Hopefully i can help..
What engine size do you have exactly?
Its a standard 2.5 diesel engine.
Hi..thanks for your reply..
Ok..From i recall if you look at the left hand side of the engine or left hand side of the water pump housing..you see the housing held with about 2 bolts obviously you will have the larger coolant house going to it..the thermostat will be within there..i can give a diagram below to help..
However im not to sure this would be the cause for the increase pressure you describe..Usually any increase in pressure within the coolant system aswell as bubbles in the expansion tank would suggest headgasket failure..this means the exhaust gases/cylinder compression is getting into the coolant system and this causes the increase pressure to cause things like coolant being forced out the tank/blow a coolant hose or blow the radiator..one way to verify that would be to aquire a dye test kit/chemical block test for exhaust gases leaking into the system for headgasket failure if the dye changes colour then you'll know for sure what the fault is..of course if the headgasket has gone then the head will need to be inspected for heat damage aswell as the coolant system itself that may have contributed to the headgasket going in the first place..so as above maybe try the backfush and the dye test and see if that narrows it down.certainly from what you say with the increased pressure buidling in the tank would suggest the gasket has gone unless the system itself hasnt been fully bled properly in which something else to certainly ensure has been done...I do hope this helps.if you need to ask anything else or include anything further then just continue before you rate
I was thinking similarly....Thanks for the advice...