Thumping when accelerating from stop

[GLA 250 4 Matic Dad]

Need diagnostic help. Thumping sounds from rear when accelerating forward from start. Lasts until reaching about 30 mph.

 

[AlwaysParanoid]

Need diagnostic help. Thumping sounds from rear when accelerating forward from start. Lasts until reaching about 30 mph.

Hey I'm having a similar issue but the thumping noise goes away around the 20mph mark. Did you ever figure out the issue?

 

[Gregg Mock]

we all have the same problem, has anyone got it diagnosed yet. To be specific, What is it?

 

[AlwaysParanoid]

we all have the same problem, has anyone got it diagnosed yet. To be specific, What is it?

I ended up taking it to a Mercedes dealership to get diagnosed. They took a look but couldn't find out the noise concretely on the test drive. They let me ride with one of the technicians to point out the noise. I live about 2 hours from the nearest dealership and by the time I got there, the noise was very hard to hear. The tech ended up saying it could be my tires in the cold and didn't charge me.

Noise does still exist unless I take it on longer car trips and then it's fine for awhile. Thinking I will know concretely one day if that isn't true or come warmer weather season and it disappears. I still have my suspicions on it being an axel of some sort, but what do I know.

Not sure if that is your case, but just wanted to shed some light on what I've experienced and what the dealership told me.

 

[AlwaysParanoid]

Just in case anyone stumbles upon this. I went in to get a service B and have the car checked out some more since warmer weather was upon us and I was still skeptical on the noise. The technician pointed out in a report that the rear flex disc was cracked. Getting it replaced now but all the symptoms check out with the aggressive thumps/feelings when accelerating to around 20 (i heard this gets worse as the disc cracks more at higher speeds), stopping, etc.

Really annoying getting this pinned down since the noise disappeared whenever I would drive it for a couple hours at higher speeds and only come back after a week or two driving it at city speeds.

 

[maesepp]

Hi, I had what i think you are all having issues with. All the garages could not find the issue. I asked them to change my rear diff oil and the problem has gone. Apperley it should be like water but mine came out like black sludge. I can it for 500 miles and changed again both times checking for metal fragments to see if lasting damage. Car has never run so smooth.

Let me know if this helps.

 

[Grommet]

I had the same problem on my gla 220 diff would shunt when driving slowly, changed dif oil and it’s quiet now, changed it myself, the drained oil was quiet dark, the new Mercedes oil had a clear yellowish colour to it and very thick compared to the drained oil.