Ouch
Guess your lucky your temp is OK

exp tank seperated at seam
ut why does the hose look like it also has been exposed to severe pressure
or is also a weak walled defective part?

I did notice the 140 on thr radiator cap
is that the 1.4 bar

I have been trying to get a new cap myself
for my 83 500 SEC but my cap has 120 on it

I'm searching for specs on the rating of radiator cap for my car
My cap seems ok but car seems to run hot
NowI think it could be a faulty electrical connection or temp guage
Still a new radiator cap can't hurt
but I still need to confirm the pressure

Good Luck