86' rear diff. gasket?

[Gold86Bimmer]

86' 528e, auto trans,:
My rear differential was leaking oil/fluid? and now it has stopped. Is it hard to repair leaking seal? Is there a gasket needed or just use high-temp gasket sealer? Any other advice or info welcomed.:dunno:

[jimoreno]

Are you sure that it stopped leaking or that it has run dry? You will need a 17 mm hex key to remove the filling plug and put your finger in it. If you don't feel the oil, you need to fill the case until it starts to come out. Also, if you are going this far, empty was left inside and fill with new lubricant.

Good Luck!

[Gold86Bimmer]

jimoreno, what do I fill it with..... regular motor oil or transmission oil???
Also, I just re-checked leak and it seems to be 'oily' on the passenger's side (right) of the differ..Is there a way to know whether the fluid is coming from the drive oil seals or the CV joint and not an 'old' gasket/silicone gasket (the cover where the filler bolt and drain bolt is attached to) ?
BTW- can this 'gasket'/silicone be replaced without major problems or tools?:dunno:

[jimoreno]

None of them actually. This I copied from a post in another forum:

Bentley calls for (and I am confident that the BMW owners manual also):
Manual Transmission 1.3 or 1.7 quarts SAE 80 API GL-4 MIL-L2105 non-hypoid
Differential 1.9 or 2.0 quarts SAE 90 GL-5

So it is SAE 90 GL-5 gear Oil that should be easy to find at your local auto part store.

Now for the second part of your question. If it is a CV joint you will have a nice line of grease aligned with the leaking joint under the car. When they leak the grease gets thrown out by the centrifugal force. This also means that your CV boots are shot and you need new ones. You can get them alone for replacement but they can be very tricky and messy. if you remove the driveshafts get some loctite as they ALWAYS get loose without and they will get destroyed when you least suspect (or need!) it. As I've said before, if you will be working with the car you need to get a Bentley's maintenance manual. Search for it on Ebay or Amazon as they can be pricey (around $50) but worth every penny. If you want to replace the side cover seal, just empty the diff, remove the driveshafts, remove and replace seals, fill diff and re-install driveshafts. The only special that I can think off is the 17 mm diff plug removal hex key and the hex bit for the driveshafts (if you are going this route do both sides).

Good Luck!

[Gold86Bimmer]

Thanks for the info and help.
I decided first do the easiest task and just replace the gear oil. I cleaned the areas of concerns (oil and grease) and will watch to see what happens next. If any grease or oil appears then I will get a better idea of what is next to do. Thanks again and I'm sure I will be posting more items that need to be corrected(....old car).:thumbup:

[kajwol]

I recently had my cv joints rebuilt on my driveshaft and looked under the car because of some differential problems.

Needless to say, I see the aforementioned grease on the undercarriage from the inner and outer cv joint and am beginning to think I got ripped off by the rebuilders.

fookers!

[jimoreno]

Actually the problem is the company that rebuilds the driveshafts don't glue the boots to the metal parts. See the following page (there are plenty of pictures so be patient!) close to the bottom, for information on how to seal the boots.

http://mysite.verizon.net/vze7aq8e/id20.html

One thing is for sure, this car is very clean!

Good Luck!

[Gold86Bimmer]

Update: So for so good......:thumbup:
After I cleaned and then drained the existing gear oil, I bought some SAE 80W-90, GL-5 from Walmart @ $3.00 a quart (little less than two qts. used). I figured that if I had to replace the gear oil again, I would not be paying more than i had too.
Anyway, I have not seen any oil or grease leaks.......at least for now. It could be that the gear oil used by the trans shop when they replaced my auto trans ( about three years ago??) was too thin and using this thicker oil has re-sealed itself ...???? I'll check again in about a week or so.

BTW- 10 mm hex bit socket was needed for my 86' filler/drain plugs.

http://i114.photobucket.com/albums/n255/626MazLazerRed/BMW-diff/adj7875_1_1.jpg