Hi all, i have had this noise in my car for about 1 month, thought it was the pulley tensioner (belt) changed it and the problem still persist. Anyone had this before. Car is w205 220 bluetec 2014 (270k km)

 

do you have any CEL’s or codes? I would start there. If you don’t have any diagnosis equipment like an Autel to confirm parameters.

that sounds like an exhaust leak or something having to do with the EGR. Could also be the glow plugs or something with the injectors. It’s tough to diagnose those kinds of issues through a screen or remotely.

 

Sounds like one of the pulleys is fixing to leave your stranded...

Remove belt tension to inspect freeplay:

• check the wobbly idlers pulleys
• check the water pump bearings
• check A/C compressor bearings
• check the steering pump if any
• check the alternator pulley

It is odd you have replaced the tensioner and not the idlers and belt...