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      07-29-2021, 11:33 PM   #1
chrisc151
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Engine fan after shutdown??

Ok,can someone tell me why the G05 50i engine fan stays on for like 5 minutes after driving for a short or long time and shutting the engine off? I'm coming from a F15 50i where the fan stops after the engine stops...

Thanks and search wasn't my friend on this topic...
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      07-30-2021, 06:40 PM   #2
Frenetic
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It’s normal.

The coolant pump is designed to operate after car shut off to prevent oil coking in the turbos.

These engines run exceedingly hot and are prone to oil coking if a very hot engine is immediately shutoff. In fact it’s recommended to let the car cool down sometimes after spirited driving by letting it idle for a few minutes before turning off the ignition. It allows the oil to dump heat.

The fans running after engine shutoff attempts to achieve the same thing, albeit it’s not as effective.
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      07-31-2021, 03:28 PM   #3
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Quote:
Originally Posted by Frenetic View Post
It’s normal.

The coolant pump is designed to operate after car shut off to prevent oil coking in the turbos.

These engines run exceedingly hot and are prone to oil coking if a very hot engine is immediately shutoff. In fact it’s recommended to let the car cool down sometimes after spirited driving by letting it idle for a few minutes before turning off the ignition. It allows the oil to dump heat.

The fans running after engine shutoff attempts to achieve the same thing, albeit it’s not as effective.

I don't think anything is being coked at engine temps...you need like 600C for that to happen.
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      07-31-2021, 07:27 PM   #4
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Turbochargers can get up to 1,000 degrees Celsius. It’s exposed to exhaust gases and PV=NRT.

Hence, why it’s recommended to let engines idle after spirited driving and why the coolant pump operates after engine shutoff.

https://www.sae.org/publications/tec.../2015-01-2029/

Last edited by Frenetic; 07-31-2021 at 08:19 PM..
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      08-02-2021, 06:47 PM   #5
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Water cooled turbos aren't as prone to coking of the oil, but without that circulating and the coolant, too, you can get way hotter than you want...so, the cooling system can keep running, depending on the temperature. The ambient temperature makes that much more of an issue when it's a hot summer day versus a frigid winter one and after a harder run at speed versus cruising.
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