[TurboniumD]

Sometimes when I turn off my 2001 NB I get a weird hum that lasts for 20 seconds or so. This has been going on for some years now. Yesterday it was several times louder than usual.

The only thing I have been doing differently is running the car to 4K RPM oon most take-offs... i read somewhere that this is helpful for keeping intake clean.

Does anyone else share this hum symptom?

 

[Growler]

could be your radiator cooling fans running... especially if you were running hard before the shutdown.

 

[jpdeuce]

When it's humming have you gotten out of the car to hear where it's coming from? Have you popped the hood to see if you can tell where it's coming from? I would assume the same thing that it's the fans, but it's not terribly warm in many parts of the country to have a heat problem. I'm in Texas and I do not have a temperature problem with mine, nor do the fans run after engine shut off.

I think you need to find out where it's coming from.

 

[hannaco]

If you had a 1,8T, that would be an easy answer. But for the TDI a bit more difficult. The hum, is it like the sound from the radio when the station goes off the air? Or, like an electric motor cranking up a window?

 

[TurboniumD]

like a radio

 

[snoopy indy]

It's probably the anti-shudder valve that is resetting itself.

The anti-shutter valve is what actually kills the airflow to your car, therefore allowing the engine to shut down. Once the engine has "died", the valve reopens and is ready to allow air back in when the time comes to restart the engine.

It does sound kinda weird at first but you get used to it.

Diesel on!

 

[hannaco]

You might give the inlet area of the EGR valve a cleaning. If oil builds up there, the anti-shudder flap can stick. On the back side of the EGR is a small lever that you can gently push to move the flap.

 

[TurboniumD]

Thanks for the anti-shutter info. I'll check that out.