What is this part! It leaks coolant like a sieve! (2004 base)

[Beelzy]

Ok, epilogue to this project.....
Sourced valve locally at foreign car shop for $40. (Always check local first, saved me$)
Removal required the tube to be undone at cooler, and I removed one clamp, and took the rubber tube, valve, and metal tube out as one unit. A lot of working blind, and limited room. Do not attempt this front the top of the engine, you'll break tubing.