2011 mondeo 2.0 tdci coolant system pressurising at running temperature

[milacy]

2011...mondeo 2.0 tdci... coolant system pressurising up at running temperature.... had new thermostat housing and cambelt and water pump ( water pump impeller ok)..... no leaks... no oil in water and no water in oil... engine runs at 90° ( dont over heat) ... fan kicks in to cool system.... leave the expansion cap off and coolant systems ok...as soon as fit expansion cap and get to running temperature the system pressurise up and all coolant pipes go hard...and starts passing coolant pass the expansion cap.... any ideas would be appreciated thanks

[nicam49]

Hi, has this happened since you changed the pump, etc? 

[unofix]

The system is meant to be under pressure about 13lb when hot that is why you should never remove the filler cap when the engine is still hot. If the expansion tank is too full it will blow off the excess coolant.

When the system is cold the expansion tank should only be about half full. Also is the system filled with 50% Ford coolant and 50% water?

[milacy]

9 hours ago, nicam49 said:

Hi, has this happened since you changed the pump, etc? 

No.... ive only change the pump and cambelt belt due to the pump having a plastic impeller