t5 1.9 tdi Buzz/humm when turning off engine

[Richierich]

just curious, does anyone know what the humming/buzz is after you shut off the 1.9 tdi engine?

[Umai Naa!!]

It's the vacuum system pressurising back to atmospheric.

Nothing to stress about. They all do it.

[jfoldbar]

It's the vacuum system pressurising back to atmospheric.

Nothing to stress about. They all do it.

i drove a few 1.9s that never done this.



Richierich. in a 2.5, the n75 valve, perhaps called boost pressure regulator.(correct me if im wrong) can make the noise you describe. im not sure if the 1.9s have them but i guess they would.

[Transporter]

As Umai Naa! said, nothing to stress about. You can trust him, he is VW Audi tech.

[Umai Naa!!]

Cheers, Miro.

Mine does it all the time if it's been run longer than 10 minutes or so.

[Richierich]

Cheers. I looked today, vacuum makes sense, its a little motor up the top hooked up on the same line as the brake booster. (A vacuum pump?) btw how do you get manifold vacuum in a turbo engine? ive never thought about that before..

[Umai Naa!!]

On a turbo petrol motor, it's no different.

On a diesel, both turbo and not, you need a vacuum pump.

[greymad]

just curious, does anyone know what the humming/buzz is after you shut off the 1.9 tdi engine?

That sounds very similar to a noise on our T5/132kw which not only does it on occasions after shutting down, but also intermittently while on the road. It's VERY annoying, and if a prospective new car buyer was to experience it during a test drive, there'd be a "no sale", I guarantee.

[Umai Naa!!]

In your case it'll be the electric water pump and the oil pump in the DSG, after shutdown.

[greymad]

In your case it'll be the electric water pump and the oil pump in the DSG, after shutdown.

I very much doubt that to be the case: I'm taking a punt on its being the N75 valve and am getting that changed out ... I will report back as to the outcome (and cost!)