Rear Diff Leak

4

4runnerWiniarski23

New member
Hi guys,

I was under my truck the other day and I noticed my rear diff has been leaking slowly. I noticed it looks to be leaking at the breather. I recently had a East Coast Gear diff installed so I do not believe its the pinion seal.Fluid running down from the breather to the bottom and then throwing it back.

Is it possible that the breather seal is leaking? Warmer weather causing the fluid to be pushed up out of the breather? Is the breather an NPT thread that maybe needs some Teflon?

Also recently getting P0440 and P0446 after changing plugs. Gotta do some more research on where to start with these. Could be a evap hose pluged or disconnected? Gas gap?

Thanks in advance.

Alex W.
 
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I did check the fluid level because I was concerned it was low. I removed the fill plug, no fluid came out. I continued to add fluid until a little fluid dripped out out, replaced fill plug.

Breather sticks out the top of the axle housing, so am I wrong to think that in order to over fill it enough for it to come out of the breather it would be difficult considering the fill plug is much lower.
 
4runnerWiniarski23 said:
I did check the fluid level because I was concerned it was low. I removed the fill plug, no fluid came out. I continued to add fluid until a little fluid dripped out out, replaced fill plug.

Breather sticks out the top of the axle housing, so am I wrong to think that in order to over fill it enough for it to come out of the breather it would be difficult considering the fill plug is much lower.
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I believe the correct fill is just below the fill hole about 1/4"
 
If it was the pinion seal, you'd see oil slung all over the place since it's a rotating part. That should rule that out pretty quick. I would get the breather replaced asap because all that pressure not escaping could cause your axle seals to leak, and then you'll have bigger fish to fry.
 
Agreed on ruling out the pinion seal.

Breather is cheap enough I will get that this weekend.

If the fluid is high then I can see it being pushed elsewhere instead of out of the breather and there is zero fluid at my wheels or anywhere else for that matter.
 
RedSled said:
I believe the correct fill is just below the fill hole about 1/4"
Click to expand...

The correct level is right at the bottom of the threads of the fill plug but the FSM says if it's within 5mm of the bottom of the fill plug threads then it's OK. Nobody is going to try to fill exactly to 5mm or 1/4" from the lip. When you fill a differential, transfer case or manual transmission, you fill until you see gear oil spilling out and then you're good. This is auto mechanics 101.

If you're getting gear oil out the breather it's because you either overfilled because you filled the diff while it was at a slant downward towards the front of the rig or the breather is sticking and the pressure is building higher than normal and when the pressure finally overcomes the sticking breather oil is joining the air escaping.
 
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So i went and tried to grab a picture of the leakage at lunch time. The picture is tough but you can see the fluid has been running from the breather down the left of the pumpkin for some time.

I removed the breather and cleaned it out. It is moving freely without hesitation, I even blew some air and feel it coming out. still not ruling out the fact that the internals could have an issue.

I decieded to add some teflon tape to the threads to help prevent any leaks. If the diff is overfilled it will continue to leak until its at a happy level. I will monitor it.
 

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the gear oil used is not the problem the breather threads are the problem . you can't over fill ....... you fill to the bottom of fill plug.

if it still leaks at around the breather then you buy new breather. could be they cracked it.
 
Does anyone have the part# for the OEM plug? or is doing the diff extender really the only option.

I plan on taking the truck some 800 miles this weekend and would like have this solved. My plan is to get a new plug or extender and add some fluid. The leak should stop then. I agree the threads could be the culprit.
 
4runnerWiniarski23 said:
Does anyone have the part# for the OEM plug? or is doing the diff extender really the only option.

I plan on taking the truck some 800 miles this weekend and would like have this solved. My plan is to get a new plug or extender and add some fluid. The leak should stop then. I agree the threads could be the culprit.
Click to expand...

I just replaced mine as well. 90930-03031
 
Update ****
Didn't take the truck over the weekend with the fear of it loosing to much gear oil in the back. Put the new breather in, threaded down fine and tight. I tried to feel if the threads on the housing weren't any good but the new breather went in smooth.

Still looks to be leaking, and I cannot for the life of me see anywhere else where it could or would be leaking. The 3rd member seal is all dry, pinion seal dry, just the breather leaking what looks like oil blowing up through the breather not at the threads though it is tough to see when everything's covered in oil and it's dark.

Do we think it's the synthetic I added?
Could the level be low again and oil Temps getting high causing it to blow out the breather more?

I' am at a loss and days away from bringing it to a mechanic for second opinion. (other topic but any good mechanics near me you guys know of 12590 zip or hudson valley NY region)

But any other ideas greatly appreciated

Thanks

Sent from my SAMSUNG-SM-G920A using Tapatalk
 
Mark_BC said:
Why don't you add the diff vent extender mod so there's no way the oil will migrate that high?
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You bring up a valid suggestion. I went ahead and read the eat coast gear supply suggested oil, Lucas non-synthetic 85W-140, much heavier then I put in when i was topping off.

Going to drain and fill with Lucas non-synthetic 85W-140 and see if the leaking stops. If not then extended breather. Truck could use a diff fluid swap anyway after the new differential break in.
 
Swapped the new breather plug about 2 weeks ago, and even swapped in the heavier fluid.

It still seems to be leaking out of the breather and I am really at a loss to why. I am at the point of bringing it to a professional but wanted to see what you guys think?

I can also swap out the breather and put in the breather mod and run the breather line up farther in hopes that the fluid would never make it up the line.
 
I'm not sure why you keep getting oil coming out of your breather but if I were you, I would do the extended breather mod. For $20 it will probably solve your problem.

If oil were to puke up all the way up after the extended breather mod, something is seriously wrong.
 
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