Dear all,
I was back from work tonight and suddenly a loud clanking noise started from the left rear tyre , I stopped immediately and had a look to see if I was as if pulling a metal can or something under the tyre but there was nothing !
I move the car slowly in reversed and still heard it. I touch the break disc and the metal bit behind it and the was nothing , so i slowly proceeded an there was no further sound ...all clear.Please advice .What is this ? Shall I take it to the garage regardless ?

 

Sounds like you picked up road debris - certainly have the MB dealer look underneath the car for any hidden damage..

 

That's the classic noise of a rock caught between your rotor and rain shield. Normally causes no damage, but can be alarming. Reversing direction is the usual way to try to dislodge it short of removing the wheel.