I eventually got permission to remove head & check rods etc.The conrods were all straight & there were no broken rings or gasket leakage etc that i could see.I have now got the head back on & run it up again & it is still the same.The compressions are even on all cylinders. When i disconnect the glow plugs the surging/hunting at idle when first started seems to near enough stop. The glow plugs are drawing approx 35 amps constant until they are switched off. I can only guess that the current draw from the glow plugs is effecting the fuel pump quantity adjuster or something. Any suggestions would be helpfull as i suspect the insurance company will turn around & refuse to pay for what has been done already unless it is sorted. It's difficult to catch what is happening because once warmed up after a couple of minutes it seems ok. Kind Regards