I originally posted this on diesel discussion, but it would apply to any 124 chassis Mercedes. I am posting it here in the hopes that someone in this forum will have ideas as well.

The final drive (differential) on my 1987 300TDT (S124) seems to still be leaking after the replacement of many seals and parts. The leak seems to be occurring on the right side output seal.

The final drive has been serviced several times by my local MBZ shop and several solutions have been tried to correct the problem.

1) Three sets of output seals have been tried. The first two were Elring and the last was a genuine MBZ seal set.

2) New flanges were installed on both sides of the differential. (The seepage occurred with both the old and new flanges.)

3) The seals were "set in" at different depths so they would ride on different areas of the flanges to see if that would correct the leaks.

4) The final drive vent was verified as being clear and open.

5) Initially the fill was Redline 75W-90 GL-5 synthetic gear oil and this was switched to regular 80W-90 gear oil. The final drive leaked with both oils. The final drive has been refilled with the Redline 75W-90 GL-5 gear oil.

6) The fill level was correct in all cases. (All work was performed by factory trained ASE technicians familiar with MBZ vehicles.)

The owner/technician is out of ideas on what might be cause the seepage of oil since the solutions above were tried.

I am looking for ideas on what might be causing the oil seepage from around the output flange on the right side.

The only thing I can come up with is:

Crack in case of final drive? There is no obvious cracks, but a magnaflux would have to be done to check for cracks. The only solution would be a new final drive.

Thanks in advance.

-Steve

__________________
1987 300TDT smoke silver w/ burgundy leather interior
2000 VW Passat wagon indigo blue w/ beige leather interior
1985 Mustang SVO
1970 Chevrolet K10 fleetside, shortbed