I was wondering what the hissing/buzzing noise is that seems to come from the turbo in an All4 after the engine is off. It can easily stay on 5-10 min after the engine is off. Oil cooler motor? Sounds not fully a hiss, nor fully a buzz.

 

there is a water pump which is cooling down the turbo.

 

Ditto on the electric water pump cooling the turbo.

 

Kind of figured as much, but seemed odd to be running for that long after the shutoff. Thanks for the info!