Front Differential leak

[IdahoDoug]

Is your axle vent clogged? The gear oil level shouldn't be up that high (and probably isn't) But it makes me wonder if as the diff heats in operation and pressurizes while oil is slung up that high it is coming out for that reason. These axles have a tendancy to plug their vents.

 

[landtank]

That is huge when Rick & Kevin are seeing eye-to-eye on a topic, and I’m glad Kevin vindicated my Permatex Grey thought / more than likely I bought Grey based on that for this job.

Thanks Kev - you’re still teaching

I've been running the stud kit with just a gasket without issues so far. When in MOAB that year and developing the leak I just tightenend down the nuts and it seemed OK but the gasket had shifted and torn so I pulled the diff when I got home.

But if the gasket is still in tact which means it hasn't moved out of place and possibly torn, I'd get a stud kit and follow the instructions for replacing them with the diff in place. I'm optomistic it will stop the nuts from loosening and eliminate the leak without the need to remove the diff.

 

[Broski]

I did not see it the first time I looked. But in post 1 & 20 you can see that the Gasket is spitting out. No amount on Tightening will fix that. JMHO
Time to pull the third and fix it right.

 

[landtank]

I did not see it the first time I looked. But in post 1 & 20 you can see that the Gasket is spitting out. No amount on Tightening will fix that. JMHO
Time to pull the third and fix it right.

yup, need to tear down the axle. The fasteners have failed and the diff has been shifting around and pushed the gasket out of place. I chose not to use FIPG on the last repair because it didn't really help the previous time I did it. I believe it's solely a fastener problem and the M8 class 8 hardware isn't up to the task.

Some have drilled and tapped and upgraded to M10 hardware with success, but I believe that moving up to M8 class 10.9 hardware is enough.

 

[inkpot]

I helped Kevin reseal a lot of diffs, and we have had good long term results using just SILICONE and the original studs with the nuts properly torqued. My P O had rehearsed my rig somewhere before 92,000 miles. Last winter around 210,000, the front diff gasket popped up very similar to the posted pic. I had checked torque periodically and never found any nuts loose. I run remote axle vents and they are clear, so I'm guessing maybe the gasket failure could be related to running 37s, or from TRYING to keep up with Kevin!

 

[Kernal]

Thanks for all the replies: excellent experienced based information.

Update: I couldn't see the top of the diff from under the vehicle
on my back in the driveway when I first just tried to tighten the nuts, so jacked up the vehicle yesterday, placed a jack stand under the right frame rail, then pulled the right front wheel and approached the front diff from there..

Once I got a closer look (and rechecked my own photos) it was apparent
that the gasket had pushed out along the top edge of the carrier flange.

I snapped off the gasket that had poked up, then cleaned up the area around the flange using some CRC electrical cleaner spray (doesn't seem to damage paint as much as Carb cleaner, no acetone?). Also removed the nut of the top right stud and cleaned the stud threads and around the base of stud well.

Then stuffed some Ultra Black FIPG (what I had on hand) into the seam where the gasket was missing (flange-axle housing) and then around the base of the stud, then replaced the lock washer and a flanged nut, torqued it down to 20 ft lbs and let it sit overnight for the FIPG cure.

Also tightened all the nuts again, this time with a torque wrench, to 20 ft lbs and maybe half of them moved a tiny bit (in hindsight maybe could have removed the nuts and applied Insensitive Blue thread locker to the studs, then retorqued, maybe bought me more time??).

Figuring this is a stop gap, might be able to delay the repair awhile before I have to do the whole front axle service (FAS) to pull the diff. Last time the FAS was done is unknown (one side may have been done about 5 years ago? by the PO) so had to do that anyways.

Here's some photos: Top photo is the piece of gasket that got pushed
out, note the partial hole far right for a top stud. Bottom photo shows the FIPG stuffed in the seam between the flange and housing and around the stud before tightening down the nut (moved the ABS line out of the way just for the photo).

I'll keep a close eye on it and post up more photos if (when) any leaks reoccur.

Also going to do the axle housing bypass mod once I can find more of the correct hose.

 

[ChaseTruck]

I like 'The Right Stuff' aka Permatex 85224 better for sealing the diff than the regular black silicone; it sets quicker.
However, it is also a PITA to remove a diff cover when the seal is still intact.

 

[landtank]

1. I've never seen a post of a leaking factory gasket that didn't have loose nuts holding the diff in place.
2. Using FIPG or similar when properly prepped will adhere to both surfaces.

Using FIPG is actually helping to hold the diff in place and acting like glue and in my opinion making up for the hardware.

 

[Kernal]

I pulled the front axle housing breather pipe while I was under the vehicle, it was clogged. So after cleaning it out decide to increase the ID of the pipe a bit as discussed by ?? many years ago.

With some turbine oil for lubrication I ran a 3/16 HS drill bit down the threaded side of the pipe assembly and a 5/32 bit down the more narrow pipe side to open it up where the two sections meet. After reinstalling the threaded pipe I connected a section of 3/16" hose up to the engine compartment, bypassing the stock breather assembly.

Plugged breather pipe assembly:

After cleaning, before drilling out:

After drilling to increase the ID:

 

[Sd1975]

Just wanted to add my 2 cents. Just did swivel hub rebuild because it was leaking. First time I drove it, noticed it was still leaking. Drove it for 2 days. Buddy of mine thought maybe breather tube might be clogged and sure enough, it was. Cleaned it thoroughly and leak stopped immediately. No more diff fluid dripping down from king pin area. If, after a hub rebuild, it's still leaking, check breathers.

 

[Broski]

FWIW, I think if you running big tire and like to wheel the axle housing is flexing and causing the third to loosen up. this happened to me several times.
After I trussed the axle housing it never happened again running 37s and how 39s JMHO
Of course if the breather is clogged and it's not coming out of the third it well just push past the axle seals

 

[80t0ylc]

Just wanted to add my 2 cents. Just did swivel hub rebuild because it was leaking. First time I drove it, noticed it was still leaking. Drove it for 2 days. Buddy of mine thought maybe breather tube might be clogged and sure enough, it was. Cleaned it thoroughly and leak stopped immediately. No more diff fluid dripping down from king pin area. If, after a hub rebuild, it's still leaking, check breathers.

Why not make it an essential step in your rebuild process? It doesn't take much time or effort and while you have it apart, that's the perfect time to do it. Also helps keep the seals from starting the leaking process from the build up of pressure.

Another tip: Don't just pull the hose off and blow through it and assume it's clear. Unscrew that fitting from the housing and verify that it's clear. You might even find, like I did, a wad of grease built up & blocking the hole in the housing. IMHO, this is where an axle vent is more likely to be plugged. You can't see this by just pulling the hose.

 

[landtank]

Since this popped up on my radar I’ll add that I’ve started using permatex hi-tack on all paper gaskets. Helps to hold them in place during assembly and adds some sealing as well

 

[LINUS]

Since this popped up on my radar I’ll add that I’ve started using permatex hi-tack on all paper gaskets. Helps to hold them in place during assembly and adds some sealing as well

That’s what I was taught & collected paychecks doing with teflon braided 1/4x2” gasket that is standard for vessel flange interfacing to whatever spool-piece & the access flanges - 24-36” sized circles.

We use good ol’ Weldwood, but we also buy it in 5gal buckets for those S/D events.

Small jobs just get 3M Super 77/88 on mineral paper.

 

[ZackR]

Thanks for all the replies: excellent experienced based information.

Update: I couldn't see the top of the diff from under the vehicle
on my back in the driveway when I first just tried to tighten the nuts, so jacked up the vehicle yesterday, placed a jack stand under the right frame rail, then pulled the right front wheel and approached the front diff from there..

Once I got a closer look (and rechecked my own photos) it was apparent
that the gasket had pushed out along the top edge of the carrier flange.

I snapped off the gasket that had poked up, then cleaned up the area around the flange using some CRC electrical cleaner spray (doesn't seem to damage paint as much as Carb cleaner, no acetone?). Also removed the nut of the top right stud and cleaned the stud threads and around the base of stud well.

Then stuffed some Ultra Black FIPG (what I had on hand) into the seam where the gasket was missing (flange-axle housing) and then around the base of the stud, then replaced the lock washer and a flanged nut, torqued it down to 20 ft lbs and let it sit overnight for the FIPG cure.

Also tightened all the nuts again, this time with a torque wrench, to 20 ft lbs and maybe half of them moved a tiny bit (in hindsight maybe could have removed the nuts and applied Insensitive Blue thread locker to the studs, then retorqued, maybe bought me more time??).

Figuring this is a stop gap, might be able to delay the repair awhile before I have to do the whole front axle service (FAS) to pull the diff. Last time the FAS was done is unknown (one side may have been done about 5 years ago? by the PO) so had to do that anyways.

Here's some photos: Top photo is the piece of gasket that got pushed
out, note the partial hole far right for a top stud. Bottom photo shows the FIPG stuffed in the seam between the flange and housing and around the stud before tightening down the nut (moved the ABS line out of the way just for the photo).

View attachment 2152052

View attachment 2152053

I'll keep a close eye on it and post up more photos if (when) any leaks reoccur.

Also going to do the axle housing bypass mod once I can find more of the correct hose.

@Kernal How's the temporary fix holding up? Mine is having this issue as well and still leaks after tightening all of the nuts to 20 ft/lb. I also pulled the breather and cleaned it out but didn't drill it as you did.

When I had the right front wheel removed yesterday I could see the gasket sticking up from the top but haven't messed with it yet.

 

[Kernal]

No leaks from the top of the differential-axle housing seam where the broken gasket pushed out and where the sealant was applied but 1-2 nuts (that were loose before) have seeped a tiny bit. IIRC I didn't apply sealant/FIPG to the nuts at the bottom that have a slight seep.

Key I think was the super-cleaning of the surface of the diff which was coated with 20 years of grease, oil, grime. I focused on the crack/seam where the gasket used to be and around the studs/nuts. Probably spent a couple of hours just cleaning, washing, cleaning, washing, degreasing, then using a small tool/pick to clean out the area where the old gasket was, more degreasing using CRC brake cleaner (the RED can which is TCE, no acetone so as not to remove all the paint), scrubbing with a small brush, etc,etc. As everyone knows everything takes 8 times longer when working on your back under a vehicle or twisted like a pretzel in a wheel well.

That 80 has had very few miles on it in the past year, but next summer I'll likely do a complete front axle service and drop the front diff to seal it up correctly.