Citroen CX Coolant Bottle

[awajiboy]

I have a Citroen CX 2.5 DTR Turbo Diesel 2, please excuse my ignorance, but what is the purpose of the RED plug in the coolant bottle(see Picture). Mine seems to sweat a bit but no big coolant loss. Is it there as a pressure relief if the coolant system becomes over pressured. I await your knowlegable answer. Steven
download/file.php?mode=view&id=67147

[aerodynamica]

Hi there, I could not view your photo but if I recall from my CX days, the cooling system expansion header tank had a red item fixed to the side with an extension inwards to the tank. I could be wrong by I think this is simply a visual indicator for the correct coolant level when cold. I think the coolant is supposed to be at the level of the red thing.

[awajiboy]

Thank you for your reply.