I just found the Fiat Coupe Group on Facebook (Thanks Greg/coveryourcar) and there was an interesting comment:
i found the problem it was a split water hose you got any spare?
When mine went I went with the old one to persley scrap yard and found one from another car that was much the same,Now here is a wee trick 4u 2 know,a 28mm copper straight pipe joint fits perfect to join two hoses together wd a jub clip at ether end,Od is almost d same as d Id of org hose!!
I am guessing he means the CHOD?
Facebook group