noise when starting mainly from cold
 

hi all,

its my first post here and i am hoping to shed some light on this noise. It mainly happens on cold start-ups but it's not consistent and can happen at other times also. Lasts for like 20 seconds or so and it then goes away. seems to come from belts area.. (i hope its not the main chain belt so soon)
Car has 42k miles born in oct 2014 and has only been serviced by MB. under warranty until 2017 December. Noise can be heard better with opened bonnet.If inside the car you cannot hear it.

I took it to my main dealer and apparently they couldn't hear it. I have now recorded it with my phone and send an e-mail to their service manager hopefully waiting to hear from them next week.

Can someone please listen to the attachment and give me your thoughts as to what it might be.

thank you,
kannani

See if you can take a long wooden dowel and CAREFULLY hold the belt tensioner. See if the sound abates. Good luck.