Driving with blown axle seal
 

Just got back from a big desert trip in my 4runner and while checking the suspension and brake lines and such under my truck I noticed a little bit of oil splatter on the inside of the rear passenger tire. The classic sign of a blown axle seal. I checked my breather and sure enough it was all but totally clogged with dust, I could barely blow any air through it. Because of this, and the fact that there is zero slop in the rear wheels, I think it's safe to assume this was the cause and not a bad wheel bearing. Plus, it was only a very small amount of oil, nothing near the pictures you see on here where the whole tire is coated. And, I didn't notice any brake fade so I might have even gotten lucky and didn't contaminate the pads somehow. However, I don't have the time to do the seal replacement until at least Sunday, so is it ok to drive on until then? If I hadn't given the undercarriage a visual check I probably wouldn't have noticed it for a long time, but now that I know I'd hate to be driving it knowingly causing damage. Any thought? Thanks!

PS. Huge thanks to BigFishAllDay, your write up on this is fantastic!

Will be fine. I drove months on mine leaking, hence leading me to have to replace the left rear wheel bearings. The lesson, the sooner fixed the less to be replaced.

Don't forget to get a new breather.

Mike, you need to do some more research before deciding just a seal replacement is going to solve your problem. I'll just quickly say what you may not know is Toyota redesigned the seal sometime in the past and now the seal lip will be sitting 2mm more inboard. If you just replace the seal and do nothing else, that seal lip will be riding very close to the non-polished bevel of the inner retainer. With a little play in the axle, the seal lip will be riding on the bevel sometimes and it will wear out prematurely and you'll be leaking all over again.

I would read through DrCoffee's thread on this subject for further info and you can watch the video @infamousRNR and I made for this repair.
http://www.toyota-4runner.org/3rd-ge...xle-seals.html

<iframe width="560" height="315" src="https://www.youtube.com/embed/AVhSDnw2ugo" frameborder="0" allowfullscreen></iframe>

Anyone know if non-oem Toyota seal are of the 'old' design that did not move the seal lip 2mm closer inbound?

Even if I get a new retainer ring pressed on, how will it not just have the same problem? Are you saying that Toyota changed the seal so that it won't work properly? I don't exactly have the cash to shell out on the full wheel bearing job right now, would it be possible to just replace the one retainer ring that the seal rests on? Also there shouldn't be any problem with just doing one side's seal right?

No, what I'm saying is that if you just replace the seal and do nothing else, the seal lip will be riding very close to the bevel of the inner retainer. Your bearings probably have a lot of miles on them and will allow some in and out play of the axle shaft. Because of that axle play, the seal lip will end up riding on the non-polished bevel part of the time. The bevel is not a polished surface and will prematurely wear out the seal.

A big reason why axle seals fail is due to worn out bearings that allow excessive movement in the axle shaft and thus extra strain on the axle seal. It's not just in and out movement but up and down movement as well. Over time, the old seal can't handle it and it fails. The new seal design is an improvement over the old design because it's more pliable and will handle more movement in the axle shaft.

If you're short on cash, your best bet is to replace the seal and reposition the inner retainer so the seal lip rides more near the center of the polished shoulder of the retainer. Some people keep the retainer in the original orientation, bevel facing the seal and just move it more inboard around 2mm (3mm of polished axle showing above the retainer). But, when you do this the inner retainer is now going to be coming very close to rubbing the inside of the axle housing. This is why I like the flipped orientation method. You get to keep the inner retainer in the same position as before on the axle (5mm of polished axle showing above the retainer).

Whether you do it yourself or have a shop do it for you, be very specific how you want them to press on the inner retainer. If you take it to a machine shop and they say they usually cut the parts off, I'd suggest you look for another shop. It's very common for shops to accidentally score the axle shafts by not being careful when cutting off the parts. The preferred method is to pull them off.

By repositioning the inner retainer and installing a new seal, you can buy yourself some time but ultimately you may have another failure because that worn out bearing is putting extra strain on the seal and it will eventually fail. This is why any shop is going to suggest you replace the bearing because it could very well be the cause of the seal failure in the first place.

Here's a visual representation so you understand better what I'm talking about. The first picture show the witness mark of where the original seal was riding on the inner retainer. The second picture shows the witness mark of where the new seal design was riding on the retainer. The person who did the replacement obviously just replaced the seal and didn't reposition the retainer. As you can see, the seal lip rides very close to the bevel which is not good. Ideally, you want to be riding somewhere near the middle of the 10mm polished surface of the retainer to allow for axle movement without compromising the seal.

I took this retainer off a guys rig that had a leaking axle seal. The previous owner or mechanic thought it was a simple fix of pulling the axle, replacing the seal and bolting it back up. People who do this end up with another leak much sooner than they'd hope and are confused and frustrated why the fix didn't work.

Here's some reasons why DIYers and Shops fail at this repair:

1) They're ignorant to the fact Toyota redesigned the seal
2) They didn't address the cause of the axle seal failure (clogged breather or worn out axle bearing)
3) They didn't press the parts on correctly, mainly the inner retainer
4) They didn't confirm they had a good mating of the seal and inner retainer by doing the very simple grease test.

Attachment 276213

Attachment 276214

yeah I've been driving on mine for quite a while now, think i should probably take it to the shop and get it fixed as well

Thanks for all the information MTBTIM.

I understand what you are saying, but I don't understand how replacing the bearing changes anything. Even with a new bearing, it looks to me like Toyota still designed the new seal wrong, as it would still sit close to the bevel without doing one of those tricks to fix it.

Also, it wouldn't be a problem to just to the bearing on the passenger side, right? That would obviously save a lot of money, at least until the left side seal blows.

edit: Ohhhh I think I get it now, I thought the retaining rings held the skid control rotor in place, and therefore had to be pressed right up against it. Is this not the case? If not then I completely understand it all now, you just have to not press the inner retainer onto the axle as far so it lines up better.
https://www.yotatech.com/forums/atta...tion-axle2.jpg