Ford fiesta st coolant tank discolouration

[Gas1883]

Has any one have any idea on the discolouration of the coolant tank , as if the coolant is expanding to the top of the tank , the car runs fine , temp fine , but I have noticed white smoke from exhaust on occasion, but I put that down to condensation as she only does very short runs , 2 miles to work & back , town motoring .

[Gas1883]

I’m comparing it with my 56k focus 1.0 , her fiesta st is 20k miles , mine looks as I’d expect , her coolant tank discolouration looks wrong to me
Thanks

[Gas1883]

Has anyone got a pic of there mk7 fiesta st coolant tank to compare ? Thanks

[Gas1883]

fiesta_STage3 said:

it’s getting dark now - i’ll take one in the morning for you if no one else has by then.

Thankyou

[Gas1883]

fiesta_STage3 said:

here’s mine mate, it’s a 2017 mk7.5 ST - but, note, it’s a relatively new tank, as they’re a known weak point to go brittle & crack….

Thankyou , looks like there is something going on with the wife’s , though I did look on eBay & the 2 nd hand tanks did look like hers

[Gas1883]

Thanks all , car has just done a 200 mile journey ( I took it instead of my car to see if I could see a issue ) , not using water , ran fine , so it must be the tanks just discolour