I have had this car for about a year, 87 300D with 94K miles (current reading). When I got the car, the differential looked wet and oily. Now, I can see light blue oil dripping near the differential after driving. I checked the oil in the differential. It was a little low and the oil was also light blue. Upon close examination, the pinion seal looked good: no oil on the surface of the seal. The whole area under the car around the pinion seal was oily. The oil seems coming from the end of the rear drive shaft (this is the shaft between the tranny and the differential) before the 3-finger which is attached to a flex disk. Is the oil coming from inside the rear drive shaft or the differential? How to fix it?

Thank you for reading.

David

[This message has been edited by be459 (edited 04-21-2000).]

Dave, if you are sure the pinion seal is not leaking, (I doubt that it isn't), then the only other prospects are the halfshaft seals on either side of the case are leaking or the case is cracked. The driveshaft has no internal lubrication. Another possibility is that the oil may be coming from somewhere in front of the differential, although, I don't know of any blue ATF out there or engine oil for that matter.

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Jeff L
1987 300e
1989 300e
1987 BMW 325

[This message has been edited by jeffsr (edited 04-21-2000).]

The oil has to be coming from the differential. I presume it is passing between the pinion and the flange along the splines.

I would disassemble and reassemble with a loctite product for spline sealing. Be sure not to overfill.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Steve and Jeff, thank you for the reply. The halfshaft seals and the pinion seal do not have any visible oil leak. I saw a very minor leak from the sensor on the differential but the big leak appears to be far from the sensor. I will follow Steve advice to fix the problem. At the same time replace the rear flex disk and pinion seal which are still looking good but they are 13 year old. Parts are cheap comparing to the labor.

I will come back for more advice if I have problems or surprise during the repair.

Thank you very much, again, for the advice. Happy Easter!

David

PS: The light-blue differential oil appears to be the original oil from MB, expensive stuff.


[This message has been edited by be459 (edited 04-22-2000).]

David,

Before you remove the pinion nut, use a sharp chisel to positively mark the position of the nut to the shaft.

Upon reassmbly be sure that you do not tighten beyond this mark. The nut needs to be tight but if you further crush the crush sleeve the pinion bearings are toast.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Steve,

Thank you for the tip. Otherwise, I would possibly overtighten the nut.

David