Whirring noise from engine

[Deleted117900]

Good Morning All,

Not much of a poster of sorts but looking for a bit of advice.

Car Details:
Mercedes C180 Coupe Kompressor - Engine: M271

Fault:
I've noticed a whirring noise from the engine which has only showed up the last week. The best way to explain it is that is sounds like a computer whirring noise and will go with the revs as I apply pressure on the throttle.

I'm pointing to a possible alternator issue but would prefer it to be just the pulley. I done a bit of serching around on the web and I have used the console on the dash to read the voltage and all seems to be good. I'm not having no battery issues or any warning lights on the dash at present.

The best video I have found on youtube to compare the noise is this - https://www.youtube.com/watch?v=rTVrnkW_uRk I have the haynes manual and I'm willing to replace this by myself.

Using a VIN decoder I have found the part number to be 'A2711540802' and looking on Ebay I am seeing a few used ones. Any advice on what you would do, what would you replace being cost affective? I would say it was the alternator but could it be the pulley bearings?

ECP want a silly amount for a new alternator and do we have any other sites that sell MB parts or refurbish the alternators?

Thanks.

 

[Trickythemerc]

Could be the belt tensioner or idler pulley bearing. Simple test is to drop the poly belt off and run the engine,if the noise has gone then check the pulleys etc for bearing noise or play.

 

[Deleted117900]

Thank you!

I will update this post as I go! Recently just changed the brake discs and pads and changing the air,oil and fuel filter with an oil change with Mobil 1.