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Low pitched humming noise from the engine while driving.

Old Apr 25, 2023 | 09:40 AM
  #1  
drgeorgeroy's Avatar
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From: Trivandrum, Kerala , India
Mercedes Benz E250 CDI ( W212 facelift)
Low pitched humming noise from the engine while driving.

Hi guys,

I own a used 2013 facelift e250. Since the past few days, i noticed that while driving up a steep hill, at around 1500-2500 rpm there is a low pitched humming noise coming from the engine.
I haven’t recieved any warnings in the MID , nor is there any difference in performance.
This noise isn’t as audible when i revv the engine in park mode.
My mechanic had a look at it. He has a suspicion that it might be from some rotary component in the alternator and less likely to be from the turbo since its low pitched.

any other possibilities that you guys might have come across? I haven’t had any major issues with my car so far and this is really worrying me. Any input will help.
Cheers.

Last edited by drgeorgeroy; Apr 25, 2023 at 09:44 AM.
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Old Apr 25, 2023 | 01:25 PM
  #2  
CaliBenzDriver's Avatar
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W212 MY'14 M276-3.5NA @75kMi
This and that

Originally Posted by drgeorgeroy
Hi guys,

I own a used 2013 facelift e250. Since the past few days, i noticed that while driving up a steep hill, at around 1500-2500 rpm there is a low pitched humming noise coming from the engine.
I haven’t recieved any warnings in the MID , nor is there any difference in performance.
This noise isn’t as audible when i revv the engine in park mode.
My mechanic had a look at it. He has a suspicion that it might be from some rotary component in the alternator and less likely to be from the turbo since its low pitched.

any other possibilities that you guys might have come across? I haven’t had any major issues with my car so far and this is really worrying me. Any input will help.
Cheers.
How about your Transmission oil service ...?

How many odometer Miles ?

Serpentine belt, tensioner and plastic idlers are always on their way out. Replace together as a kit (see dealer or FCP Euro)

Do you have an handheld fault scanner... get one! (Autel, iCarsoft)
🤞
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Old Apr 26, 2023 | 06:27 AM
  #3  
drgeorgeroy's Avatar
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From: Trivandrum, Kerala , India
Mercedes Benz E250 CDI ( W212 facelift)
Originally Posted by CaliBenzDriver
How about your Transmission oil service ...?

How many odometer Miles ?

Serpentine belt, tensioner and plastic idlers are always on their way out. Replace together as a kit (see dealer or FCP Euro)

Do you have an handheld fault scanner... get one! (Autel, iCarsoft)
🤞
my mechanic had scanned the car. There is no obvious fault codes related to this issue.
my car has done around 40,300 miles.

Im not sure whether the previous owner had done transmission oil service. I got the car 8 months ago and I haven’t done it yet.
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Old Apr 26, 2023 | 02:33 PM
  #4  
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W212 MY'14 M276-3.5NA @75kMi
low mileage maintenance

Your MB specialist should have no problem telling you what is producing that noise. Across the world through Internet without a sound sample, it's a bit more challenging. Could be a wheel bearing too...


Go ahead and apply the scheduled maintenance and a "multi-point inspection".
Once could argue that fluids need to be replaced based on time or mileage (coolant, differential, ATF).
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Old Apr 27, 2023 | 03:30 PM
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2010 E550, 273 Engine: 2012 S550, 278 Engine
Originally Posted by drgeorgeroy
Hi guys,

I own a used 2013 facelift e250. Since the past few days, i noticed that while driving up a steep hill, at around 1500-2500 rpm there is a low pitched humming noise coming from the engine.
I haven’t recieved any warnings in the MID , nor is there any difference in performance.
This noise isn’t as audible when i revv the engine in park mode.
My mechanic had a look at it. He has a suspicion that it might be from some rotary component in the alternator and less likely to be from the turbo since its low pitched.

any other possibilities that you guys might have come across? I haven’t had any major issues with my car so far and this is really worrying me. Any input will help.
Cheers.
It could be your electric radiator fan picking up speed when you put extra load on the engine going up steep hills. The fan spins fast but it makes rather low pitch noise.
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Old Feb 2, 2024 | 11:01 AM
  #6  
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From: Trivandrum, Kerala , India
Mercedes Benz E250 CDI ( W212 facelift)
Hi everyone. Forgot to post the update. It turned out to be caused by a vibrating screw of the intake pipe!
I was scared that it could be something major. Anyway that’s over for now.😅
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