Flyingchange

Hi all. I'd appreciate some help figuring out if this sound is indicative of a problem, or just part of the car's normal noises.

About the car/sound:
- Bought the car ('04 CL55) a few months ago. No ABC issues or sagging; all original parts (AFAIK)
- It only happens when starting the car after it sits for ~24h (or longer) e.g. no sound, after the first time, if I start/stop the car throughout the day
- My guess is ABC-related given the whine / high pitch
- It always lasts just over a minute, is loudest near the front passenger wheel, and 'winds down' quite noticeably, then you can only hear the engine humming
- In the recording, at 0:33 I held my phone near the driver's side where it's less intense, and it 'winds down' at 1:12

Thanks in advance!

MartinWake

I can't tell what that is but my car does not do that so maybe just take it to a benz tech for them to check it out.

JRAZ305

i too get it - seems like the dampner on the pump!

Flyingchange

Yeah agreed, that's where my research is starting to point me. On mine the pulsation dampener is separate from the pump though.

JRAZ305

The cylinder extending out of the pump

Flyingchange

Got an answer - it's the secondary air pump.