[Hywel S Wales]

Got back from a 30 min local run today and thought I could hear a very low buzzing coming from under the bonnet (No - not atrapped bee!) Anyway I then saw the coolant was bubbling in the expansion tank. After a few more seconds the buzzing noise stopped and the bubbling stopped immediately. Strange ??


I gave the car another shortish run later and kept a close eye on the temp. gauge (normal) and checked again after parking up. This time I left the engine running while I popped the bonnet. All looked o.k. Stopped the engine and the coolant bubbled for about 20 seconds before stopping. No buzzing this time though !


Anybody else noticed this ? Can't be normal surely ? While driving along all is fine, not sure if I need to take to my local dealer to check it over. Car is 16 months old so plenty of warranty if any work needs doing.


P.S the electric cooling fan did not kick in , sometimes it does sometimes it doesn't. Coolant level also looks fine.

 

[Hywel S Wales]

Had another look at it today. I think it's just the coolant flowing back into the expansion tank. As long as engine temperature is normal that's the main thing really.

 

[Nick]

It is the auxiliary electric pump cooling the turbine - on my car it runs 10 minutes after i turn off the engine.

 

[Hywel S Wales]

Thanks Nick.

 

[JimmyH^_^]

Hi guys,I've recently just noticed this today after a 10min drive to MickeyD's and back..
Our's was last serviced in August 2016..since then it has been up and down the land and driven quite hard..


I wonder if I should just bring forward its service as its due it first ever MOT in Septembe this year.


But this bubbling coolant thing is bugging me and worried its doing some damage


Car on 17k on a 64-plate

 

[pegleg]

It is the auxiliary electric pump cooling the turbine - on my car it runs 10 minutes after i turn off the engine.

Which auxiliary pump are you referring to? I've only had the cooling/air conn condenser fan stay on for a few secs after switching engine off.
Never had anything elserun after switch off.
Unless it's so quiet I've not noticed it.

 

[Nick]

1.0 Ecoboost engine have 2 water pumps - one standard, belt driven as in any other car, and one electric designed speciffically for cooling the turbine. It is pretty quiet, so you probably wouldn't hear it unless in totally quiet place, like private garage. When you stop the car and turn off the engine, open the hood and check the expansion vessel - you will see cooling fluid circulating, and probably hear the slight hum from the pump. It is nothing to worry about, just slightly annoying (at least for me
It has nothing to do with cooling fan.

 

[pegleg]

Thanks for that

So there is no need to run the engine at idle for a few seconds aftershall we say, some spirited driving.

 

[Nick]

I don't know about that - i am not an expert in this field, just sharing my experience with the car.
And, while coolant is circulating after the engine is switched off, oil circulation will stop imidiately, so maybe few seconds of idle may still be advisable, at least untill turbine stop spinning.

 

[Willow]

Hi all


I have exactly the same thing. Bubbling (well looks like boiling to me) in the coolant tank. Does not do it all the time though. Is this normal? Never in my experience with all the cars I have owned have I ever seen anything like it. It's under warranty, should I book it in?

 

[Willow]

Having taken my car to a Ford dealer for a different issue, I was reassured by the mechanic that bubbling in the expansion tank is perfectly normal in Ecoboost engines.

It would be interesting to hear of anyone else who has experienced this somewhat alarming phenomenon.

 

[cianpars]

Ive read quite a bit about this willow and it does seem to be normal. On a normal engine, i woyld suspect a head gasket, but so many people with ecoboosts have noticed it with no other symproms, it seems completely normal.

 

[Willow]

Thanks Cianpars.
I would be interested to read where you have been reading this info, it may just go so way to stop me being quite so concerned.

 

[cianpars]

Cant remember now, but im sure ive read a coyple of threads on this forum and the fiesta and focus forums i look at from time to time.

 

[Hywel S Wales]

See this - https://www.youtube.com/watch?v=Y5CcIxVkbiY

or this - http://www.fordownersclub.com/forums/topic/48613-ford-fiesta-10-ecoboost-125-zetec-s-bubbling-noise-help/

Google "Ford Ecoboost coolant bubbling" for more.