So I have created a few posts on this forum regarding this issue but I have had no luck in finding the problem.

Currently my car is sorned and I run it every week or so however, after idling for 20 minutes or so, the coolant in the resoviour is right at the top as if the tank is completely full... This is quite concerning since the coolant is almost at minimum level whilst cold... 

In a previous post I pointed out that the cap for the tank is hissing and bubbling around the thread so I bought a new one and the hissing has stopped.

The below video shows the car turned off after running for 20-25 minutes. You can see the boiling coolant right at the top of the tank and a slight hissing sound on the right hand side of the engine.. 

Also note that I only just spotted what looks to be a leak on the right side of the engine (as seen in the video). What is that component? and is that the problem?

Video below:

https://imgur.com/gallery/IjFklBj

What is temp gauge showing and is radiator fan on? 

1 hour ago, CollumPlz said:

after idling for 20 minutes or so, the coolant in the resoviour is right at the top as if the tank is completely full... This is quite concerning since the coolant is almost at minimum level whilst cold

What would be concerning, would be if the level in the EXPANSION tank stayed the same. The idea is when the engine is cold the level is low and when the engine is hot the level is high. I have read throgh your posts and conclude you have an obsession about the cooling system on a car that you don't use.

 

1 minute ago, isetta said:

What is temp gauge showing and is radiator fan on? 

After a few minutes the temp goes to about half way and stays there... the radiator fan does not turn on for some reason (I have heard that could be due to the thermostat..). The fan did come on at 100% as soon as i turned the engine off though..

Just now, unofix said:

What would be concerning, would be if the level in the EXPANSION tank stayed the same. The idea is when the engine is cold the level is low and when the engine is hot the level is high. I have read throgh your posts and conclude you have an obsession about the cooling system on a car that you don't use.

 

This just doesn't seem right too me.. The car will be driven next month so I am making sure it isn't buggered..

That expansion tank is filthy, I'd consider replacing that. I'd also most definitely drain the coolant whilst you're there and give the whole system a good flush out.

The expansion tanks fail over time, they get tiny hairline cracks in them.  I did suggest replacing that in your last thread.  

The thing on the back right isn't part of the cooling system.  That's a brake pressure reducer/regulator.  You might get away with just nipping up the nut.  They are oddly expensive if you need a new one! 😮 Genuine Ford Focus C-Max Fiesta Mk5 Front Brake Pressure Reducing Valve 1469610 | eBay

 

 

1 hour ago, TomsFocus said:

The expansion tanks fail over time, they get tiny hairline cracks in them.  I did suggest replacing that in your last thread.  

The thing on the back right isn't part of the cooling system.  That's a brake pressure reducer/regulator.  You might get away with just nipping up the nut.  They are oddly expensive if you need a new one! 😮 Genuine Ford Focus C-Max Fiesta Mk5 Front Brake Pressure Reducing Valve 1469610 | eBay

 

 

I didn't see your reply on my last post about that tank 🤦‍♂️. My bad, i'll look into replacing that. I just thought that the amount it boils is quite alot so a tiny crack wouldn't be able to do that.. right?

59 minutes ago, CollumPlz said:

I didn't see your reply on my last post about that tank 🤦‍♂️. My bad, i'll look into replacing that. I just thought that the amount it boils is quite alot so a tiny crack wouldn't be able to do that.. right?

It needs to be air tight in order to build & maintain the correct pressure.  Even the smallest crack will stop that being possible.

1 minute ago, TomsFocus said:

It needs to be air tight in order to build & maintain the correct pressure.  Even the smallest crack will stop that being possible.

Okay. Thank you, just ordered a tank 🙂