PD-TDI Engine Noise When Shutting Off

Guest Free account, no CAN development support

Hello everyone,

'Who is familiar with the following phenomenon:'
When I turn off the engine of my AJM (Bora), I hear a noise coming from the engine compartment after about 1-2 seconds. It sounds like a compression release, a dull 'thud.'
Ist das normal oder nicht? Ich habe den Wagen seit 2 Wochen, das Geräusch war von Anfang an da. Sonst ist motorseitig alles normal bis unauffällig. Das Geräusch kommt irgendwie aus Richtung Motorblock, evtl. dahinter (von vorn gesehen). Es hört sich nicht 'kaputt' an, wenn ihr wisst was ich meine. Es ist reproduzierbar und scheint irgendein Ventil o.ä. zu sein, das 2 sec nach Abschaltung irgendeinen Betriebsdruck ablässt. WeiDoes anyone have any advice?
PS: Sorry for my layman's description

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Translated on 03-10-2026, 6:20.

GerTDi wrote:

When I turn off the engine of my AJM (Bora), I hear a noise coming from the engine compartment after about 1-2 seconds. It sounds like a (de-)compression, a dull "WUPP".
Is that normal or not?

.... is perfectly normal. That noise is from the bypass valve. It reduces the braking force so that the engine shuts down more smoothly.
To get a more detailed description of that part, you could try using the search function.

Guest Free account, no CAN development support

'Thank you. I had already searched for 'motor' and 'noise' but couldn't find anything suitable. I'll do some more research now.'

Translated on 03-10-2026, 6:22.

Hi,

Open the valve and take a look, especially when someone else is shutting off the engine. With an ASV (Automatic Shut-off Valve), you can observe this beautifully because the lever mechanism of the shut-off valve is clearly visible.

Best regards,

Jan.

Translated on 03-10-2026, 6:23.

GerTDi wrote:

Thank you. I had already searched for "motor" and "noise" but couldn't find anything suitable. I'll do some more research now.

Hi,

That's fine.
Your description was accurate and very helpful, and you shouldn't feel embarrassed about it. As far as I remember, no one has asked that question before, so you wouldn't have found a good answer even with the search function (at least if you weren't familiar with the term "Abstellklappe").