It is the red plastic screw in the hose to the middle right of the engine bay. It is to bleed air out of the cooling system. Apparently they don't sell the screw as a separate part only with the entire hose. Some aftermarket parts replace the plastic with a brass screw. It is in the lower radiator h...

I forgot to say that it is a 2001 S40 Base model.

My niece is out of town and somehow managed to break the head off of the coolant bleed screw in the lower radiator hose. I need to know what size and what threads that thing is so I can tell her what to buy. Thanks in advance. If I was with her I would fix it in a minute...