BMW E46 325xi 330xi Transfer Case Replacement DIY

Transfer case fluid changes are pretty important on E46 transfer cases.  NV 124 Transfer case in E46 3-series only holds .3 liters of MTF fluid and by 100K miles fluid becomes very dirty.  Unfortunately some people probably don't even know transfer case fluid should be changed.  In this article I will show you how to replace a transfer case in E46.  This project was done on a 2002 325xi automatic.

To do this job you will need 2 exhaust gaskets, 4 exhaust nuts, one liter of MTF-LT2 and transfer case input shaft seal.  It is also a good idea to replace the drive shaft center support and the drive shaft flex disk and a transmission output shaft seal. 

1.  Start out by removing all of the underpanels from front to back.  Remove the exhaust system and the reinforcement brace.

2.  Remove the heat shield.

3.  Unbolt the rear drive shaft from the transfer case.  Unbolt the center support and pull the drive shaft out of the transfer case flange.  You can ether tie the drive shaft to something and let it hang or you can unbolt it from the rear differential and remove it completely.  I removed my drive shaft all the way because the center support was cracked and needed to be replaced.  See my other article on replacing the center support.

4.  Unbolt the front drive shaft from the transfer case flange.

6.  Disconnect the transfer case breather line.

7.  Support the transmission with a floor jack and a block of wood.  Remove the large bolt that goes through the rubber mount, unbolt the aluminum mount from the body and remove the transfer case mount. 

8.  Remove the bolt on the front of the transfer case.

9.  Remove all of the bolts on the back of the transfer case.  You will need to lower the transmission down a few inches to be able to reach the top two bolts.

10.  If you are installing a used replacement transfer case be sure to install a new input shaft seal.

11.  Here is what the back of the transmission looks like so you know where all the bolts are.

11.  Don't forget to fill the new transfer case with fresh MTF LT-2 and reinstall everything in reverse order.