So, my partner and I bought a focus, unfortunately from a private seller! (Won’t be doing that again), within the first day I noticed the coolant was disappearing, lots of inspection, couldn’t find the fault visually, so took it to an engine specialist, turns out the cylinder head was cracked!! Replaced that, and had full engine rebuild, still losing coolant???? 
egr cooler has been taken off and inspected, radiator too, along with thermostat and housing, all pipes checked, no issues with any other components but it’s still losing coolant, the car drives lovely, you wouldn’t even be able to tell there’s anything wrong with it until you look under the bonnet and see the expansion tank is empty! We are getting seriously fed up of blindly throwing money at this car 😢 

we did go back to the seller within 24 hours to ask to return the car and get our money back, he told us to f*** off!!! 

16 minutes ago, Romi said:

we did go back to the seller within 24 hours to ask to return the car and get our money back, he told us to f*** off!!! 

By any chance, is your drivers footwell carpet damp?

No, completely dry, I did question heater matrix but that’s been checked too 

Hi Romi,

Q1: Does the coolant dissapear when the engine is not running?

Q2: How long does it take for it to go from Max marker to Min marker?

Q3: is Oil clean?

Q4: Or it is leaking inside one of the cylinders aven after the engine rebuild? You don't mention any smoke coming out the exhaust, but maybe not enough is getting in the cylinder to generate visibile smoke?

I am asking about how long it takes because I once had an issue like this and the coolant was in fact dripping only while the coolant was cold and there was some pressure in the system. It wasn't  dripping too much so the footwell carpet never got damp, and it took a couple of weeks or a bit more for the level to drop from max to min. But in your case since the heater was already checked I imagine it is not the issue, but maybe there is another point in the cooling system which looks good when investigating but it drips in certain conditions?!

 

Hi, thanks for your reply. 
no the coolant doesn’t drop when cold or even when the car is just idling, it’s only dropping when you actually drive and the car gets up to temp. 
within 5 miles of driving the expansion tank is completely empty. 
there is no smoke or steam coming out of the exhaust, have replaced the head as original was cracked in more than one place, head gasket and all belts replaced as standard with an engine rebuild. 
no wet or damp in the footwells, I’m literally stumped. It’s back at the garage that did the work, but they’re all scratching their heads too. 

Radiator been checked, egr cooler, thermostat and housing. Expansion cap and tank changed, all pipes checked and getting hot. Heater matrix checked, water pump checked, whole system has been drained, flushed and refilled. Still same issue.  And yes the oil is clean as just been serviced too 

So, up to temp means the thermostat is open and the full cooling circuit is used. Driving means the engine is reved so maybe there is an increase of pressure? For sure there is an increase in coolant flow. Therefore, if cold and reved engine results in no coolant loss, it means that the coolant is not leaking inside the engine, nor inside the car. I can now only think of somewhere in the extended cooling circuit which is used when the thermostat opens. To loose the volume of an expansion tank in 5 miles means there is a serious leak somewhere so maybe it is visibile with engine up to temp and reved?

 

Once I saw a car which was blowing the coolant from its expansion tank only when the engine was hot and the revs went up close to the red line. It turned out it was a damaged head gasked and exhaust gases were getting in the cooling circuit pressurizing it until the expansion tank cap opened its pressure valve and coolat was thrown out. Of course it was visible that the coolant was everywhere outside the expansion tank and all over the bonnet and engine.

Which engine is it?

15 minutes ago, TomsFocus said:

Which engine is it?

1.6tdi duratorque 

Not a complicated cooling system on those (unlike 1.0 EcoBoost).  I reckon it's just not been bled properly.  Or there's a pinhole on the radiator that can't be seen with a visual check.

I would suggest getting a coolant pressure tester.  Place it on the reservoir and pump it up to around 20psi then leave it overnight.  That should force any water out of the weakest point under the highest pressure that the cap would allow.  If the pressure doesn't drop overnight, it's likely to just be an airlock.  Would recommend having it professionally vacuum bled in that case.

So the mechanic seems to have found the issue, where the water goes into the block on the back of the engine, there are plastic grommets inside the holes and they are damaged, that is where the water has been leaking from!