Okay, took me a while to respond back. If you happen to have reverse br-br-br sound you might want to check your rear engine mount. It was not worn but one bolt broke and others where that lose, doing nothing. Now I still can hear something but it is more like 'old car sound' then this loud br-br-br. With hood open and play with throttle it did dod hand still does not make worying sounds. I wasn't able to figure out what the sound is that I now have. Since it is a lot less loud no chance to record it I suppose.
Still, if someone has an idea or a tip how to find out what it might be I am all ears.