Hopefully i can help..
How long does it take roughly to actually register its overheating?
Any unusual smoke from the tail pipe since this fault occured?
Do you still get heat inside the vehicle from the heater/blowers?
Any significant coolant loss or increased pressure in the reservoir?
Can you supply last 7 digits of vin number?
It is still at the garage but I have just spoken to them and hopefully this helps:
It takes about 10 mins from cold to over heat when being reved at 2000 rpm and obviously longer when idle
No unusual smoke
Heat is on and off from heater/blowers which is why they beleive it is an air lock
There is increased pressure
Vin number last 7 digits - BM38220
I look forward to hearing from you
Hi..there thanks for your responce..
I do know these can be pretty difficult to bleed at some points..im not sure wither they tried this or not as you dont say..but when ever we had them in in the past we filled them up up the car up at the front jacked up slightly..so the radiator at the front is at the highest point..and can help get the air out the matrix..of course the heater has to be a fully hot setting..before you bleed the system via the bleed screw...I would imagine givin all what you have replaced so far..they have checked for possible headgasket issues..if as you say you get an increase in pressure in the system you want to see wither this isnt being cause by a faulty headgasket and allowing exhaust gas to filter into the coolant system and cause an increase in pressure building up in the circuit..a proper combustion leak detector kit for head gasket leak detection should verify that or not..have they inspected for a partically blocked radiator,back flushing can help but they maybe able to check that using a digital infra red thermometer...I do hope this helps..if you need to ask anything else or include anything further then just continue before you rate