om617 coolant sensor thread size

[chrisgt]

I'm looking the thread size of either the coolant switch for the EGR (which is disconnected) or the sensor for turning on the aux fan on my 84 300td. My aux fan doesn't come on, it isn't the sensor but the logic on that fan is faulty in my mind, anyway. I want to put in a different sensor hooked to a microcontroller for a smarter control of the aux fan and also for a digital reading of the actual coolant temp.