Leaking (blowing!) diff fluid. Hole in axle housing?

[EricStanley]

Hey all
2020 JTR. Not stock by any means. Was getting gas today and noticed some fluid where it shouldn’t be and realized I was smelling differential fluid. Looked under and saw that everything is covered in differential fluid. I was 90 miles from home on a Sunday, so $625 tow bill later I got it home and maybe? Found it? To each side of the differential there are what appears to be filled-in holes on the upper and lower (front and back) on the axle housing. One of them appears to have been punctured maybe? But it looks pretty clean for it to be blowing fluid.

I’m attaching pictures of the questionable one and one that is on my wife’s JLUR for reference (it’ll be obvious which one is which).

Is this common? Something others have seen? Am I barking up the wrong tree?

I haven’t taken the dif skid plate off yet, so ~maybe~ there’s something hidden I’m not seeing, but I don’t see any other obvious things to look at.

What makes me question it is that the fluid is… nearly everywhere from the fuel tank back… the entire underside of the bed, suspension components, etc - but it isn’t in the wheels or anywhere near the axle seals (completely dry and clean there) so I’m ruling that out.

Is there a chance this coming from the point where the drive shaft enters the differential? Where would you start looking?

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[Rusty PW]

In the first picture. That hole is what is called a plug weld. It's a weld in a hole to hold the axle tubes in place.

In the second picture. That hole is for a tool called a coconut spreader. When installed. It spreads the diff housing apart to help install the carrier unit, or to remove it.

 

[jac04]

For fluid to get slung everywhere like that, my bet is that the pinion seal is leaking. So, I would wipe everything down and focus on that area as the source of the leak.

On the JKs, there have been reports of those plug welds weeping oil. Not sure I've heard of it happening on the JL/JT, but if it were leaking it would be a very slow leak. So, I doubt that is your leak.

 

[EricStanley]

In the first picture. That hole is what is called a plug weld. It's a weld in a hole to hold the axle tubes in place.

In the second picture. That hole is for a tool called a coconut spreader. When installed. It spreads the diff housing apart to help install the carrier unit, or to remove it.

Good info. The plug weld is what I’m referring to. The first pic is my JTR. The second pic is the wife’s bike stock JLUR with no issues.

 

[EricStanley]

For fluid to get slung everywhere like that, my bet is that the pinion seal is leaking. So, I would wipe everything down and focus on that area as the source of the leak.

On the JKs, there have been reports of those plug welds weeping oil. Not sure I've heard of it happening on the JL/JT, but if it were leaking it would be a very slow leak. So, I doubt that is your leak.

Good to know and agreed that it would be weird for the plug weld (as I now know it to be) to spew fluid like that. It does seem like it would have to be thrown, not dropped.

I can and will do some searching… but… how hard of a job is it to replace that pinion seal if that’s the source?

 

[Rusty PW]

For fluid to get slung everywhere like that, my bet is that the pinion seal is leaking. So, I would wipe everything down and focus on that area as the source of the leak.

On the JKs, there have been reports of those plug welds weeping oil. Not sure I've heard of it happening on the JL/JT, but if it were leaking it would be a very slow leak. So, I doubt that is your leak.

Every manufacturer that makes solid axles has some axles the weep at the plug weld. It's nothing new. I've seen Fords, Chevys, Dodge/Ram, and Jeeps all weep there.

 

[OldButStillJeeping]

I would do this:

Attempt at your own prerogative.

See if it is oil or transmission / transfer case fluid, brake fluid or anti-freeze, or gasoline, etc. by using the texture and smell method. Mark the box of what fluid it is and go forward. But If you can't tell...

Then De-grease the mess after pulling the pumpkin skid plate. Check fluid levels and if the transmission fluid, engine oil, power steering, brake fluid and anti-freeze are good: Then drive it a little. See where it seeps.

A serious pinion seal failure usually throws gear oil in a circle at the pinion. Bottom of truck bed, frame rails, etc in a fuzzy line perpendicular to the driveshaft.

I had a brand new FRAM brand oil filter have a pinhole from the factory. 1980s. Filter hole blew engine oil onto the inside of the front tire and oil was then thrown everywhere under the truck. (1978 Toyota Hilux). Needless to say, I don't use FRAM oil filters anymore.

Good luck. Please let us know what it is.

Be well. Jeep on.

Eric

 

[Stan H]

My money is on pinion seal .. pinion seal is easy to fix but you want to make sure and torque the pinion nut back down correctly after replacing the seal and reinstalling the yoke and pinion nut . There are several videos on you tube showing this procedure . With torque values included.

 

[DanJT]

My money is on pinion seal .. pinion seal is easy to fix but you want to make sure and torque the pinion nut back down correctly after replacing the seal and reinstalling the yoke and pinion nut . There are several videos on you tube showing this procedure . With torque values included.

Agreed on the pinion seal. With that said, do you have a lift? reason I ask is the driveshaft looks a little off and may be vibrating causing said leak at the pinion. Just something to look into!

 

[ShadowsPapa]

Oil, for that matter, other fluids, blow BACK. I see oil ahead of the axle tubes.
The driveshaft looks straight to me, but I see spots on it and the pinion area seems wet in the pictures.
The leaking area will have the least fluid, it will be worse behind the leak.

 

[Sweetums]

Hey all
2020 JTR. Not stock by any means. Was getting gas today and noticed some fluid where it shouldn’t be and realized I was smelling differential fluid. Looked under and saw that everything is covered in differential fluid. I was 90 miles from home on a Sunday, so $625 tow bill later I got it home and maybe? Found it? To each side of the differential there are what appears to be filled-in holes on the upper and lower (front and back) on the axle housing. One of them appears to have been punctured maybe? But it looks pretty clean for it to be blowing fluid.

I’m attaching pictures of the questionable one and one that is on my wife’s JLUR for reference (it’ll be obvious which one is which).

Is this common? Something others have seen? Am I barking up the wrong tree?

I haven’t taken the dif skid plate off yet, so ~maybe~ there’s something hidden I’m not seeing, but I don’t see any other obvious things to look at.

What makes me question it is that the fluid is… nearly everywhere from the fuel tank back… the entire underside of the bed, suspension components, etc - but it isn’t in the wheels or anywhere near the axle seals (completely dry and clean there) so I’m ruling that out.

Is there a chance this coming from the point where the drive shaft enters the differential? Where would you start looking?

This looks like a leaky pinion seal to me. The diff oil is probably seeping out into the drive shaft, which is flinging it around as it spins; the wind is pushing those droplets back as you drive, so the oil is going to be aft of the source of the leak. At lower speeds, that drive shaft is still going to fling oil around and the turbulent air under the truck will have eddies and swirls that result in oil on the back side of things.

The best bet is to A) check your diff fluid level and ensure it's fully topped up
B) make sure your breather isn't clogged with dust, that can pressurize the diff when it gets hot and push fluid past the seals
C) degrease everything really, really well; pay special attention to the pinion seal area.
Then go for a short drive and re inspect it for oil.

 

[jac04]

Just be careful with any type of degreaser. Remember that a leak path may also be a path back into the diff. So, I would used shop towels dampened with your choise of degreaser to clean up around the pinion area. IMO, avoid spraying the area with a 'spray-on' or 'spray-on & wash-off' degreaser.

 

[Sweetums]

That's probably less of an issue, a hot diff will have positive pressure and if the seal is bad you are going to have to drain the diff and replace the seal anyway. If the seal is good then the degreaser won't get inside anyway.

 

[ShadowsPapa]

I've never had an issue with all of the transmissions and differentials I've cleaned for leak checking. I've pressure washed them, used brake cleaner, mineral spirits, almost everything.
And yeah, if there's a leak, you are going to take things apart anyway.
Unless there is huge obvious damage to a seal, nothing is going to get past it unless you aim some heavy pressure at it.
You would have to aim directly at the leak area with some pressure to get in - leaks happen over time, and a quick cleaning doesn't give enough time for something to push past the outgoing gear lube and get in.
No worries.

 

[WILDHOBO]

My money is on pinion seal .. pinion seal is easy to fix but you want to make sure and torque the pinion nut back down correctly after replacing the seal and reinstalling the yoke and pinion nut . There are several videos on you tube showing this procedure . With torque values included.

I’d agree based on having had a few of them leak on me. Coincidentally, I’ve discovered a super recent front diff pinion seal leak. Super slow and no flinging, but I need to fix it. Care to elaborate on it being easy? Do I need to remove everything in the diff, meaning all the gears? Obviously it needs to be drained. Is the seal replaced from the outside, or from the inside? Thanks. I’ll google things as well.

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