Axle seal leaking....or something bigger?
 

Long story short. Swapped the 3.9 from my '02 into the MSM just before driving from Oregon to North Carolina. Not long after completing the drive, I crawled under the car to look at something and noticed the pax side axle seal weeping/fluid flung about around the area. So I drained the diff to top it off (another story for another time) and not exactly a lot of fluid came out. Filled it back up and have been monitoring the amount of leaking. It's been getting worse quickly. I cleaned everything up Thursday evening, have driven maybe 100mi between Friday and today. Got under there this afternoon to look around (was going to drain the trans and fill with the Ford stuff) and noticed a massive mess of fluid around the diff. I'm worried that I have a bigger problem than just an axle seal.....and if it will need to be rebuilt.....or if something is toast and not worth rebuilding. There is/was a noticeable 'whirring' that gets louder with speed and load....but I can only hear it when driving next to a curb. No vibration or any kind of grinding noises though. While under there just now, I did notice there is some play in the inner axle stub in/out....maybe 1-2mm.

Any ideas or things to look for/check?

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The play is normal. Check for up/down play where it comes out of the diff. That'll be a bad bearing and could be wearing out your seal. But if there's not a lot of play I'd just start with the seal, these diffs are usually pretty maintenance free outside of seals and fluid.

Alright, will check for up/down play. Thank you for the suggestion.

Yeah, my understanding and experience has always been that the TorSens are unlikely to have issues....unless run low on fluid. I think I'll be brave tomorrow and unbolt the hub from the control arms and peek inside to see if anything looks/feels out of place. I'm still going to have the local dealership do the seal replacement since I'm also having them do tires and alignment for me as well (they give a discount to the local Miata guys)...and given if there are any problems after, I can take it back.

Is it a known thing that axle seals can degrade that quickly to go from a light weep to dumping fluid in a short time?

I used to know a guy on here that went by the name of doppelganger. I heard he moved to Oregon, became a vegan, and joined a cult that didn't allow forum activity.

Since when did chickens become vegetables?


Well, I'm gonna be brave and unbolt the hub from the control arms and attempt to get the axle out to inspect/see if I can determine if its just the seal or something more.

Well, I think something is a bit wrong. There was damage to the seal at the 6 o'clock position that I could see as soon as the axle was out.

Upon getting the seal out, there are some metal shavings embedded in the seal....and where it was in contact with the axle, the axle is a bit shiny....not grooved or scarred though....can't even feel it with the edge of a razor.

I suspect the seal got damaged when the axle was put in, causing a slow leak on my cross-country drive, and that the fluid level got a bit too low and made something unhappy inside the diff.

So my plan now is to clean the seal seat, put the new one in, drain/flush the diff, stick a magnet-on-a-stick through the drain hole and swab around to get any potential shavings cleaned out of the diff.....then reassemble, fill and hope for the best for now.....hope it doesn't degrade any further. There was no up/down play in the axle before I removed it.

When you put the seal back in, be careful to not push the seal in too far. Don't ask how I know, twice. The lip on the diff casing is wider than the width of the seal. The axle has a little bevel inside. If the seal is put all the way in, it will leak.The outside edge of the seal just flush with the diff casing works. And be careful when you put the axle in to not push the seal farther in, my initial mistake.

Oh joy. It ended up a bit further than being flush. Great. Well, I'd feel far more confident doing it a second time now that I've done it once. Oh well. Given the metal shavings issue, it would be my luck anyway that it'll all have to come back out :/

Everything is back together. Before I filled the diff, I stuck a little bendy telescoping magnet in the drain plug hole and swabbed it around as best as I could. To my relief, it came out clean after multiple sweeps. Overall, the job wasn't as scary as I thought it would be. There were some awkward positions and delays due to some physical problems, but if I had to do it again, I wouldn't be nearly as anxious.

Once all was reassembled, I did a couple other things while in "work on car" mode (changed the trans fluid to the Ford SMTL, and installed some HIDs so I can see at night again) and took the car for a 20mi drive (wow, what an immediate shifting improvement the Ford stuff makes, which I noticed when I did it on the '02). Got back and looked under the car and all was dry. Will be checking it regularly over the next few days. I'm still surprised at the shavings that were embedded in the old axle seal.

Any Update? I'm having issues with diff leaking even used different seals. Both installs were this week, both still leaked after.