P38 Bmw diesel overheating

Overheat last weekend, I have drained and flushed system out no blockages no oil in water and no water in oil. It seams to be air locked I took it for a run today to heat up, expansion tank filled up and water coming out of expansion tank overflow, water in tank cold, I am thinking thermostat is staying closed. If i take bleed hose off boiling water and air comes out.

Any ideas please

Thanks

mine did exactly same....was told it was airlocked....but wasnt given a cure....i reckon thermostat...hope you get it sorted..check between rad and intercooler for debris....i needed a new motor in the end.....even the new one overheated within an hour...thrashed it to hell and it aint done it no more....

I think the head gasket is gone on mine, prob between a cylinder and water jacket, as its pressurising.
You said you needed new engine what was wrong with your engine

I would go for the water pump first they only have a plastic impeller had quite a few go Check the tempreture at the bottom of the rad if its cold then its allmost 100% water pump

Oh well found out whats wrong
head gasket pressurising system so heater matrix and radiator bot gone bill is at 2k already