This might be a long post!!!!
As you know all of us have been thinking about the possible fault with the cooling system and to be honest I think the Boy has covered most areas now, so I went back to basics and pictured the engine as a whole not just he cooling system,
then it struck me, the diesel engine has two cooling systems!!!!
The intenal moving parts are cooled by oil then the oil is cooled ny the oil cooler, now part of that oil cooling system is oil squirters or jets directed at he bottom of the pistons to carry away heat, and on one of his first posts about the tracctor he mentioned that after changing the oil before he had even started the engine the oil in the sump was black!! couple this to no service history and my thinking is that the oil squirter and a lot of the other oil ways are possibly blocked ny gunge!!! now if the oilsquirters are blocked the pistons are going to get blooming hot!! and the only place for the heat to be expelled is the water cooling system, as you know the pistons are close to the headgasket which means teh cooling system is trying to remove far more heat than it was designed to do, this is causing hot spots and literally boiling the coolant to steam hence the blowing out of the coolant, it also explains why when ticking over for hours it doesent boil and under normal cruise condition it dont chuck water out, but when undr hard boost and the pistons get to hot the system cannot cope!! but it can cope if he backs off and cruises when it gets to hot!
so your thoughts please guys? am i on the right track or talking 'dangle berries'?
I reckon a very strong oil flush which is only available to the trade would go a long way to helping cure the problem, but it may be that its to far gone to do it that way but its got to help?
Omegatoy