DaveInNBPT

My 2016 E350 with 36,000 miles has a humming or whining sound similar to what you might hear from an electric motor such as a fuel pump. It is the same at all speeds (independent from wheel or engine speed) but only occurs when car is moving. Not very loud- it may be a normal sound. But I find it bothersome. The sound volume fluctuates a little. When coming to a stop the sound goes away immediately. I am wondering if it is normal to hear a good fuel pump running on these cars? Could the noise be coming from somewhere else? This is a cpo car that I purchased in August. Thanks.

werdn

Maybe diff problem, but your milage is unusually low for diff problems. My 2007 X5 had a whining (more of a ringing noise) from the back, and had to replace the diff this summer. The ringing got louder and louder.

Or might it be from a pulley. Try reving the car when its stationary with the hood up and have someone listen to the sound.

Good luck!

DaveInNBPT

Thanks for your reply. The front differential was replaced in December due to a ringing noise from 70 to 80 mph. After putting in two new ones, both with the same problem, MB factory tech came up and decided to have one custom made in Germany. This one is a little better but I still hear it. Looks like all W212s have this problem because last week I drove another 2016 E at the dealer with 20,000 miles and it had the same ringing problem similar to the”custom made” diff in my car.

I think the new humming noise is different because it is the same pitch at all speeds. That is what made me think of the fuel pump, which in fact may be the problem, but I don’t think I should be hearing it, even in a wagon. I can’t think of any other electric motor-like sound that might be coming from the car. It is not the heater fan or the two fans that cool the LED lights. Problem is, the sound occurs only when the car is moving so I don’t hear it under the hood when the car is idling. Pulleys all sound OK, at idle and when revving. I will take it up to the dealer and have a tech go for a ride with me- hopefully he will hear it (car is still under warranty).

My brother-in-law says I should just go out and buy a Camry. NOT READY FOR THAT YET.

Darel

Definitely your fuel pump, though I'm not sure why it's so noticeable. Mine certainly isn't. Was it replaced with an aftermarket one at some point?

DaveInNBPT

Hi Darel,
I bought the car in August with 33,000 miles from the Manhattan MB dealer and I had them run a check of the service history (the car was bought new there) and there had been no repairs other than routine maintenance. So I think the fuel pump is original. It is loudest at between 30 and 40 mph, but not so loud that indicates an impending failure (at least not yet). Although I am 67, I guess my hearing is still pretty good. I could hear the bad front differential but my wife couldn’t initially. It also wasn’t picked up during the CPO inspection. So I guess I am hypersensitive to noises. My 99 300TD (with 215,000 miles) doesn’t make any similar noises- just the “soothing” hum of the diesel.

I will see what the dealer says.

I worry about the practicality of keeping today’s cars past the warranty. If I find a car I really like, I will keep it a long time. I had an 88 Lincoln Town car for 25 years. Yet I worry that it won’t be practical to do that anymore. The invoice (under warranty) for the differential was over $9,000, but since it took MB 3 tries to find a good one, they must have at least $20,000 into this car so far. (That also means there are a lot of W212s out there with this problem). In addition, while replacing the differential for the second time, they got an error code for the steering rack, which has to be removed as part of the process. So they replaced that also.

I will say that the dealer (Portsmouth NH) and MB have been really great about all this. They also gave me a new MB loaner car to drive each time.

Costi245

Hi. I just wonder of have solved the problem. Mine is making griș noise too.

DaveInNBPT

Hi, I learned that the noise, which I can hear at most speeds, is the high pressure fuel pump, which is located behind the engine, I believe. The noise is considered normal . Not sure if newer models are quieter. It isn’t real loud, and most owners might not notice it.

toledotom

I had the same issue! Front wheel bearing or Axle CV-Joint. I replaced both, left driver's side and it went away! CV-Joint boot is Bad probably, mine had 10 slits in the boot and water or dirt gets in. REPLACE! I did mine myself saved Hundreds.

Paxfobiscum

Bring it back to MB Manhattan and replicate it on the road

DaveInNBPT

Here is some history prior to and not included in original post:
Bought car from Manhattan MB as CPO with 33,000 in August of 2019.. Had it shipped up to MA. On first drive, I noticed a driveline noise primarily at 70 to 75 mph. Took it into dealer up here and the tech could hear it on test drive. Then they put it up on lift and ran it up to 70+. Noise was coming from front differential. They replaced it but did not test to confirm noise was gone. I brought it back after leaving dealer with noise still there. Dealer replaced diff again, this time checking it and finding that noise was still there. Factory tech came in and they looked elsewhere for problem. One wheel bearing was replaced but noise was still there. They then took a differential out of a used car with known good (quiet) differential and put that in and noise was gone. I believe that this diff was a different part number. They then got a rebuilt diff with that number from factory and put it in and they found the noise (at least from the diff) was gone.

Fast forward to original post: Although the diff noise was significantly reduced, it (or another noise) was still there and I concluded that all 4 Matics emit some noise (and that, even at 68 years old, I am obviously hypersensitive to noises). So I wrote the original post. I also decided to take car to another MB dealer and they could not hear any abnormal noises. They did say that the high pressure fuel pump does emit a noise. Car now has 45,000.

Still love the car otherwise—brilliant in-your -face red, real chestnut brown leather, wood and leather steering wheel, great overall ride...
But, with 200,000 + sales of this series (2014 - 2016) am I the only one hearing these noises? Should the factory hire me as a forensic noise specialist?

Paxfobiscum

You dealer in MA is alright as they did all that testing and replacement.

Fliplegend

Part of me whats to hear an audio clip but part of me doesn't. My 2016 has 37K and I have not "noticed" this noise.

DaveInNBPT

High Pressure fuel pump noise is noticeable mostly at lower speeds if at all. Drive on a smooth road at about 30mph and see if you hear it. If not, then don’t worry about it.