The coolant in my Ford Fiesta was bubbling - is this normal for a turbo engine?

I have recently purchased a new Ford Fiesta (not the very latest model) with a 1.0-litre Ecoboost engine. After returning from a drive around town today, I lifted the bonnet and noticed that the water in the coolant reservoir was bubbling. The fan was running. As soon as the fan stopped the bubbling stopped. Water temperature gauge showed normal and not at all raised. I haven't had a turbo engine before and wondered if this was normal.

Asked on 30 August 2017 by Dave 68

Answered by Honest John
The turbo is watercooled and, because turbos run at exhaust gas temperatures, the coolant gets superheated before it passes from the turbo via the degas pipe directly to the expansion tank. If you have driven a long distance, or just driven uphill, best to idle the engine for a minute before switching off.
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Sharper look for the updated Fiesta. Comes with Ford's award winning 1.0 EcoBoost three-cylinder.
 

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