High pitch hum after shutdown

[Todd]

After I turn off the engine, a resonating high pitch hum seems to emanate from the front of the engine. Does this represent the biturbos cooling down? After a number of minutes, the sound disappears. :vhmmm:



Mugello Blue RS6
wife's car - '01 Allroad

[smehairbi]

i get the same ..... and i live in the middle east ....... so its very hot and what i learned is that ... this is the sound of the turbos cooling down.........sometimes it reaches to 5 minutes or even more:addict:

[Erik]

Could this be the fan behind the Navi again...?

[half-sick]

Just want to mention that it may be wise to let engine run for a few minutes after hard driving in warm weather. so says the owners' manual, btw.

[nene]

I do hear mine as well. It definitely sounds like a pump of sorts. Does not stay on for long though.

I have found that it comes on occasionally, even if I just drive like an old lady going to church on Sunday.
I don't see it that it comes on more often after spirited driving.

BUT...once I do hear it on, if I am stopped and ready to turn off the car, I just leave it idling, until the pump noise stops. Once it does, I turn the beast off.
I figured since I don't know what it is, it won't kill me to just be cautious anyway!!!

[Bauer]

Could be the after run pump for the turbos. Its a electric pump that keeps pushing coolant through the turbos once the car has been turned off to help cool them so they dont cook (just FYI). Its a good idea to let the car cool down (idle) for several minutes after hard driving. The after run pump will help cool the turbos...however the oil in the turbos will have a greater chance of cooking after hard driving even with the after run pump. It is better to let the car cool the oil and circulate through the turbos instead of sitting there and cooking the bearings.

:rs6kiss:

[TheBrit]

Originally posted by Bauer
Its a good idea to let the car cool down (idle) for several minutes after hard driving.
Even better to do 5 minutes of gentle driving after a hard run IMHO - keeps some airflow though so the cooling is more effective, a hot RS 6 can make a nice warm air patch round itself pretty quickly when standing still.

You should all be doing some gentle driving after a run already - unless you live right out of town, you should be slowing down as you approach home anyway!

[Bauer]

Even better to do 5 minutes of gentle driving after a hard run IMHO - keeps some airflow though so the cooling is more effective, a hot RS 6 can make a nice warm air patch round itself pretty quickly when standing still

Agreed.....I tend to drive slowly through my neighborhood and then pop the hood and let it sit and idle for a few more minutes. Warm up and cool down is probably some of the best preventitive steps you can take to protect the engine. :mech: