Hello, I have a 2019 W205 C300 4-Matic. When starting the car from a cold start, the car doesn't squeak or squeal until it drops RPMS. After dropping rpms, it will SOMETIMES squeak and squeal. Example being in the first video, it is squeaking and squealing, and in the second video, which is after driving the car from work to home (10 min car ride), it has stopped and is idling at the same rate as it was in the first video. Thank you in advance, and I apologize if it seems like I'm being paranoid or stupid, but I'm just a little confused.

 

First thing I would assume causing the sound at low rpm idling is related to the belt ( A6269930096 ) or the pulley. As it drops RPM the frequency of the noise would be easier to hear.

 

My money is on #1 then #2 in that order.

 

Sounds good, thank you!

 

I will try that. Any video recommendations?

 

Nope, they are VERY easy to access and replace with even the most basic skill set. Just be careful putting the belt back on.

Experianced person....well, it would take me (and has) under 20 minutes start to finish to replace the two pullies. Novice? Hour tops. It is a very easy job. If you have a metric ratchet wrench set you have everything you need.

 

with the belt off, inspect the waterpump shaft. any roughness in rotation, high drag or wobble in that shaft will necessitate pump replacement in the future.