???? valve / knob / turny thing ????

[R11X VW]

HI all.

This is my first post regarding my (wife's) first T25. Got a few questions to ask. I (my wife) have a 1983 1.9 wbx and I'm currently checking to ensure all the fuel lines / water pipes etc are OK. Looking into the engine bay there are 2 water pipes (one on top of the other) and on the top one there's like a little screw/knob/valve. Anybody enlighten me as to what it does before I turn it and the engine falls out the bottom??
Spent a few hours reading through some of the posts on her and already solved some of my issues. Anyhow, all / any help greatly received.

Rich

[kevtherev]

It's an air bleed valve for when you do your coolant changes every two years



should it break they are £44 to replace

[DevonAid]

Every TWO years??

Oops....