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Discussion Starter #1
15k - 20k ago I changed out my front/rear diff fluid and transfer case fluid for the first time since buying my '08 JKU a couple years ago. Just checked again last weekend, and rear fluid was black and overfilled quite a bit. I drained the diff and removed the cover. The drain plug had black silty (shavings?) all stuck to it and my gears were also still lightly coated with that black stuff(mixed in with the fluid). I wish I had taken a picture now.

I also recently found my rear axle seals to be leaking on one side a few months ago and decided to ignore it. Now I am noticing a metal crunching/grinding sound when I am driving over 10 MPH, this is why I was investigating my diff to begin with, and come to think of it, I had been hearing a ticking noise for a long time but couldn't figure out the source. I can probably safely assume my rear bearings are about to give way.

I did not overfill the rear diff, and the front diff was clean and normal when I just checked. Is there a possibility that the grease from my failed bearing(s) is mixed in there and that is maybe where the black color and shavings and overfill are coming from? The amount of extra fluid seems excessive for grease, tho, it was at least 4 - 8 oz overfilled if I had to guess.

Would I be OK just replacing the bearings and seals, or is it advisable to replace the entire axle shaft? Money i$ tight!

G2 OK,? I have to use my 4WP credit card for this purchase. For goodness sake, I hope the gears are OK, they seem to be for the past week after I did my inspection and refilled.

I refilled it with some full synthetic stuff from O'Reillys, and went on my merry way. I hope I can find some good advice here.

Thanks,

G!
 

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So....is this overly complicated, or did I answer my own question. I *did* read the other posts about black diff fluid, and I *do* have a tendency to be long-winded. I'm primarily concerned with the "shavings" and if I can get away with only bearings at this time if the axle shafts appear OK. If I do have to buy axles, are the G2 brand sold at 4WP better than stock? Budget is tight so no bad ass axle suggestions please.
 

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The blackish fluid can be somewhat normal for the rear. The black silt stuck to the magnet is also normal if not overly excessive and if no other metal chunks or shiny shavings. MAYBE why it appears over full is because maybe water got in your differential, perhaps through the vent tube. Did you go through high water? Water would turn the fluid brownish color. Maybe water did get in there and rust up some gears/bearings and hence your grinding sound.
 
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