So i need some insight. I have a 07 335i that recently developed a thumping/tapping noise from the motor that correlates with the rpms. The noise is loudest between 2-4k rpm with a steady increase. If i throttle to much it isn't there. What the hell could it be? I don't know how to completely describe the sound and every time I try to record it my loud ass exhaust keeps the camera from hearing the thumping. It kinda sounds like if you have a flat and it thumps, but it comes from the motor for sure and its a quick thumping that increases speed with rpm increase (doesn't have to be under load or in in gear). If that makes any sense.. I have no idea what it can be, and want some ideas to see if i can get help diagnosing and possibly diy to save money on mechanics.
Thanks ahead of time!