Just bought a 1998 225 Explorer and there is a screw on cover to a fill port of some sort. It looks original but I’ve no idea what it is. If you look from the underside and inside the transom, there’s no hose connected.
It’s not the raw water system, that works fine and it’s not the fresh water shower system either - that also works. The water fill port is port side anyway.
Can anyone help identify it for me?
