Its the fuel pump priming, my vw does this too.

 

Alright, I know I've been making cracks about the Hyper Drive and was ready to throw some stuff out to the group about the Flux Capacitor but it can't logically be the fuel pump.

As already stated, the fuel pump is in the gas tank and would clearly be audible from outside the vehicle. Additionally, why would the fuel pump/system not be fully pressurized at the time the ignition is turned off? Obviously, the amount of fuel and fuel pressure required at the time of ignition is much lower than required during normal driving (much less spirited driving). Also, these cars use very little fuel on a per second basis so even a low volume pump would be able to meet the requirements of the vehicle in the matter of a partial second.

It's got to be the steering wheel lock...servo or solenoid.

Wow, never thought this would get this serious!

 

The sound I hear IS audible from outside the car. Furthermore I can hear it from both the rear (near the fuel tank) and the front. So it could be the fuel pump. I can also hear the sound inside the car. T-Horn, the fact that it doesn't do it EVERYTIME, only after a long period of inactivity is puzzling me. Why would the steering wheel lock only sometimes?

Also, some of the noises after you switch the car off are due to the turbo. Our little turbo gets hot, and it needs to cool properly, so after turning the car off a fan runs. Even after the fan is done there is a longer hum. I think this may be continuing to pump lubricant through the turbo as a common problem with turbos is that once the car is switched off, the oil stumps circulated, so the stuff in the hot turbo gets even hotter and basically bakes in there and clogs stuff up. So that's my theory for noises after the engine is off.

 

I don't know for sure but.......it could be a pneumatic locking system.
I have had other cars, specifically mid-90's VWs, that had a pneumatic locking system that made a VERY similar noise when locking and un-locking.
There are little vacuum lines that actuate the plungers for the locks. They are a serious PITA when you have to replace the door =)

 

i always thought it was my mini gasping excitedly at the chance to motor... :-) kinda like i do everytime i walk outside...

 

I can hear it 20' away if there isn't any background noise. I too think it's the fuel pump.

 

Could it be the fuel filler door.

 

It's possible, but why does it make the sound only after long periods of inactivity? The fuel door locks everytime you lock the car. Plus the hum is too long to be just a simple lock.

 

Because it isn't the door, it is the pump.

If you have NAV, that drive will also spin up when the door is unlocked.

 

Guys,

It's the fuel pump, no doubt about it. Any solenoids for doors, windows, steering, etc would make a short, muffled clicking sound.

This is definately the sound of an electric motor spooling. Because the MINI uses direct fuel injection, the fuel system runs at substantially higher pressures than a normal fuel injection system. As mentionned before, to avoid delays in the startup sequence, the computer primes the system when a door is unlocked or whatever.