Rear end seals - inner vs outer. Which leaks?

[92Pony]

So I'm working on my son's '98 limited 4wd(235k mi). Short story long - I had the Dr-side wheel bearing replaced due to noise. Gear oil had also leaked onto brakes necessitating shoe replacement. Before replacing the brakes, I thought it'd be wise to replace the seal on the other side, and have that bearing replaced while the axle was out (as the shop said there was a little bit of play in that bearing also - just not as bad as the dr-side).

I pulled the axle and dropped it at the shop for bearing R&R. I bought a Toyota axle housing seal and replaced it; which was a lot easier than I thought. I got the axle back, put it all together, and the next day had gear oil on my new brakes and on the wheel (side that I replaced). :moping:


Now for the question; Which seal is it that is at fault here? Is it the job of that inner housing seal to keep ALL of the gear oil in, or does the outer seal also serve in that capacity? Looking last night, it looked as though the oil was leaking around the under side of the hub where it comes through the backing plate (if that makes sense). Trying to determine if my install is at fault or the shop's - Fro the record, I'm banking on it being me. :dizzy:


Unfortunately, I'm getting pretty good at pulling an axle. My son and I pulled it back out last night (in about 20min) and I installed a new (non-Toyota) seal. This is one that I got from the shop that did the dr-side repair. The truck was driven to school today, so I'll know later today whether we were successful on our 2nd try or not.

 

[3bears]

thye both do the job if installed correctly

the inner seal is supposed to stop the oil from getting to the bearing. the ring behind the bearing, furthest from wheel has a critical placement measurent or the seal will not seal on it
the bearing is a sealed bearing
the outer seal is to stop oil from going out, but also dust from going in.
if you get oil out, then the first (inner ) seal has been leaking for some time and pushed its way through the sealed bearing as well

a Toyota man I know with 40 years dealer experience said the majority of the axel seal failures is caused by a plugged breather on the diff. the diff builds pressure, from churning hot oil, cant breathe and pushes out the seals
so check your breather, they can be cleaned, or replaced or you can do the breather mod

 

[92Pony]

Once I realized that it was leaking (and not just some residual), I checked the breather. It was caked on the outside with mud. I pulled it out and was able to blow through it. I cleaned it off and blasted some brake cleaner through it too, so at this point, it should not be a contributor.

That ring you mention (I've also seen it called a retainer, assuming we're talking about the same thing) should indeed be in the correct place. After watching a YT vid where a guy had a shop put his on wrong, I paid careful attention to that and questioned the mechanic at the shop who pressed mine on. He located it according to Toyota spec - just as he did the dr-side which is not leaking after his work there.

 

[JRZEE2000TR4LTD]

No need to keep replacing seals, unless they look pushed outward or damaged in some way. I copied this from one of my previous posts:
Make sure you do the grease test to verify the position of the inner retainer, which is what the seal rides on and is CRITICAL to a proper repair.
Just smear a little grease on the inner retainer, and carefully insert the axle asy completely back into position. Might have to tighten down a couple nuts to get the asy completely on. Then remove the asy and look at the grease on the inner retainer hopefully half the retainer is clean. Probably have a couple mm tolerance in either direction from center of the retainer.

The outer "oring" serves as more of a dust inhibitor than anything. I reused mine the 1st time I did this repair.

3bears is right about the oil pushing through the bearing and the dif breather. The bearings come pre greased so get it all fixed quickly or else you'll wash out your new bearing with gear oil.

 

[JRZEE2000TR4LTD]

Once I realized that it was leaking (and not just some residual), I checked the breather. It was caked on the outside with mud. I pulled it out and was able to blow through it. I cleaned it off and blasted some brake cleaner through it too, so at this point, it should not be a contributor.

That ring you mention (I've also seen it called a retainer, assuming we're talking about the same thing) should indeed be in the correct place. After watching a YT vid where a guy had a shop put his on wrong, I paid careful attention to that and questioned the mechanic at the shop who pressed mine on. He located it according to Toyota spec - just as he did the dr-side which is not leaking after his work there.

It shouldn't be leaking then. The ONLY way it can leak is either by improper placement of the retainer, grooving (by cutting the retainer of with a cut-off tool) the axle where the retainer rests creating a gulley for the gear oil to leak under the retainer, or by damaging the seal when inserting the axle asy into place.

 

[92Pony]

It shouldn't be leaking then. The ONLY way it can leak is either by improper placement of the retainer, grooving (by cutting the retainer of with a cut-off tool) the axle where the retainer rests creating a gulley for the gear oil to leak under the retainer, or by damaging the seal when inserting the axle asy into place.

When I got the axle back and inspected it, I saw no grooves or other damage from the retainer being cut off. (The old retainer was pressed so far down, I don't know how it was sealing at all.) The newly installed retainer is now installed on a portion of the axle that was visible before, so I know there was no damage under where the new one now sits.

My only thought is that when we initially reinstalled the axle - I let my son (16yr-old) slide it in with my assistance - he let the axle rest by itself on the housing for a few seconds when we were about an inch or two from the axle being 'home'. *Maybe* that could have hurt the inner seal the first time? This time around, I slid it in doing my very best to not let anything touch that dang seal until the backing plate hit home to the housing. We shall see.

If it leaks today, I'm taking the whole truck to the shop to let them see if they can get it right! (Plus, they can verify the correct placement of the retainer that they put on - I'm actually fairly confident that they have that right though.)

 

[3bears]

Its another reason people don't reuse retainers all the time. sometimes they can have a slight belly in them form where the last seal rode for 100k plus miles, or so Ive been told,
but yes placement is everything
good luck, let us know how it goes

 

[92Pony]

I just got a call from my son. He got home from school, took a look and said it's leaking again. :mad2::rockthrow::cry2:

I'm taking it to the shop in the am. Maybe they can fix it - I'm ready to burn this truck to the ground right now..... :noidea:

 

[3bears]

I hope its a good shop whom has worked on these rigs before

2nd, that they warranty it parts and labor for a year

good luck

 

[St Runner]

I went through this when i fixed mine. It seems simple but not a lot of room for error. Make sure you use a toyota seal, they redesigned it and the aftermarket ones still use the old design. As JRZE said do the grease test, there are two different positions for the seal retainer to be depending on wether you have ABS or not. Make sure the shop knows this as they are setting the retainer. Buy a new breather for the diff, they are cheap and now you don't have to worry about it.
Check where the inner seal sits and make sure there are no gouges in the axle housing from overzealous pulling of the seal, if there are use a small amount of rtv to make sure no oil goes around the inner seal. Finally make sure you set the inner seal at the proper depth, the tolerance for where the inner seal rides on the retainer is small and that is where your problem probably is, The grease test will confirm this

 

[92Pony]

Update:

I just got a call from my son. He got home from school, took a look and said it's leaking again. :mad2::rockthrow::cry2:

I'm taking it to the shop in the am. Maybe they can fix it - I'm ready to burn this truck to the ground right now..... :noidea:

I decided to give an update/resolution to this thread (I hate when people don't do that).


When I got home and looked, there was some fluid that had leaked, but it wasn't a lot (not as much as he made it sound like). We pulled the rim/tire, cleaned the drum, shoes and all other surfaces, including the back/inside of the rim. I had a thought (hope) that maybe, just maybe, we were dealing with some residual fluid that hadn't gotten cleaned out from the leaking first replacement seal.

He came home the next day and there was a tiny, tiny bit of leak visible on the rim. We pulled the tire and drum and cleaned everything again (I should have bought stock in brake cleaner before starting this job!). I sent him on a 25min drive and when he returned, everything looked dry. The following day, he drove about 100 miles, and when he got home, I checked inside the rear wheel - DUST! YES! No gear oil - just dirt road dust!

I believe we somehow damaged the first replacement seal and it leaked. The second seal and axle installation was successful, only yielding some residual gear oil seepage for a couple of days afterward.

Whew.

 

[owyheerat]

Thanks for posting an update. I am planning on replacing my inner and outer seals this winter. I found this thread helpful.

Durwin

 

[3bears]

glad its fixed