Humming after engine shutdown.

[Krazydragon780]

So when I got to the store, I shut down the motor, removed the key completely, and sat there and relaxed. Then I noticed that there was this gentle hum coming from between the firewall and the AC. This lasted for a good 5-10 minutes perhaps and then stopped. Does anyone know what this is? Is this normal? Am I crazy? Please chime in.

[n8vs3]

I noticed the same thing in my S3 and I think it is normal.

[AnthonyA3]

Ya mine does it also, pretty sure it's normal.

[KevinM.]

If I had to guess, its probably a fan to cool something down.
Very normal, i hear it too

[bakedcorn]

If I'm not mistaken, its the oil pump still circulating oil to allow the turbo to cool down.

[Krazydragon780]

If I'm not mistaken, its the oil pump still circulating oil to allow the turbo to cool down.

I have also heard this somewhere else. Is there any way to confirm this? I think that's a great innovation of Audi if this is truly what the noise is. It certainly deters oil from cooking on the turbo parts, and causing premature wear.

[forbiddenbeat]

If I'm not mistaken, its the oil pump still circulating oil to allow the turbo to cool down.

Just reminded me of the days when I ran a turbo timer on my B5 S4. :D

[Krazydragon780]

Just reminded me of the days when I ran a turbo timer on my B5 S4. :D

Krazydragon780 likes this

[HurrayFive]

The, "huuWAANT... huuWAANT... huuWAANT...", noise that you hear several times immediately after shut off is oil recirc through the turbo center cartridge as the remaining oil pressure bleeds off. Once the engine is off there is no oil pressure beyond that.

The high pitched, "hRRMMMMM", humming that persists a while after is coolant recirc through the turbo center cartridge. Both designed to help keep the turbo bearings in better shape after hard driving. At least that's according to the last tech I asked about it, seems about right.

They've had similar tech since the last generation EA888, and most new DI turbo engines have similar features now. The old car guy in me still let's the car idle for a couple mins after hard driving so oil can circulate over the bearings. Noise is totally normal though.

[KevinM.]

Awesome, I glad to know that I'm wrong because this seems like a great feature to help prevent some kinds of wear which may have been more prevelent in older turbocharged engines.

[Blaine]

If I'm not mistaken, its the oil pump still circulating oil to allow the turbo to cool down.

^ Old cars required you to install a turbo timer to ensure your turbo cooled down properly. Now the manufactures caught up with COMMON sense on how to keep the turbos from melting.

[duncanator]

Yeah, my A3 hums for a bit, but also have some regular electronic pulse sound coming from the engine. My wife said it sounds like a bomb timer and that my car is just counting down the days where it will explode and kill us all. Very weird car...when it's off.