WHen replacing the serpentine belt I broke this little black rubber hose (1/4" or 5/16" I guess) that connects a plastic port (below the ignition coils) to something below the cooling water reservatory. I was able to reconnect that little hose, but its rubber is just very deteriorated by age, so I think to replace it with a plastic (vinyl) hose.
What it is used for? Can I use a plastic one?