Here is some good information on the subject..................
http://www.sl113.org/forums/index.php?action=search2In general, leaks are usually caused by poor installation or over-filling of the unit. Also make sure that the vent is not plugged up with dirt. Make sure the axle tubes are loaded and parallel to the ground before checking the level. If you let them hang down you will over-fill it. Besides the rubber bellows clamps, clips are used to hold the seam of the split axle boot together. A special tool was used to install the clips but they can be installed with other standard tools if necessary. At present time, Mercedes no longer supplies the original clips so the special tool is no longer relevant unless you find some NOS clips. Instead standard upholstery hog-ring clips are now supplied by Mercedes. Standard hog-ring pliers can be used to install them. Mercedes crazy cost on these hog rings is $9.00 ea. !
I found a box-type metal staple which resembles the original clips. I do a minor modification to them so they are nearly identical to the originals. In this way I use my original factory tool to install them instead of the hog-rings. However the hog-rings should work just fine. It is normal for some
slight seepage
to occur at the boot seam even after correct installation. Some owners will use an adhesive to seal the seam. This is not recommended by MB but seems to work fine. Be aware that the front pinion seal of the rear differential is also a frequent source of leaks.
It is very difficult to install the split axle boot with the axle in the car when the fuel tank and/or the axle cross-spring in place. But it can be done.