Bizarrely, just had my 159 in for squeeky rear brakes (service had tightened handbrake too much) and they (alfa specialist near my work) spotted the coolant tank crack. It actually looks like it's been folded, that kind of zig zag pattern and the transparent plastic has gone white. Pretty pink coolant, that's dried on the hose gives it away. Surprised they (alfa dealer near my home, allegedly alfa specialist) didn't pick it up at the service. I think I shall be switching garages
I did have an issue with losing coolant in it's first year, a mysterious loss of coolant with no evidence, mechanics were mystified. Turned out after a lot of pressure testing (and I believe Desira had to get in special equipment) to be a hairline fault in the ali head, so was burning off water in the engine and luckily repaired under warranty thank god.