SL/R230: Buzz noise while pressing brake pedal BEFORE startup [VIDEO]
Thread Starter
Junior Member
Joined: Apr 2015
Posts: 33
Likes: 2
03' SL55
Buzz noise while pressing brake pedal BEFORE startup [VIDEO]
03' SL55 w/29K. She usually sits on a trickle charger during the week 
Recently started making an odd sound BEFORE startup. After I get into the car and press on the brake pedal this noise is coming from the engine bay [VIDEO] - https://www.dropbox.com/s/09j1o3z5ep...artup.mp4?dl=0
This noise is happening before I even push the Start button on the shifter. Any thoughts? I have not yet been able to determine if this happens before every startup or only after the ones where it's sitting a while.
Recently started making an odd sound BEFORE startup. After I get into the car and press on the brake pedal this noise is coming from the engine bay [VIDEO] - https://www.dropbox.com/s/09j1o3z5ep...artup.mp4?dl=0
This noise is happening before I even push the Start button on the shifter. Any thoughts? I have not yet been able to determine if this happens before every startup or only after the ones where it's sitting a while.
Last edited by sl55per; May 16, 2017 at 03:34 AM.
Thread Starter
Junior Member
Joined: Apr 2015
Posts: 33
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03' SL55
update
Interesting, it just seems so incredibly loud to be normal. It hasn't seemed to affect driveability any and I am not finding any kind of leaks under the hood.
I just noticed something else interesting, after I took her out for a spirited run I pulled into the garage and after I shut the car off the same (Brrrrrrrr) noise came back. So I can verify BEFORE startup and AFTER turning ignition off. Now I need to determine if this is every time or only after she is sitting for a while.
So the consensus so far is that this is normal? I suppose the supercharger pulley squeak is considered normal too so why not right?
(dielectrics grease did fix that)
I just noticed something else interesting, after I took her out for a spirited run I pulled into the garage and after I shut the car off the same (Brrrrrrrr) noise came back. So I can verify BEFORE startup and AFTER turning ignition off. Now I need to determine if this is every time or only after she is sitting for a while.
So the consensus so far is that this is normal? I suppose the supercharger pulley squeak is considered normal too so why not right?
(dielectrics grease did fix that)
MBworld Guru
Joined: Dec 2009
Posts: 10,782
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NO LONGER ACTIVE
Normal. It's the SBC's electric pump pressurizing the system. Mine does it sometime just when opening the door with the engine off. Anytime it registers the pressure below a certain level, the pump will run. It does "go to sleep" after sitting a while, but then anything that sends a CAN bus wakeup signal (unlocking, opening a door, etc.) can cause it to run if it needs to pressurize.
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Joined: Jul 2014
Posts: 158
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From: Your moms house
2015 S63 Coupe C217, 2008 C63(X), 2009 C300(X), 2003 SL55(X) , 2013 S550(X)
Yup its normal, nothing to be worried about, mine does it too. this car has a few sounds that seem abnormal but are normal, after a while you will get a feel for it.
