Hey
So my 02 4Runner had a bent rear axle shaft, which I had replaced in February. This cost a small fortune, and I was bitterly disappointed to notice, some 3 weeks later, that there was diff lube dripping out of the drum. I took the vehicle back to the shop that did the job for me, and the replaced the seals and brake shoes. Two weeks later I see there's lube dripping from the damn drum *again*!!! I can take it back again, and I'm sure they'll replace the seal again, but now I'm wondering whether something else in there is damaged?

The damage to the axle shaft seems to have come from a side-on impact of some sort which put a small dent in the wheel arch bodywork, but it appears the brunt of the force went into the wheel itself, which in turn bent the axle shaft. Given that we've now had two seals in there and neither of them has worked, is it possible that something else got damaged? I've had a close look, and can't see anything obvious whilst it is all assembled. Or is it perhaps that the shop I had it at just don't know what they're doing and cocked something up when they put it back together?

Also, how hard is it really to take that sucker off and put it back? From what I understand it appears to be a question of whipping the brake shoes and line off, undoing the 4 bolts holding the hub on, and pulling the whole thing out? Re-assembly worries me a bit more though, as I can't find anything that says I won't need some kind of press to get the seals etc back on again?

 

The seal is eazy bearing is more difficult. Really to get the seal out you dont even need to even remove brake hardwear. all you need to do is remove the wheel, disconnect the ebrake line from back of drum, basically a cotter pin and a pin. then disconnect brake line. Remove 4 bolts and the whole unit comes out. Seal is right inside the axle housing right there. once you take the seal out throw a replacement in and reverse what was stated above. Bolts that hold axle shaft to axle housing are retorqued to 48ft lbs.

 

take it back and have the mechanic grease up the retainer and verify that the seal is even making contact with it. Also, insist on the OEM seal. He is probably assuming it is seated properly and it could be millimeters away from it.

Are you sure the axle was bent? Did he check it of just claim it.

 

So the axle was most definitely bent - that much I checked myself. From the sounds of things replacing the seal itself is not too much of a problem (I also just found a few well illustrated write-ups about it), so I might pull the axle again and fit a new seal myself.

However, one thing that did come up in some of the write-ups was the differential pressure relief valve which apparently gets blocked quite easily. Once this gets blocked and the diff heats up, the pressure inside forces itself out somewhere, and this somewhere is usually the axle seals. Why this would happen only on the left hand side probably has to do with something not being 100% kosher after the axle bending, but I do think I'm going to check up on this breather valve first before doing anything else.

 

if the bearing is shot it will drip right away no matter how much times you replace the seal,be sure to replace the axles bearings and seals with oem parts.seals are easy to do but for the bearings you need a press, and one more thing if youre going to replace the bearings yourself or take them to a shop don not hit them hard in place that will shot the bearings again.

 

How did you work this one out? I would have assumed that no gear oil should get past the seal, which is between the diff and the bearing, which means the bearing should never get gear oil on it, and so doesn't play a part in sealing the axle off.

 

when the truck moves the the diff gear moves the oil from bottom up so this way the gear and conical are always lubed and some of the will get to the axles housings reaching the bearings in small amounts if the diff is not overfilled,the bearings need to be lubed because they are not sealed ones when the bearings are shot you will see some play in them this is actually a bearing faillure even a little play can cause a leak drop by drop untill it pass the seal.remenber that the seal is not too hard because the axles need to move freely if you put a stronger seal it will burnout becuase of the friction with the axle,another thing with bearing failure is the bearing carrier itself with time is possible that the carrier shape change.trust me replace the bearings,bearings spacers and seals and your done.
my 4runner was suffering the same problemafter 2 pairs of seals i decided to replaced the bearings and the problem was fixed.

 

There are 3 seals for each axle shaft.

1. seals the gear lube from getting into your axle bearing. The bearing is sealed and gear oil should not contact it.

2. is a more of a dust seal. This is the one that you press into the axle housing itself.

3. is an o ring. it goes on the outside of the axle housing.

From my experience with these types of axle leaks (luckily not too much) there are only a few things to check:

With the truck in the air, check for any up/down movement by grabbing the wheel and trying to lift it. There should be no play.

Make sure your diff breather is not gummed/rusted/clogged.


The shop my be unaware of all the seals.

Also,he gear oil washes the grease out of the sealed bearing when it gets past the main seal too, so the bearing might have play in it and be casuing this leak.

 

I can attest to that. My Timken seals died in two days. They went from super snug to super loose.

This thread should help make sense of this repair

problem of and solution to leaking rear axle seals

 

have you checked to see if the axle housing itself isnt bent? Im no expert so this could not affect it but on my jeep i bent the rear axle and i put new shafts in it twice and new seals twice just to find it still leaked. Turns out it was the axle housing. Not sure if this has already been ruled out or not but i didnt see it on here so i figured id add it.

 

OP, did you finally fix the axle leak? Could you post back with how the story ended?

 

x2 on the bent housing. You probably can't see it but if it was hit hard enough to bend the shaft or flange(wear the wheel bolts to) then it is more than enough to bend the housing. The seal could be installed correctly but sit cocked on the shaft. Also you can't replace just the seal like "medic" said. Once the bearings are full of oil they will always seep oil. Do yourself a favor and save some money and buy a complete axle assembly. It will probably be cheaper labor wise than disassembling your bad axle and putting all the parts back on a unbent housing. Not to mention the bearings, collars, seals, brake shoes etc. are going to get expensive quick.