Coolant system leak

bmax

 Put the boat in today (finally) and found a leak on the port engine (rh side looking from front on a Volvo Penta 5.7L  2011) there is a angle fitting coming from the side of the block under the exhaust manifold that has what seems to be a sensor (temp??) attached to it, it has a serious leak with the engine running but stops when the motor shuts down. Any ideas what that part is?? At the bottom of the 90' corner is where the leak seems to be, almost seems like it should have a drain plug in it but there was never one there.

bmax