Eddie Schwartz

Recently bought a new 2017 GLC 300.
Love the car, wonderful piece of machinery.

Right after driving off the lot, we noticed a whining sound coming from the rear when cornering.
Took it into MB service. They were very attentive and agreed the sound was not normal.
After servicing ... this was the story as per the service department

Humming noise coming from rear differential. Found one document about humming noises in drive train when cornering.
TIPS #GI35.31-P-066283. Warm up oil in rear differential, drain oil in Diff. Fill up differential with SPECIAL OIL as per tips document.
Road test, no more noise noticed.

Thoughts?

guhvies

Have you noticed the noise again? If you haven't, then it is fixed for now...

Eddie Schwartz

I believe the factory may have put in the wrong oil into the differential. Hence, they had to put in SPECIAL oil at the dealer ...
Hypoid Gear Oil is specifically made for differentials.

Kwheeler

I own a 2017 GLC 300. A month or 2 into owning it less than a year ago I started noticing a whining noise coming from under the car. Over the last few months it has gotten louder and louder.a I begin suspecting that during the certification somebody put the wrong oil in, or drained the oil from the Differential and never replaced it.
I learned that when driving and cornering. if the noise changes gettting louder or shifts to one side of the vehicle you have wheel hub issues. usually the outer bearing. If the whining noise comes from underneath the dashboard or right underneath the Cup holders in the front seats. that is a transmission problem. If the noise seems to be coming from the underneath the vehicle towards center or rear that is the rear differential. In my case .it is a rare differential issue. I bought my car with an extended warranty on it and I do believe it is covered and being replaced right now hopefully. My experience with this noise is that I went out on a quiet country road and sped up to about 65. then Listened to the noise as the vehicle slowed down. I noticed as the gears in the transmission shifted the noise did not change tone it just lowered in tone as the vehicle slowed. This told me it was a gear issue not a transmission issue. The noise would gain in pitch and volume as I went faster and then lower in pitch and volume as I went slower. at 1st I thought it was the brand new tires being very noisy. I hope this information helped you.

seamus2154

Wow, we had the EXACT same scenario. I did think I had something to do with it. We bought a 2018 GLC300 Certified. Love the truck. I alway baseline a new car in the household if used. I dont trust anything that has been said its done. So new cabin and engine filters, oil change, and diff oil change, full inspection up on the lift, full detail, make sure all is good going forward. Well.........2 days later we make a turn and I hear whining or moaning. Only in a sharper turn. Especially cold. I am very familair with cars and thought it was a fluid issue?? It was full, it was correct fluid??> Took to the dealer....they agreed the sound was there, checked hubs, brakes, fluid. When the truck was warm and middle of day it was rare to hear it. They had no fix, stated I had a full warranty, come back if it gets worse. Bottom line it slowly went away over a month and never came back. I believe the new fluid had to work in a bit, but who knows??? Truck has been flawless. Putting the extended warranty on her, shooting for 100k, we love the truck.