M279 "whirring" noise?
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MBWorld Fanatic!
Joined: Jun 2009
Posts: 3,040
Likes: 125
From: Atlanta Metro
Current: C217 V12TT AMG Previously: C55 AMG, SL65 AMG
M279 "whirring" noise?
Hello folks,
Trying to figure out what this "whirring" noise is from my C217 M279. I can describe it as:
1) It sounds like an electronic version of a wastegate, that's struggling to open or close
2) It only happens during deceleration or when coming to a stop
3) Of course, I can't replicate it on my driveway when in Park, so I can't hop out to stick my head under the hood and find it
4) Revving in park doesn't make it come back; it appears it needs to happen when in drive and under certain conditions (which I can't seem to replicate)
5) You can faintly hear it from the driver's seat as a "whirrrrr" for a few seconds. Or perhaps more accurately as an "errrrrrrr" sound. It's not the sound of a bad pulley bearing (I had those on the C55)
6) There's no codes and the car appears to drive normally, albeit a little sluggish due to the V12 programming (but nothing new there). It still pulls like no other when you really get on it.
At first, I thought it was maybe a suspension or brake related component (MBC or ABS) but that seems to be working just fine and doesn't make a noise during all braking and/or when raising or lowering the vehicle.
Side note: Every so often, I also have this strange issue on takeoff from a stop - when accelerating with about 1/3 to 1/2 throttle, the throttle becomes extremely jerky like if I'm on and off the gas every half second. It makes the car lunge/lurch up and down. I need to completely get off the throttle and let it come to vacuum before I can get back on the throttle and drive normally. I'm not sure if this is related to the whirring sound, but thought I'd post about it too.
Trying to figure out what this "whirring" noise is from my C217 M279. I can describe it as:
1) It sounds like an electronic version of a wastegate, that's struggling to open or close
2) It only happens during deceleration or when coming to a stop
3) Of course, I can't replicate it on my driveway when in Park, so I can't hop out to stick my head under the hood and find it
4) Revving in park doesn't make it come back; it appears it needs to happen when in drive and under certain conditions (which I can't seem to replicate)
5) You can faintly hear it from the driver's seat as a "whirrrrr" for a few seconds. Or perhaps more accurately as an "errrrrrrr" sound. It's not the sound of a bad pulley bearing (I had those on the C55)
6) There's no codes and the car appears to drive normally, albeit a little sluggish due to the V12 programming (but nothing new there). It still pulls like no other when you really get on it.
At first, I thought it was maybe a suspension or brake related component (MBC or ABS) but that seems to be working just fine and doesn't make a noise during all braking and/or when raising or lowering the vehicle.
Side note: Every so often, I also have this strange issue on takeoff from a stop - when accelerating with about 1/3 to 1/2 throttle, the throttle becomes extremely jerky like if I'm on and off the gas every half second. It makes the car lunge/lurch up and down. I need to completely get off the throttle and let it come to vacuum before I can get back on the throttle and drive normally. I'm not sure if this is related to the whirring sound, but thought I'd post about it too.
Last edited by Viper98912; Mar 19, 2025 at 02:30 PM.
Senior Member
Joined: Jul 2007
Posts: 283
Likes: 102
From: Maryland
S 550, S65 Coupe
I think I may have the same issue. Only hear it while in gear and at idle after coming to a stop. Once I touch the gas it goes away, put it in park it goes away. It sounds like cavitation so I was thinking maybe it could be the power steering pump but doesn’t make sense that it makes the noise not under load. Hopefully someone will chime in with some info.
MBWorld Fanatic!
Joined: Feb 2012
Posts: 2,608
Likes: 1,208
From: Phoenix
222 S-65
Electric power steering in a 222 says not a power steering pump noise.
If you listen closely you can hear MBC calling for pressure from the pump, and it saying “I’m good” when it has enough.
A keen ear will pick up on A/C calling for more effort from the variable displacement compressor.
These things get easier to pick out as the car ages.
If you listen closely you can hear MBC calling for pressure from the pump, and it saying “I’m good” when it has enough.
A keen ear will pick up on A/C calling for more effort from the variable displacement compressor.
These things get easier to pick out as the car ages.
