I recently had the coolant  recall done in the motor 1.6 ecoboost 2011.

A few days later driving on motorway liw coolant warning came on.got to work and checked level, it was just below minimum. Got sone water and removed cap and a load if air bubbled out and the coolant level increased to maximnum level.

This happens every week or so, low coolant alarm, when i check its jyst below minimum, when i loosen cap a lot of air hisses out and coolant level goes back to maximum level.

This isnt normal is it???

Starting to worry about this now, just been looking at engine whilst at running temp, i had my daughter rev the engine and big bubbles of air coming through the large hose in bottom of expansion tank.

Is the head gasket toast?

It just Sounds like Air in the Tank   so once the water gets Hot  ,the air in the tank will push water out of the " overflow pipe" hence you keep topping it up 

one fix it to remove the cap on the bottle and run the engine  till all the air bubbles stop,  if they dont  then you may have a leak   or drawing in air from somewhere, i take it there is no fluid under the car ?

Ran it with cap off for ten mins.

Now coolant level on minimum level, but after running around town today took cap off and no pressure at all ( after it had cooled down)

Should there be a flow through the expansion tank when engine running?

Looking at it nothings flowing, just a dribble through the tiny top hose into tank.

That's the de-gas hose which I assume is intended to bleed off any air or vapour that's accumulated at the top of the cooling circuit. As far as I understand it in modern cars there is a flow of coolant through the tank, hence the two larger pipes.

Personally I've never quite understood the thinking behind this. When remote expansion tanks were first introduced they definitely didn't have a flow throught them, only having one pipe from the top of the radiator. My understanding was that having the tank remote from the engine meant it stayed cooler and eliminated loss by evaporation. Before that the expansion space was at the top of the rad and when hot this space would be filled with vapour that would then be lost when the pressure cap vented leading to a gradual loss of coolant.

With the current arrangement the coolant in the tank is hot so I would have expected to get loss by evaporation again, but then I'm only an old f@rt so what do I know?

The cooling system is a fully closed system. during operation the cooling system becomes pressurized because of the expansion of the coolant. The pressurisation  of the coolant increases the boiling point of the coolant. The boiling point of the pink/orange coolant that Ford uses in a pressurized cooling system is approximately 135 degrees Celsius. 

The spring operated pressure relief valve inside the coolant reservoir cap does not open during normal operation. The pressure relief valve is only intended to open in situations where the coolant system (as a result of a problem) builds up an excessive amount of pressure. The pressure relief valve prevents the cooling system from damage in these situations. During normal operation the pressure in the cooling system is much lower than the pressure that is needed to open the pressure relief valve.

Any vaporised coolant inside the cooling system will not leave the system. Being a fully closed system the vaporised coolant condensates inside the coolant reservoir.

The only point where (a very small amount of) coolant is allowed to leave the cooling system is the waterpump. The waterpump of the 1.6 TI-VCT, 1.0 ECOboost and 1.6 ECOboost has a mechanical seal that is cooled and lubricated by the coolant. Especially when these water pump are new and the seals are not bedded in yet these waterpumps can loose quite a bit of coolant. After the seals are fully bedded in the amount of coolant that leaves the system from the mechanical seal is hardly noticeable. 

7 minutes ago, JW1982 said:

The only point where (a very small amount of) coolant is allowed to leave the cooling system is the waterpump. The waterpump of the 1.6 TI-VCT, 1.0 ECOboost and 1.6 ECOboost has a mechanical seal that is cooled and lubricated by the coolant. Especially when these water pump are new and the seals are not bedded in yet these waterpumps can loose quite a bit of coolant. After the seals are fully bedded in the amount of coolant that leaves the system from the mechanical seal is hardly noticeable. 

One of my previous cars, a SAAB if I remember correctly, had a little catch tray cast in just under the water pump seal to catch the coolant drips. The liquid evaporated quicker than the leakage so nothing reached the floor.

ScaniaPBman

Allow me to give my recent experience. I have a 2012 Galaxy 1.6 Ecoboost. At about 100,000 miles it started losing water at about 2 litres every 300 miles. Engine malfunction warning each time. The head gasket had been  replaced at about 65000 miles.  2 garages (including Ford main dealer)  have been unable to find the cause of the present problem.  I assume they would know about this issue but did not mention it. Iwas advised to top up with coolant when needed. That;'s about £4 every week or two. The timing belt will need replacing at 125k so I wonder if they will find the water pump leaking them? 

On a 10 year old vehicle that's got over 100,000 miles on the clock and no obvious signs of a leak I would just be using a product like 'Radweld' and that will most probably fix the issue in a few days.