Check out what I found on a X5 E70 with CPO,,,,while replacing and updating the ignition coils I found the rear input shaft seal leaking on the rear differential.
These are some of the tools needed for this job,,,,you can not do this job without these tools,,,,there no way BMW made sure of that,,,,the tool on the right that looks like it fits over a big nut,,,,that one is used to unscrew the driveshaft from the rear differential,,,,,the other one with 12 points is used to unscrew the rear differential final drive nut for the pinion,,,,,BMW has both these bolted down real tight and they used a lot of lock tight on the threads,,,,they use so mush that you have to warm it up to loosen the lock tight.
Here you can see the driveshaft being unbolted from the rear differential,,,,,you can see some threads coming out also you can see all the lock tight on the threads.
This is the big nut you just saw,,,,,that you turn to release the driveshaft from the rear differential,,,,,you have to replace this big nut when performing this job,,,,,,I have seen some people chose not to,,,,,and get in trouble later on,,,,what happens is all the lock tight and all the torque of the driveshaft,,,,puts a lot of stress on this nut,,,,when you replace it and tighten it down,,,,BMW say to wait 2 hours before driving to cure the lock tight.
bmwtechnician 
Life just keeps getting better.
-Oasis
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How common is this issue. My dealer tells me being they stock the parts, it is common enough. I just purchased a 2013 E70 X5 3.5I. I have replaced the pinion seal on other vehicles, I have not attempted this. Please let me know.
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It’s not a real common issue,,,this is not a backyard job,,,you need those special tools to perform this job.
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I have the tools available and have done plenty of pinion seals on Chevy trucks. I plan to do most of the maintenance on this vehicle. Does orientation matter when the driveshaft is disconnected?
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No that doesn’t matter
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So sir, other than the special tools is there anything that makes this job difficult? I see a lot of heat shields and covers, although it seems pretty straight forward. Disconnect the drive shaft, which will then expose the seal on the differential. Bearing should be able to remain intact. Replace the seal, nut and apply thread lock. In a very basic terms and steps
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Replace seal and get new nut which already has thread lock applied,,,,once driveshaft is tightened you must wait 1 hour before driving car to let thread lock cure,,,,driveshaft nut turns opposite direction to loosen,,,,again you will need special tools,,,sorry this is no Chevy or Ford drive shaft removal those are easy,,,,I hope you listen to me on this job,,,,if not good luck
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Where Can I get those special tools?
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A company called Beley might have the tools
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Thank you. Did replacing the but stop the leak? Is there a chance that it could leak due to a drive pinion shaft seal?
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Sure the pinion shaft seal could lea
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I got all the tools from friend at BMW here locally. The pinion seal was leaking. I replaced the star bolt and the pinion seal. As you stated this was a terrible job and I would not recommend trying it home.
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Macho7337,
For removing a star bolt, how did you achieve 500 Nm torque as stated per BMW TIS? I’ve read if not properly it could lead to a failing rear differential…
I’m very interested to know.
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Sorry for the late response. I was not able to torque it to spec. Although I counted threads and amount of turns it took to come loose. It has been holding so knock on wood. If I had to do it again I would just replace the rear diff. It would have saved time.
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Lol,,,,maybe you would have saved time but not money,,,,the rear diff is not cheap
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