Vehicle: 2011 E350 4Matic. 22K miles. 47 months in service.

Issue: Drivetrain noise. Sort of a "thwop-thwop." Sounds a bit like something stuck in a tire or rubbing on a rotating driveline part. Most apparent at 10-20 MPH under acceleration and after vehicle is driven about 10-15min. Sound file attached; headphones recommended.

Diagnosis from MB Dealer: Problem in the transfer case. Attempt to solicit more precision was unsuccessful.

Remedy: R&R a re-manufactured transmission/transfer case under warranty. Dealer advised that transfer case only would not be replaced.

Cost: Under warranty (just barely). Warranty paperwork showed an approximate $7K charge.

Repair time: 6 business days (parts not immediately available).

Comment: Surprising expensive, low mileage failure on a component that is not complex and should be robust. Lack of a root cause does not engender confidence in the vehicle.

Hope this helps anyone with a similar affliction.

 

Glad you got that in under warranty. Was the dealer quick to diagnose or did you have to record it to prove it to them?

 

Dealer quickly acknowledged and diagnosed the problem without the audio clip.

Good response from the dealer on this issue.

 

Yup 4matics are known to have problems.
22k miles, 5 years old. likely 2010 production date.
Probably needed differential fluid two years ago. Judging by the low miles i imagine short trips, possibly driven hard before optimum temperature and shut off. Long periods of weeks not being run. Sedentary oil. Just guessing

Glad it was fixed under warranty

 

Production date was 24 Mar 2011, so just over 4 years old.

Car not driven really hard, but never stressed until fully warmed up.

Mission profile is pretty typical for suburbia; not an atypical number of short trips. Low mileage is not a result of short trips, but rather due to vehicle not being primary vehicle in the household. Used more for longer voyages.

The vehicle never sits for more than 3 days (except when being repaired by dealer).

The issue was with the transfer case mounted to the rear of the automatic transmission, not one of the differentials. The Maintenance manual does not show a required fluid change interval for the transfer case. If you have specific information on this, please advise. Thanks.

I am skeptical that this failure was a result of improper fluid change interval or vehicle mission profile.