spent a few hours this morning trying to the to the bottom of this,
removed the top rad hose and repaired the bleed nipple housing, flushed the coolant system, refilled and bled twice.
Let it run to see what the temp was doing and re-bled again - temp was rising slowly, as normal. But as soon as it got to the 1/3 mark the temp rose quicker and past the fan cut in point. Checked the coolant hoses for heat and they were warm, but not as hot as I would expect nor were they solid.
So I removed the expansion tank lid and I could hear the pressure escaping but then the water level rose within the tank almost coming out the top before settling down again
....... bugger!
So is this pretty much pointing to h/g failure?