VW Mk3 Jetta, Passat TDI and other/older diesels
This sound only occurs when the car is started for the first time. And only when it is cold outside. It also emits some white smoke. After a couple of seconds, everything is fine again.
Passat b6, 2006, 2l 103kw
https://youtube.com/shorts/KI7zgVOjmMM?feature=share