Why does my Ford Ecoboost make a strange noise when I turn off the engine?

I have a Ford Focus 1.0 Ecoboost 2017 model. When I switch off a noise like a fan running on comes from the front top of engine. This is not the cooling fan. Is this normal or does it need attention?

Asked on 29 October 2018 by Paul atkinson

Answered by Honest John
If you switch the engine off immediately on stopping, after a long ascent, after constant speed on the motorway or after driving fast then a pump will continue to circulate coolant through the extremely hot turbo as it cools down and the heat may be sufficient for the thermo switch to switch on the fan. It is best to idle the engine for a minute in these circumstances before switching off as that also circulates the engine oil through the turbo making it less likely to carbonise and block the turbo oil feed and oil return pipes.
Similar questions
I am looking at a Mercedes-Benz Vito 114 but the air intake of the turbo seems rather noisy. The sales guy says this is normal and the van drives well. Is this sucking noise normal?
When warm and idling, I can hear a whining noise from the engine of my 2014 petrol Ford Kuga 1.6 2WD. This happens with or without clutch depressed. It disappears at other revs.
When my neighbour fires up his Porsche, it sounds as though an explosion has taken place. Is this noise standard or can it be 'tweaked' in some way? Is there a legal limit to the noise that cars can produce?
Related models
Relaxed but still enjoyable to drive, well-equipped for the money, a huge choice on the used market.
 

Ask Honest John

Value my car