My 91 4matic with 134k has developed a leak from what appears the rear of the transfer case. I had a big leak of oil after driving on slick roads for a day. Now without engaging the tranfer case I have a very small leak showing up on the floor. Just a few spots. Anybody been through this? Is there a repair short of a new case? Appreciate any and all help.

 

Hi Jay, Unfortunately you have the beginnings of what every 4 matic owner will eventually experience, transfer case leaks and problems. Im assuming that the 4 matic light is out, does flash twice on first start ups, (normal) but you have a leak probably from one or both of the output shafts. Get to a MB savy mechanic, (forget the dealer unless your filthy rich), and have him drain the AT fluid which resides inside the T/C. If it is mixed with Hydraulic fluid, you need a r/b T/C installed. You can find them on the web. Its big bucks though. Otherwise, if clean AT fluid comes out from the drain plug, you probably just need to reseal the output shafts. Try www.autohausaz.com for parts first. The cost of seals from the dealer arent too bad either. The transfer case also contains the 4 matic clutch which is a self machining servo that toggles the front drive off at 12 MPH. It does eventually go south and will need service. You could shut off the front drive, reseal the unit and top off the AT fluid, but again you will be driving a two wheeler at that point.... Good luck....
There are no known mechanic in a bottle tricks for you, sorry.....

 

Thanks for the input. I drained the TC and the fluid was contaminated. Refilled and put in "test" mode. Driving in 2wd I guess at this point. I am still confused as to how the 4matic works. I understand there are 3 modes. Also, that the center differential is locked on with spring pressure and relies on the hydraulic pressure to hold it off or unlocked position. Every start from a stop it goes to step 1 up to 12mph. Once movement is detected and no slipage the lock is disengaged and car goes to 2wd. If that is true then am I in step 2 with the TC differential locked with 50/50 distribution front and rear when in the "test mode"? What a complicated system!