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Discussion Starter · #1 ·
Hi all,

I've had my GLA 250 4Matic for a little less than a month now, and i've noticed a very subtle "clunk" noise coming from what feels like the rear of the vehicle while slowing down and coming to a complete stop. Typically it seems like it only does this the first few complete stops that I make in the car......like in the mornings when I pull out of my garage and am driving through the city to get to the interstate, when I approach red lights while slowing down, immediately before I come to a complete stop, it almost feels as if someone slightly tapped my rear fender (I thought someone did the first time I noticed it!)

Not quite sure what the issue could be and if it is related to the brakes/suspension or transmission? I have never experienced the violent jerks other GLA owners have had problems with while shifting into different gears, and I only seem to experience the subtle clunk while in drive (eco/manual/sports doesn't seem to make any difference). I can't imagine it is tranny related because it does not match up with the 2>1 downshift and I am only applying brakes, not gas.

After about 15 minutes, the clunk seems to go away. Has anybody else experienced this? I've done some research online and the issue seems to be well documented for various types of cars, but the diagnosis is always related to worn parts or after a new brake job, etc. My GLA has 5k miles on it.
 

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I have the same issue. I thought it might be an exhaust burp initially, but it is definitely a clunk in the first few minutes of driving. I have less than 3500 mi so far. Have not yet had it in for service.
 

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i've got the same issue and it goes away too after driving for a bit.

i dont know how true, but the research that i've read up on says it's the cold fluids and the rear diff disengaging (iirc) that causes the clunk. once the fluids are up to temperature and at the right viscosity, the issue goes away.
 

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i'd say the clunk would happen more often and for longer duration in winter because it would take longer for the fluids to get up to temperature.

i'm keen to see what other owners experience and if the majority of you don't have this issue, then it blows the theory i believe out the window and i should take mine back to the dealer for a check up...
 

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I've only had mine since June, so it's only been summer months so far.
 

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i'd say the clunk would happen more often and for longer duration in winter because it would take longer for the fluids to get up to temperature.

i'm keen to see what other owners experience and if the majority of you don't have this issue, then it blows the theory i believe out the window and i should take mine back to the dealer for a check up...
That's what i've noticed too and usually it takes 10-15 minutes of the engine running and another 10 of driving for everything to feel 'worked-in' with most of my vehicles in winter.
 

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Discussion Starter · #12 ·
Just wanted to provide everyone with a quick update. I scheduled a service appointment to have the clunk looked at. While I was explaining the issue over the phone, service asked me if I had any issues with hard downshifts as well. After reading up all about this, I assumed it was just the way the car ran because I have certainly noticed it, but it's been identified as "normal" operating conditions especially in sport mode and with the DCT.

Anyways, I dropped the car off this morning and got a call later in the afternoon saying there was a service bulletin to update some software, which they did. All of the issues have completely gone away, no more clunking when coming to a stop, and the transmission is SO much smoother when coming to stops in sport mode.

I will say that the biggest difference that I noticed immediately was the responsiveness of the throttle/pedal primarily in first gear from a stop, but also in all gears and speeds. There was so much "play" with the pedal before the car would actually go, and it took a lot of feathering on the gas and pressing down over an inch before I would accelerate. This issue has been identified several times on these boards and is common with the CLA too but I have to say that after the software update they performed, it was 100% better.

Long story short, if you are experiencing any of these issues, make an appointment!
 

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I dropped the car off this morning and got a call later in the afternoon saying there was a service bulletin to update some software, which they did. QUOTE]

Do you have a record of the update on your service receipt? Is there a MB bulletin number listed?

The reason I ask is that I had my GLA in for the A service recently and asked about a transmission software update having seen that mentioned on this and other GLA boards. The service advisor told me he looked in the system but didn't find any updates available. This is confusing to me, making me wonder if my local service advisor is correct, incompetent, or lying. My GLA250 was a July 2014 build, so is unlikely to have latest software. On the other hand, have not noticed any clunking, and transmission shifts smoothly from dead stop.
 

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I'm having a similar issue - audible clunk under the same circumstances. Brand-new 2016 GLA 45 AMG, 1300 miles and I broke it in very carefully. Didn't even know what 'kickdown' was until this week so pretty unlikely that I ever did it during the first 1000 mi. Guess I'll bring it in for a checkup...
 

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I'm having a similar issue - audible clunk under the same circumstances. Brand-new 2016 GLA 45 AMG, 1300 miles and I broke it in very carefully. Didn't even know what 'kickdown' was until this week so pretty unlikely that I ever did it during the first 1000 mi. Guess I'll bring it in for a checkup...
Hi there just wondering how you got on with this issue as my car is getting checked out today?
 

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I have this same problem. 2016 GLA 45 AMG with 40k miles.

When I come to a stop, or almost come to a stop, the car will make this deep thud sound "as if" the gas tank was loose and was hitting something. Having owned a GTR with DCT, I knew these transmissions are not the smoothest nor the quietest, so I assumed it was just normal operating quirks and noises.

Although the car has had all its scheduled maintenance, I'm thinking that if you don't ask for this software upgrade, it will not get done. So I will probably bring it to MB in Colorado Springs and see what they say.

Thank you for the comments and recommendation provided above.
 

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I have this same problem. 2016 GLA 45 AMG with 40k miles.

When I come to a stop, or almost come to a stop, the car will make this deep thud sound "as if" the gas tank was loose and was hitting something. Having owned a GTR with DCT, I knew these transmissions are not the smoothest nor the quietest, so I assumed it was just normal operating quirks and noises.

Although the car has had all its scheduled maintenance, I'm thinking that if you don't ask for this software upgrade, it will not get done. So I will probably bring it to MB in Colorado Springs and see what they say.

Thank you for the comments and recommendation provided above.
I had the same problem. Ended up being the PTO in the transmission starting to fail. It transmits the rough engagement sound thru the driveshaft to the differential. That's why you hear it from the back. Check the breather on the differential. I believe the manager said the clogged breather can create a similar problem as well.
 

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So glad to see folks posting about this problem in the past few days versus 2015.... I have a 2018 GLA250 4 matic and the back end noise is awful. Sounds like bass booming in a bad song at times, especially when I turn slowly and hard right into my driveway. When coming to a complete stop the majority of the time, I hear and can feel a "thud" from the trunk area. I drove to the dealership a few weeks ago (45 minute drive) and of course the sounds would not duplicate with the mechanic in the car. I was told they would attempt to duplicate it on a "cold start" the next day but when they attempted it, of course they heard nothing....
Did you get resolution for the problem?
 

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I have this same problem. 2016 GLA 45 AMG with 40k miles.

When I come to a stop, or almost come to a stop, the car will make this deep thud sound "as if" the gas tank was loose and was hitting something. Having owned a GTR with DCT, I knew these transmissions are not the smoothest nor the quietest, so I assumed it was just normal operating quirks and noises.

Although the car has had all its scheduled maintenance, I'm thinking that if you don't ask for this software upgrade, it will not get done. So I will probably bring it to MB in Colorado Springs and see what they say.

Thank you for the comments and recommendation provided above.
Did you get resolution of the problem?
 

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Hey everyone I had the same thing happen on my 2015 gla250 4matic. After 3 different diagnostics done the and the final done by Mercedes. All 3 came to the same issue which is the rear differential needs to be replaced. Which totally sucks because it’s not cheap. Also what is sucks even more is Mercedes’ knows of this problem but only put out a TSB on this problem and not a recall. I don’t understand if so many of these cars are having the same issue why they won’t just recall it. But long story short I am now having it replaced at the fine price of $5600.00!!!! …….ummm yea, you heard correct that is how much it is costing me. So I pray I never have to have it replaced again. So if you are having the same problem have that checked out! I’ll update you all once I pick up my car from Mercedes’
 
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