2012 Outlander 650 (Gen 1). There's a plastic piece that sits on top of the head (also on top of the thermostat), I have no idea what it's called, but the coolant flows through it into the head.
Recently I had a severe coolant leak so we stripped the bike down and found that this plastic piece had a small hole in it. I've ordered a new piece, but it's not arriving until after a planned ride.
Two things.
1. What is this plastic piece called? I forgot to ask the dealership when I described it to them.
2. Is there any way to temporarily plug this hole so I can ride on Tuesday? It needs to be something that can withstand the temperature and pressure of the coolant.
That is your "thermostat housing". If the hole is small and accessible, do you have room to drill & tap it? Then screw in a fine thread bolt with sealant on the threads.