[AlpinWeiss2k18]

Hello!

I own a BMW E90 2009 320d 177hp with stage 1, not xdrive and a manual gearbox. At the moment the car has 152k km. In December, on a road outside the city, I got tired of a small whistle in sixth gear. I played with the speeds a bit and I saw that in the third and fourth gears it was doing the same (only in acceleration). Only in the fifth gear did he not do it. I replaced the gearbox before Christmas with a second-hand one. After replacing it, I didn't notice the sounds. Yesterday I heard the same sounds again, but much louder in the third gear than in the fourth and sixth gear. Nothing can be heard in the fifth gear. In the old box I had changed the oil a few months before it broke, and in this one I filled it with 100ml. With this gearbox I did about 4000km . It's not the same sound as a broken turbo / intercooler hose.It is a thin whistle combined with a sound like a wheel bearing. The differential on the back is ok, the cardan shaft has no vibrations and both rubber cardan flanges are replaced few months ago by new OEM parts. The clutch is ok, it doesn't make any noise when I step on the pedal or ’’in the cold in the morning’’. The weekly is about 80-100 km in the city and 250-300 outside the city. I don't know what else to do with them. Maybe there's something wrong with the car. I think that if I put another one, it won't do the same in two or three months. I didn't find anyone with a problem like mine anywhere on the internet. Or was I lucky enough to break it in two months? 
Any help is welcome!