Leaking R180 axle seals

[papak]

I picked up a used Subaru R180 LSD diff for my Birkin during construction. It was fairly low mileage (30k). I cleaned it up and resealed the side plates and rear cover. I also replaced the axle seals. Now that I have 1500 miles on the car, I found that both seals a leaking a little. It’s just enough to be a little messy under the diff. I show that this diff takes .8 qts of GL-5. Is this seepage evidence of overservicing or have the seals worn that quickly? I’ve got replacements but it’s a real pain in the ass to change them out if I don’t have to.

[Ferdl]

... I found that both seals a leaking a little. It’s just enough to be a little messy under the diff.

 

Are you sure the axle seals are leaking? I had a leaking axle seal and the oil was thrown away by the rotating axle towards gas tank, trunk and so on.

[papak]

I show a drop or two sitting inside the flare and a trail down the side a bottom of the housing. All of the seams are dry. It’s not “slinging” it to any extent. I’ll remove the upper plug this afternoon and check the level while I have it up on stands.

[papak]

I pulled the top plug on the end plate and can't feel fluid with my finger. This doesn't mean too much as the back of the car is jacked up and the clearance between the aluminum end plate and the diff is only about 1 ½". I show the correct fill amount to be .8 qt. I can't recall if this fills to the level of the top plug or not. Any info on this ?

[papak]

I checked on the a Subie forum and the fill is either 1.1 liters or fill to the bottom of the upper plug. Everyone seems to be an authority. I think I’ll fill to the upper plug and hold off on changing the seals as they aren’t slinging lube. Just a slight seep at this point.

[wemtd]

Papak - my notes on this are as follows:

Rear differential (Subaru R160 LSD): 2008 Forester XS. Oil capacity: 0.9L of 75/90 synthetic gear oil.

 

IIRC there is a lower drain plug and a second filler/plug above that: fill level should be to bottom of that plug (until oil runs out) on a level surface. But if you checked on an angle...

[oilteq]

Synthetic oils often produce less seal swell than petroleum oils. An 80W-90 petroleum oil may dry it up.

[papak]

I pumped in .3-.4l of Lubrimoly GL-5 75-90 into it yesterday (til it ran out). I then stuck my finger in the upper fill port and pushed a bit out, hopefully to compensate for the angle of the diff while jacked up. My assurances that it was a precisely calibrated finger. Given that it's from a Subaru, I figure that is precise enough. When I did the original installation, I replaced the breather with a -4 hose that vents to the top of the boot. I should have it back on the road later this week (I originally jacked it up to replace an intermittent Facet LP fuel pump).