Rear Differential Leak (Axle Seal Revisited)

[cherrybomb]

Hello All,

So, I've been having some pretty bad luck with my rear axle lately.

First, I thought that my diff was leaking from the axle seals. (See here). So I replaced them, while I was rebuilding my Trac-Lok. (See here).

Unfortunately it was still leaking, but evidently not from the axle seals. So I replaced the pinion seal (See here). But now, it is leaking again. This time, for SURE from the drivers side axle seal, as I can see oil on the inside of my wheels.

So, I'm going to go at this again, and replace the bearing/seal probably on both sides of the axle. Any idea why this may have failed so quickly?

I'll admit to having used "just any old" bearing I got from a local Car Quest, but they seemed reasonably good.

Any suggestions on a better brand to buy? (I'm considering getting the bearing/seal set from Ford Racing)

I didn't have a bearing install tool, so I tapped things in with a hammer around the edge, maybe I damaged the seal? It looked fine when I was done. Any suggestions on an installation method?

Thanks in advance, hoping to only do this once more. Planning on installing a temp gauge as well.

 

[IZwack]

Strange that you're blowing so many seals - Is the breather on the axle okay? It seems that its clogged or something.

Its been a while since I last looked at an 8.8 axle so I don't exactly remember where the breather tube is - but hey usually its on top But anyways, I would remove the differential cover and, again I'm not sure where the breather exactly is so if needed, I would also remove the carrier (keep track of which bearing cap goes where if you do this). Then blow down the breather tube with your mouth and feel if there's any air coming out of the hole in the differential's housing.

Also, when driving in the seals, make sure they go in square - not lopsided.

EDIT, I just noticed that the breather is on the axle tube itself so forget what I said about removing the carrier. Instead, I would use a small metal rod and stick it down that hole to ensure its not plugged. And since you're going to replace your differential cover anyway (as you mentioned in your other thread), you might as well drill a tiny tiny hole on the very top of it For good measure.

And BTW, what gear oil are you putting in the differential?

 

[cherrybomb]

Strange that you're blowing so many seals - Is the breather on the axle okay? It seems that its clogged or something.

Its been a while since I last looked at an 8.8 axle so I don't exactly remember where the breather tube is - but hey usually its on top But anyways, I would remove the differential cover and, again I'm not sure where the breather exactly is so if needed, I would also remove the carrier (keep track of which bearing cap goes where if you do this). Then blow down the breather tube with your mouth and feel if there's any air coming out of the hole in the differential's housing.

Also, when driving in the seals, make sure they go in square - not lopsided.

EDIT, I just noticed that the breather is on the axle tube itself so forget what I said about removing the carrier. Instead, I would use a small metal rod and stick it down that hole to ensure its not plugged. And since you're going to replace your differential cover anyway (as you mentioned in your other thread), you might as well drill a tiny tiny hole on the very top of it For good measure.

And BTW, what gear oil are you putting in the differential?

Hey Thanks IZ,

The tube is clear, I actually checked that last time I was diagnosing this. Also, I've already replaced the cover. Thanks for the suggestions. I'll double check the breather.

I'm also confused as to why the seals keep blowin out. Thats why I'm going to install a temp gauge this time around.

I am using Mobile1 75/140. I've been skipping adding the friction modifier. Might add it this time around though.

 

[IZwack]

Dont fork your money on the Mobil1 until you have the issue solved. Just go with one of the cheaper brands. Once the axle stops blowing seals for lets say a thousand miles, then you can refill with the fancy shmancy oil

 

[mittelmeier]

The first time when you replaced the seals and the bearings were the bearings on the drivers side bad? And if so for how long. The axle shaft itself may have worn thin where the seal rides. This is common a problem on vehicles that repeatedly blow asle seals on the same side. If you don't want to spend the money on a new axle shaft they may have an axle seal relocation kit that moves the seal an inch or so one way or another on the axle shaft. If you have a micrometer you could check and make sure the area on the shaft isn't a little smaller than they rest of it but it's better if you have a new shaft to check it against. Hope this helps.

 

[cherrybomb]

The first time when you replaced the seals and the bearings were the bearings on the drivers side bad? And if so for how long. The axle shaft itself may have worn thin where the seal rides. This is common a problem on vehicles that repeatedly blow asle seals on the same side. If you don't want to spend the money on a new axle shaft they may have an axle seal relocation kit that moves the seal an inch or so one way or another on the axle shaft. If you have a micrometer you could check and make sure the area on the shaft isn't a little smaller than they rest of it but it's better if you have a new shaft to check it against. Hope this helps.

Heya, thanks for this!

Actually, when I replaced them the first time, the bearings, and seals seemed fine. I had assumed they were leaking, because I could detect the smell of gear oil, and figured it must be coming from those seals.

Now that you mention it though, when I replaced the bearing/seal, the new one I got was a single unit that had the bearing and seals all in a single bearing race. I wasn't able to drive this assembly in far enough for it to be flush with the axle housing. Perhaps this is the problem.

I do have a set of calipers, and I can check the overall size of the axle, but you may have just explained why I have the problem.

 

[cherrybomb]

Okay, the final verdict...

I had gotten the wrong part from the local car parts place when I replaced them the first time. Below are a few pictures comparing them to the RIGHT part.

I've replaced them, and they're no longer leaking. Turns out I didn't need to replace them the first time, since it was actually my pinion seal leaking. ARRG!

Long story short, my rear axle is all sealed up and no longer leaking. At long last!

bearing-width by qwikrex, on Flickr

axle-side by qwikrex, on Flickr

seal-side by qwikrex, on Flickr

 

[Doug]

I feel your pain. I resealed my rear diff on my SD twice (with expensive oil :\) until I figured out that I needed a new rear diff cover.