Knocking noise
Thread Starter
Newbie
Joined: Jun 2024
Posts: 3
Likes: 2
S-class
Knocking noise
I have a knocking noise coming from the engine area of my S-class. It only occurs occasionally after driving - not every time the car is taken out. The local Mercedes dealership has not been able to diagnose the problem. I am hoping that maybe someone in this forum has dealt with a similar issue and may know the cause. I have added a video giving an example of the noise.
Thank you
Thank you
MBWorld Fanatic!
Joined: Aug 2007
Posts: 1,885
Likes: 815
From: Pacific Northwest
2001 S600 V12 Sold, 2011 Jaguar XFR Sold, 2017 S550 4-Matic, 2018 S63 AMG Sedan
Yes, definitely open the hood and remove the engine covers. See if you see anything. If I had to make a shadetree mechanic guess I'd say it's the clutch on your Ac unit. BUT..major caveat: That is what it would have been in the old school systems if you were low on refrigerant. The refrigerant also serves as a lubricant. So if the refrigerand was low, or the system hadn't been used in a long time, you would hear that little noise. I have no idea if that appolies to these cars or not, so I'm not even calling it a guess.
Thread Starter
Newbie
Joined: Jun 2024
Posts: 3
Likes: 2
S-class
Thank you very much for your response. I took the car back to Mercedes when I heard the noise again. And asked if they had checked the items you mentioned. They finally fixed the problem by replacing the tensioner. I appreciate the help.
Debbie
Debbie
