Hey everyone 
 
So this is the water outlet on the 3sgte im pulling apart. The hole that you can see on the bend, appears to me that it has been drilled and tapped from a previous owner. I just want to verify, is it from factory or is this the work of a previous owner? 
 

 
Cheers
 
 
 

Definitely not a standard hole.

Yeah that's exactly what i thought, cheers. I wonder what in hell it was put there for? and is it worth finding a new water outlet or finding a way to close up the hole.

Most likely was just for another sensor.
Would be pretty easy to have it welded up

I would say an aftermarket water temp sensor, or maybe pressure, for a gauge or aftermarket ecu, prob find its 1/8" NPT thread, if you find the thread, you can get a plug for it, use a bit of liquid thread sealant, altho as there not that hard to find i would just buy a new neck

Cheers guys!  In that case i might as well take the opportunity and grab a water temp sensor and gauge since half the work has already been done for me 

Not much thread there as that section is thin, also no flat surface to put a gasket. Ild weld it and if you must there are other more sizable section on the base to thread in a sender

Fair enough. However if the thread has been tapered, along with the use of hydraulic sealant. That should be more than enough to create tight enough seal with out the use of a gasket?

If its just a little water temp or maybe water pressure sensor with a 1/8" npt thread, then it would be tapered, and wont have and cant use a gasket or crush washer ect, it will just try to seal on the tread, so thread sealant is needed. 
Most good water temp sensors, it all the factory 3 on the same neck, or normal aftermarket bosch ones ect have a crush washer.
 
+1 for what MANDALAY said, not much thickness there, i would weld it up, or get new.
 
If you wanted to run another sensor, and still needed the 3 factory, i would weld on a threaded bung to suit what sensor you want to put on. Just take it to any good alloy tig welder, wont cost much, much better then sensor being knocked and coming off, and motor overheat.

Also, be aware that any sender mounted there would be 'post thermostat', meaning that it will only work after the motor has warmed up.