MK7 Fiesta 1.0 Ecoboost Expansion tank Leak from Bottom

[JohnyP30]

Hello Ford Fam,
Long time lurker, first time writer,

I've been having a coolant leak from underneath the expansion tank( the circle that i drew) since i changed it a couple of weeks ago.
That little "circle" is supposed to be open or closed with some safety cap on?
Because when the car is running hot, some portion of the antifreeze leaks through that "circle".

Is my expansion tank "broken" and i need a new one?
The antifreeze that i use is motul 50/50 pink, not the oem from ford.

Appreciate it guys!

[ThaiFiesta]

I don’t recall that being open on the new replacement I purchased 🤔

[JohnyP30]

5 hours ago, ThaiFiesta said:

I don’t recall that being open on the new replacement I purchased

Could you a have look on yours if possible?
Or where did you bought your replacement?

[ThaiFiesta]

4 hours ago, JohnyP30 said:

Could you a have look on yours if possible?
Or where did you bought your replacement?

I got it new from Ford. I’ll take it out and look when I get the chance. 

[HornetUK]

I've just been shown the same hole in the picture above and told that's where my coolant is leaking.  How does a hole appear like that in the tank as it looks like a drain hole? Thanks 

[TomsFocus]

23 minutes ago, HornetUK said:

I've just been shown the same hole in the picture above and told that's where my coolant is leaking.  How does a hole appear like that in the tank as it looks like a drain hole? Thanks 

That is a drain hole.  It connects to another hole just underneath the cap seal.  When the cap gets blown open by excess pressure, coolant runs down through that hole rather than spraying all over the engine bay.

If you've got a constant leak there, you probably just need a new cap.