12 hours ago, Bomb Jack said:

Just a quick update.

I've had it in to a local mechanic twice in the last 4-5 weeks. He's had it on pressure test both days, for over an hour. Had it on the ramp, visually inspecting for signs of a leak, and checked the heater matrix, and can't find a one. 

It's losing around 300-400ml every couple of weeks. 

It's certainly puzzling....

An hour is nowhere near long enough for such a small leak.  Needs to be done overnight at minimum.

Chances are it's only leaking when hot as well, which will make it even more difficult to locate.

If the system is not leaking under pressure test conditions, the only part not accounted for would be the expansion tank cap.

1 minute ago, anon said:

If the system is not leaking under pressure test conditions, the only part not accounted for would be the expansion tank cap.

If that werr the case, wouldn't the cap and surrounding area be wet?

On 10/27/2025 at 8:37 PM, Bomb Jack said:

wouldn't the cap and surrounding area be wet?

No.

The usual problem with a coolant leak with a 1.0 Ecoboost that can't be found is an internal crack in the integrated inlet manifold.

You could do a simple hydrocarbon test of the coolant to see if there are any exhaust gases present. Kits available from Amazon for about £18

Your engine is very likely fubar.

On 5/26/2023 at 7:28 PM, RayC333 said:

So, it irked me that my prep for leaks didn't find a crack or other problem before I re-fitted the cylinder head. Out of interest I thought I'd try and find out why.

I found that the static water leak test I previously dreamed up was and is far too slow to notice a leak into a much larger coolant passage volume. I can now see a slight drop in water volume after waiting 24hrs but even then it's not as conclusive as I would like.

Using bits and pieces from around my home I have now rigged up a better test, albeit still Heath Robinson. Nevertheless, take a look at the pics and video I've just taken with a bit of mains water pressure.

Took a while to decide whether to post here or in Have  a Laugh 😁

 

Well it's due an annual service in early  December. So I've booked it in with my local Ford dealer for a 9 year service, Cam Belt/Water Pump replacement, and told them I also have a small coolant leak.

Is it worth replacing the cap anyway, before it goes in?

2 hours ago, Bomb Jack said:

So I've booked it in with my local Ford dealer for a 9 year service, Cam Belt/Water Pump replacement,

Have you been given a price for this work ?

My guess would be £2395

1 hour ago, unofix said:

Have you been given a price for this work ?

My guess would be £2395

Not exactly, but they said the Cam Belt/Water Pump is around £1,800, so you're probably around the mark inc service and leak.

26 minutes ago, Bomb Jack said:

Cam Belt/Water Pump is around £1,800

That's only double what an independent garage would charge for the same job 🤣

I do hope they will be replacing the oil pump or at least removing and checking the oil strainer.

After checking the coolant level last week, I noticed there seemed to be around an inch of something that was floating on the top of the coolant. You know like oil would separate with water?

But it was a light beige colour. Today I got a pipette, to empty the expansion tank. I then rinsed it out the best I could, but haven't re-filled it yet. The inside top of the expansion tank was also covered in a type of beige cream/foam.

It's booked in for early December, so I may ask them to also replace the expansion tank if it won't come clean when they flush the system/replace the coolant. 

Your engine is toast. If not head gasket then cracked head. Sorry for you.

On 10/27/2025 at 9:53 PM, unofix said:

The usual problem with a coolant leak with a 1.0 Ecoboost that can't be found is an internal crack in the integrated inlet manifold.

You could do a simple hydrocarbon test of the coolant to see if there are any exhaust gases present. Kits available from Amazon for about £18

Nothing further to add to what I have already said.

So is it worth buying a Hydrocarbon Test Kit now?

Or shall I book it into Ford's next week for them to do an inspection?

 

 

Not now no, definitely a head gasket or cracked block causing milky to build up in coolant tank, take the oil filler cap off it's probably in there now as well possibly 

So are we talking a new engine?

Or is that the worst case scenario?

18 minutes ago, Bomb Jack said:

So are we talking a new engine?

Yes !

So don't waste your money on changing the wet belts or getting it serviced, or in fact doing anything to it.

https://pumaspeed.co.uk/product-Brand-New-Ford-Service-10-EcoBoost-Engine_18898.jsp

How much would it be at a Ford dealer to supply and fit?

 

1 minute ago, Bomb Jack said:

How much would it be at a Ford dealer to supply and fit?

Ford dealer charge approximately £8970 to supply and fit new 1.0 Ecoboost engine.

PumaSpeed also offer a fully reconditioned 1.0 Ecoboost supplied and fitted for £2671.30 (inc. VAT)

https://pumaspeed.co.uk/product-Reconditioned-Ford-10-EcoBoost-Engine_21240.jsp

So there's no chance it could just need a new cylinder head gasket, rather than it being a cracked head?

How does the head crack? I bought it when it was 2.1/2 years old, and it has a full ford service history. 

As it happens, my local mechanic can't look at it until after Christmas.

I've booked it into Ford, for an inspection in a couple of weeks.

So that my battery isn't flat when I come to start it up on the morning of it going in, is there something I could do to make sure the battery isn't flat?

After researching on Google it will cause more engine damage to drive it, so I guess even starting it up on the drive isn't recommended?

Would it be worth disconnecting one of the battery terminals maybe?

 

 

Yeah disconnect the battery terminal will stop it going flat, but don't forget the doors won't lock etc with remote

If the battery is original it'll probably be flat by xmas even if you disconnect it.  Would be better off leaving it connected and using a battery charger on it every couple of weeks.

Worth noting that your insurance could be invalid if you disconnect the battery and someone breaks in without the alarm going off.

Thanks for the feedback. I replaced the battery in 2022 or 2023. I've decided to risk it not starting on the morning. I can always jump start it with another car. 

Going back to the coolant leak, I've just found this on Google.

Could one of these issues be my problem?

• Coolant leaks: A common issue is leaks from the thermostat housing or the Degas hose on 1.0 EcoBoost models, which can cause serious engine damage if not addressed.

12 hours ago, Bomb Jack said:

Thanks for the feedback. I replaced the battery in 2022 or 2023. I've decided to risk it not starting on the morning. I can always jump start it with another car. 

Going back to the coolant leak, I've just found this on Google.

Could one of these issues be my problem?

• Coolant leaks: A common issue is leaks from the thermostat housing or the Degas hose on 1.0 EcoBoost models, which can cause serious engine damage if not addressed.

The degas hose was changed completely on the facelift Focus in early 2015.  That won't be the fault here.  (Although as I type this, I'm not sure whether this car is a Focus or a Fiesta?)

Thermostat housing is still common, but you can see those leak at the top end of the engine.