Snoring in the engine compartment…

Hello, for some time now I have noticed a snoring noise in the engine compartment. Detailed description and circumstances: – starting from quite exactly 2,000/min and going up to approx. 3,500/min – it snores while accelerating and in sliding mode – sounds most likely like the vibration of a metal part – is no longer heard with a warm engine – sound source seems to be right (in driving direction) I have already wobbled at various parts in the engine compartment, at least spon The Schnarr base: 99-er 9-3 LPT / 154PS / ca. 125.000km Before I hit the way into the forge, which is certainly advisable: Do any of you know this noise? Thank you and say hello, maywald