2018 GLA250 4MATIC Transfer Case
I just came back from the dealer. Merc Benz service foreman informed me it is the rear differential. Ugh, 6K repair bill. He disconnected the rear differential solenoid, and the car ran fine. Next time trust my gut, even for a vague sound. If I would have gotten the car there 8K miles earlier it would have been covered under warranty...sigh
Last edited by LTK; May 25, 2021 at 07:00 PM. Reason: Service update, problem diagnoised
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I was concerned that the rear diff was bad, so I found a good used rear diff on eBay for a fair price with free shipping, from a 35K donor vehicle. It was from a reputable dismantler seller, so I was willing to take the risk on the part. While I was waiting for the diff to arrive, I drained and refilled the rear diff fluid. I was able to do it without even raising the vehicle. It was super easy and fast. While I was under the vehicle, I reconnected the solenoid for the rear diff. And then I drove the car, and the problem was solved! It drives like a dream, and no noise! I always say that what scares me the most is what I can't see. We can't see the fluid in these closed cases, so we need to change the fluids if we have any doubts, especially as our cars gain more miles. Do it sooner, rather than later, especially if you want you vehicle to last. I appreciate the message about doing it twice, and now I will. Again, it's super easy, fast and cheap. I have a feeling that the rear diff fluid in my vehicle was never changed in 213K miles. How sad.... :-(
On a side note, I had a 30-day return availability on the good used rear diff that I had purchased, so I waited for a bit while I drove the car. The rear diff was fine, so I returned the eBay diff, without ever opening the packaging. It cost me $135 for return shipping, but I felt confident that I had solved the problem with a simple fluid change. I didn't want to store the eBay diff and I just wanted my money back. I was willing to pay the $135 return shipping penalty for a purchase that I made in error.
So sorry that the OP may have been fleeced by the dealer, when they probably only needed a fluid change in the rear diff.
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