Oil on the axle flanking the rear diff

skiznits

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Was having a slow rear diff leak and was trying to see if I needed to service the housing.
I took a look down there and it looks like the leak is partially from the fill hole/plug region. Weird.

Also noted the oil flanking the housing. See the pic. Is that normal?

PXL_20220927_153908286~2.jpg
 
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skiznits

skiznits

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Was having a slow rear diff leak and was trying to see if I needed to service the housing.
I took a look down there and it looks like the leak is partially from the fill hole/plug region. Weird.

Also noted the oil flanking the housing. See the pic. Is that normal?

View attachment 120380
I'm thinking that oil is not where it's supposed to be. I checked the front diff and it's clean.

Anyone know why the fluid would be leaking from the fill hole? Diff Hasn't been serviced in years.
 

Gilaguy23

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You need to follow the breather vent hose to the end where there should, or was, a little plastic spring loaded diff breather. They get crapped up and dont allow breathing of the diff as it heats and cools. From what I see id say its plugged and causing the pressure in the diff which is making oil weep out at the axle tube where the diff vent starts as well as the diff cover plug. I'll add the rubber diff cover plugs get old and hard and don't seal great to start with. You can buy new ones also from Quadratec I believe. Just be careful if you try to pry it out as some of it might end up breaking off and ending up in the diff. Then it's a perfect time to remove the cover, clean out the 30 year oil crud, reseal and refill with new 80/90 gear oil.
 
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skiznits

skiznits

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That's great insight thanks.
How can I assess for tube patency after checking the actual valve?

Also wondering how I can troubleshoot faulty axle seals after assessing the breather vent.
I guess I can presume that it's ok if the oil stops leaking from the fill plug after I jimmy with the vent. That's pretty speculative I think but I'm I really have no idea.

Not even sure if that's where the axle seal would leak from anyway.
 
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Gilaguy23

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I forgot to add it may be overfilled also. The weeping from the breather tube typically indicates a plugged breather though. Far as axle seals go, they are on either outboard end of the rear diff in the axle tubes. Taking a quick look you'd see oily residue on the backside of the brake back plates. if you suspect they are leaking then pull a wheel and drum off and you'll see oily residue around the axle itself and if bad enough all over the brake parts and backing plate.
 
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skiznits

skiznits

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I forgot to add it may be overfilled also. The weeping from the breather tube typically indicates a plugged breather though. Far as axle seals go, they are on either outboard end of the rear diff in the axle tubes. Taking a quick look you'd see oily residue on the backside of the brake back plates. if you suspect they are leaking then pull a wheel and drum off and you'll see oily residue around the axle itself and if bad enough all over the brake parts and backing plate.
Ok thanks.
Yeah I don't think it's overfilled. I haven't topped it off.

I'm thinking maybe it's what you said a blocked breather.

I was going to try and get under and find the distal end. Looks like its buried under the rear driver fender.

What if it looks clean? Perhaps then it's blocked at the axle? How do I clean that out?
 
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skiznits

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Dang. What's the easiest way to get to the distal end of the vent. Before I mess w the light apparatus or the plastic covers under the wheel well thought Id hit here first again.

No good advice in a Google search. Only for tj and beyond.
 

Gilaguy23

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It's just a piece of rubber hose slipped over a barb fitting on the axle end. Yank it off, take a piece of wire or? and poke into the axle to make sure it's not plugged in the barb or tube. The end can be that hard to find and when you do pull the thing out and blow thru it to make sure it's not plugged and the cap on the upper end can move. After 30 ++ years things get gunked up. Keep in mind the trans,T case and front diff also have breather hoses with once the same vent valve on the end. Lots of guys run new longer lines up into the interior or high up under the hood if they plan on any deep water crossings. Don't over think the thing tear into it and learn.
 
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skiznits

skiznits

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It's just a piece of rubber hose slipped over a barb fitting on the axle end. Yank it off, take a piece of wire or? and poke into the axle to make sure it's not plugged in the barb or tube. The end can be that hard to find and when you do pull the thing out and blow thru it to make sure it's not plugged and the cap on the upper end can move. After 30 ++ years things get gunked up. Keep in mind the trans,T case and front diff also have breather hoses with once the same vent valve on the end. Lots of guys run new longer lines up into the interior or high up under the hood if they plan on any deep water crossings. Don't over think the thing tear into it and learn.
Is there a way to get to the valved end in the fender first. Would like to get a visual on it and I think it would be easier to assess that way. I could remove the valve end and the axle end and check patency.

Rather than pulling it all out from below. Then again maybe I misunderstood something.