Front Diff Scared me

[Bayrat]

When I do a change I remove the cover and flush it out. Generally, it isn't going to look or smell good. My dog somehow got into it when I was doing the motorhome axle and even with multiple baths and a haircut it was there for several months. I sometimes will flush a case if cover removal is too much of a PITA.

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[chevymitchell]

Thanks for the detailed explanation! Any idea why the fluid is so dark?

The fluid gets dark for many reasons. Mainly because of the black oxide coating that covers the ring and pinion. As the gears continually wear, this coating is eventually gone. The diff breathing through the vent tube allows the air from outside to get in and mix with the fluid. Dark diff fluid is normal. It will get cleaner, the more miles and fluid changes you do. The only time this won't happen is if you have the gears isotropically polished before install or you change the fluid more often than the recommended mileage. (Fluid will stay generally clean after the 3rd or 4th gear oil change.)

Most vehicles don't get gear oil changes but only twice in 100k miles.

Some of the heavier duty gear oil applications will go 500k miles+ (OTR Trucks)

This little bit of tailings and the fluid being dark is to be expected. No worries.

If you submerse your axle in water, then a fluid change or diff inspection would be wise. If the vent is plugged, the diff will breathe through the tube seals or pinion seal.

 

[Upnarms]

Curious why it was still dirty on second change?

Because it's used.

 

[Sparty]

No judgement here but not my thing

kind of a crappy POV

 

[MonsterTofu]

The fluid gets dark for many reasons. Mainly because of the black oxide coating that covers the ring and pinion. As the gears continually wear, this coating is eventually gone. The diff breathing through the vent tube allows the air from outside to get in and mix with the fluid. Dark diff fluid is normal. It will get cleaner, the more miles and fluid changes you do. The only time this won't happen is if you have the gears isotropically polished before install or you change the fluid more often than the recommended mileage. (Fluid will stay generally clean after the 3rd or 4th gear oil change.)

Most vehicles don't get gear oil changes but only twice in 100k miles.

Some of the heavier duty gear oil applications will go 500k miles+ (OTR Trucks)

This little bit of tailings and the fluid being dark is to be expected. No worries.

If you submerse your axle in water, then a fluid change or diff inspection would be wise. If the vent is plugged, the diff will breathe through the tube seals or pinion seal.

I know this is an older post, but I'm a bit concerned with my 22 JLUR Xtreme Recon's diff fluid. I had a slight leak in the rear diff area (dealer says its from the drain plug, but oil residue can be seen all the way to the driveshaft.) and my vehicle has been in 2WD most of the time. Now at around 28k miles, my Jeep starts to develop a clacking sound on colder and humid/rainy days and it'll clunk when coming to or taking off from a stop. Also a whirring sound can be heard from 45mph+ and the sound can be manipulated by the gas pedal. Dealer says some Danas are just louder, but this is driving me nuts, I checked my brakes, everything is fine, no misalignment or glazing. Could the diff be the culprit? Please advise

 

[MonsterTofu]

I know this is an older post, but I'm a bit concerned with my 22 JLUR Xtreme Recon's diff fluid. I had a slight leak in the rear diff area (dealer says its from the drain plug, but oil residue can be seen all the way to the driveshaft.) and my vehicle has been in 2WD most of the time. Now at around 28k miles, my Jeep starts to occasionally develop a clacking sound on colder and humid/rainy days when reversing or turning. It'll clunk when coming to or taking off from a stop. Also a whirring sound can be heard from 45mph+ and the sound can be manipulated by the gas pedal. Dealer says some Danas are just louder, but this is driving me nuts, I checked my brakes, everything is fine, no misalignment or glazing. Could the diff be the culprit? Please advise

 

[roaniecowpony]

Check the axle oil level.

If you had a leak from the axle drain plug it should have a distinctive strong smell of sulphur which gear oil contains. There's no mistaking it for anything else. You should smell it just getting close to the Jeep.
Once you confirm it's gear oil if the source is not obvious clean the area with a degreaser like simple green or Dawn in a pressure washer or go to a self service car wash with a pump bottle of degreaser. Once it's clean it'll be easier to spot the source of the leak. Then get to the dealer before it migrates around where the source is not obvious again.

If its coming from the pinion seal and making clunking and whirring noises it could be a loose pinion. If that is the case it will get worse until it fails completely. Be mindful of your warranty period expiring. The dealer may keep putting your concern off until you are past it.

Before your warranty expires get the dealer to write up your concern. "Customer complains of rear axle noise and leaking". Get a copy of their service write-up with the date and mileage. Once your warranty expires this will be important to prove you had the issue within warranty. If your dealer is uncooperative in writing it up this way seek another dealer or get an independent shop to write it up with an estimate.

 

[Upnarms]

Go to a reputable shop and get another opinion. Preferably a place that does gears, drive shafts, etc.

 

[jeepingib]

Check the axle oil level.

If you had a leak from the axle drain plug it should have a distinctive strong smell of sulphur which gear oil contains. There's no mistaking it for anything else. You should smell it just getting close to the Jeep.
Once you confirm it's gear oil if the source is not obvious clean the area with a degreaser like simple green or Dawn in a pressure washer or go to a self service car wash with a pump bottle of degreaser. Once it's clean it'll be easier to spot the source of the leak. Then get to the dealer before it migrates around where the source is not obvious again.

If its coming from the pinion seal and making clunking and whirring noises it could be a loose pinion. If that is the case it will get worse until it fails completely. Be mindful of your warranty period expiring. The dealer may keep putting your concern off until you are past it.

Before your warranty expires get the dealer to write up your concern. "Customer complains of rear axle noise and leaking". Get a copy of their service write-up with the date and mileage. Once your warranty expires this will be important to prove you had the issue within warranty. If your dealer is uncooperative in writing it up this way seek another dealer or get an independent shop to write it up with an estimate.

This is good advice. What @MonsterTofu has described could be the beginning of a failure in the diff by his description. So I definitely wouldn't just let it go because the dealer said that it was okay. Go to another dealership if you can.

 

[BobW]

Check the axle oil level.

If you had a leak from the axle drain plug it should have a distinctive strong smell of sulphur which gear oil contains. There's no mistaking it for anything else. You should smell it just getting close to the Jeep.
Once you confirm it's gear oil if the source is not obvious clean the area with a degreaser like simple green or Dawn in a pressure washer or go to a self service car wash with a pump bottle of degreaser. Once it's clean it'll be easier to spot the source of the leak. Then get to the dealer before it migrates around where the source is not obvious again.

If its coming from the pinion seal and making clunking and whirring noises it could be a loose pinion. If that is the case it will get worse until it fails completely. Be mindful of your warranty period expiring. The dealer may keep putting your concern off until you are past it.

Before your warranty expires get the dealer to write up your concern. "Customer complains of rear axle noise and leaking". Get a copy of their service write-up with the date and mileage. Once your warranty expires this will be important to prove you had the issue within warranty. If your dealer is uncooperative in writing it up this way seek another dealer or get an independent shop to write it up with an estimate.

A friend (who is in the German auto parts business) tells me the ultimate recourse is saying "ok, I'll talk with the Bureau of Automotive Repair".

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