Thanks to all for your replies.
Very helpful as always on this forum.
I've the day free tomorrow so will give all the suggestions for the cause a look at. But will order a new bowl/ expansion tank as a matter of course.
Artic.. Am I right that the Y piece sit between the starter and the oil filter housing? Is it a major job?
Thanks again all.
Gary.
Who would think a few cracks would upset the system
Wasn't me. It was Arctic2.Nodge
Thanks for posting your info.