I recently purchased a new Fiesta ( not very latest model ) with a petrol ecoboost 1.0.  100 engine.

After a drive round town yesterday I lifted the bonnet and noticed that the coolant in the reservoir was bubbling after I had switched the engine off. This continued for a minute or so and the fan was also running. When the fan stopped the bubbling also stopped.

The coolant level when cold is normal and the temperature gauge also shows normal when running.

Is this normal in an ecoboost engine.

Hi Dave

I have a 1.0 Ecoboost Fiesta also, the coolant isn't actually bubbling, it sounds like maybe the water pump or some other pump, pumping hot coolant back to the reservoir to allow the engine to cool. It's done it on mine since new so I wouldn't worry. 

Hi Daniel

thanks for your reply and explanation. Much relieved.

I suspected that it possibly was normal because the temperature gauge showed normal.

 Very pleased with the engine performance. I 

Edited August 28, 20178 yr by Dave68
Spelling mistake

there is an additional electric coolant pump that pumps coolant around the turbo and back to reservoir .this is probably what your seeing with ign off. will run for a short while if sensors detect high temps.

Hello Ian

You have explained perfectly what I was experiencing.

When I switch off after a run the main fan by the radiator switches off a few moments after engine dies. But then you can hear a fainter hum that goes on for a bit longer. When it stops the bubbling also stops.

Your explanation fits perfectly.

Thank you.

On 28/08/2017 at 2:35 PM, iantt said:

there is an additional electric coolant pump that pumps coolant around the turbo and back to reservoir .this is probably what your seeing with ign off. will run for a short while if sensors detect high temps.

Haven't noticed this, just that these things run incredibly hot, and more worryingly what happens if this pump, or any hoses fail. 

21 hours ago, Wiggy! said:

Haven't noticed this, just that these things run incredibly hot, and more worryingly what happens if this pump, or any hoses fail. 

What happens when the hoses fail is well documented - there was a recall on one which split under heat.

Cloud of white smoke and many, many people cooked their engines. 

I have a 2016 1 litre ecoboost 123bhp fiesta. When driving I found hot air coming through the vents. ( the heat was not on) I pulled over to find the coolant boiling. I have brought it to a mechanic who changed the water pump and a thermostat and told me the issue was resolved. I drove the car to work the next day approximately a 45 minute commute. I opened the hood to find the coolant bubbling again. The temperature gauge in the car shows the car isn’t overheating. Any advice on this

Is it boiling or is it just coolant circulating through the system?

The coolant is circulating. And the temperature gauge on the dash isn’t showing that the car is overheating 

hi my 2014 1.0 123 fiesta is doing the same thing (not sure if it should be doing it or not) however my fan doesn't run when on idle or when the engine is turned off after a drive, but you can hear a hum as if it is trying to spin. My main concern is the coolant bubbling / boiling and everything being so hot even though the temp gauge on dash says its fine. does anyone have any advice?

 

thanks!  

 

 

1 minute ago, Mshipley said:

but you can hear a hum as if it is trying to spin

That is the auxiliary electric water pump, which continues to circulate the coolant when you switch off the engine.

3 minutes ago, Mshipley said:

My main concern is the coolant bubbling / boiling and everything being so hot even though the temp gauge on dash says its fine.

The gauge says its fine, because it is fine.

but shouldn't the fan still be running ?

It's 30c+ here at the moment.  If it's the same there, I would expect the fan to be running, irrespective of the auxiliary coolant pump.

Does the fan run when you switch AC on?

You can (carefully!) poke the fan with a stick when it's humming just in case it's stuck from lack of use or dodgy windings.

 

Thanks for the reply

I haven't tested to see if the fan works with air con on yet. I will try that next. Today I put a 12v feed to the fan and it worked fine so the fan is ok. However I removed the fan resistor and it was quite rusty so I will replace that first as its only £15.