what reading is what temp, dropping it in a pot on the stove with the thermometer in the pot and meter on the sensors is probably the easiest way if google doesn't deliver numbers.

I installed a modern sensor then use a PWM output from the ECU to run the gauge, you need a calibration table so not all ECUs can do this but it seems to work well.

what ECU are you using?

No-ish. There is very little circulation through the tank so it will be slow responding.....it could probably be used but I don't think that's an ideal solution.

I've used the block as ferripilot noted on the couple 308s I've done as well as my V12 but I use a 12mm GM sensor.

edit, found a link
https://www.bmotorsports.com/shop/product_info.php/products_id/1598

 

M14 is available too, here is the bosch part
https://www.finjector.com/eng/temperature_sensor_m14_x_1_5_bosch_0280130037-p-84797-29

 

Right, the one currently in the block is a temp switch not a sensors....but you no longer need it so its a great place to add the new sensor you do need.

Technically the hottest temp should be at the cross flow manifold, but the water pump is always circulating water through the block even with the thermostat closed so the 2 positions will always be pretty close so it doesn't really matter which goes to the ecu or gauge i don't think.

 

As I said above, I don't think it matters and I've done it both ways.