Its been 2 and a half years since I posted here with this same issue, I've taken it to a few mechanics and none of them can identify the issue. Thankfully, its not a head gasket issue, if it was, the car wouldn't be operating now. 

There is constant air in the coolant system, I have several times done the trick where you rev the car at above 2000 for a few minutes, sometimes up to 4000 for a few seconds with the cap open and the problem returns. I always open the coolant cap on the right hand side of the engine and this lets whatever air out. I have replaced the tank 3 times due to me cracking the old ones by letting air out when its overheating (bad idea I know)

I am constantly having to put coolant in and that stuff isn't cheap, it can do long journeys as long as there is coolant before I set off. I also notice a high pitch noise coming from the left hand side of the engine, this noise happens after I turn the engine off and it doesn't stop until I open the bonnet and leave it for a minute it seems. I have attached a YT video of the noise and the area. 

When I've topped it up with coolant, when the engine gets to its desired heat, the temp gauge drops by 30 degrees ish and then goes back up, it only does this a once or twice before chilling at its desired temp. I'm out of ideas and hope, this is the last year with the car before its paid off and hopefully I can get a new one.

I've also attached images of the area where the noise is and also what car it is (just a stock image)

I beg someone has a solution for this.

 

Why do you say it's not a headgasket issue?  There's no specific timescale for a failing gasket to last.  Has a sniff test been done to rule it out?

That whine is perfectly normal, it's just the throttle body self test.

 

6 hours ago, TomsFocus said:

Why do you say it's not a headgasket issue?  There's no specific timescale for a failing gasket to last.  Has a sniff test been done to rule it out?

That whine is perfectly normal, it's just the throttle body self test.

 

Massively appreciate the reply!

I haven't done a sniff test no, will look into buying one though. However, we've had 2 full services and there has never been any issue with the oil, its never been a milky colour and the people servicing it said there isnt an issue there. 

I also have never experienced power loss/acceleration or maintaining speed. The car still runs at full capability engine wise thankfully.

 

Good to know that noise is normal because its been driving me insane, whats the reason for it self testing everytime its powered on and off?

Seems to be a common misconception that oil will always be involved in a headgasket failure.  Most I've seen have failed between the cylinder and the waterways so just pressurises the coolant.

Various components self test every time the ignition is switched on or off.  A cynic could suggest it's designed to wear out parts more quickly.  I'm sure Ford would tell you it's to make sure the engine runs at optimum every time...

4 hours ago, LiamF said:

whats the reason for it self testing everytime its powered on and off?

For things that open and close to varying degrees during normal operation it is not unusual for them to go through a fully open and close cycle at switch off to make sure there is nothing obstructing them and often quickly several times to shake off any crud as well.