Hi all, I drive a 325i E90 series and when the car is idling and I open the bonnet I here a noise at the back of the engine. It sounds like hydraulic lifters but when I took the car in to bmw mafiking(north west) they told me it is a small motor that is making that sound and it is because it is a 6 cylinder and it is in all the 325i series bmw's. I would just like to find out, if that is true or not. Thanks and enjoy the day.