Ever since I've bought my 4Runner (Junior in high-school - about 7 or 8 years ago) I have been experiencing recurring rear axle leaks despite numerous repairs including the bearings and seals. I've taken it to multiple shops so I'm not sure if some have lied to me or whether they did a poor installation. What I'd like someone to enlighten me about is what could be the culprit and how I can find out what is causing the leak. Since I've purchased the 4 runner I've done a lot of wrenching and feel comfortable digging into the repair myself. I realize this is largely a common problem and I've researched the issue but seeing as to how I've had it repaired numerous times I'm hoping someone can send me in the right direction to figuring out how I can diagnose and fix this myself. Oh, and I have breathers installed already.

Thanks!!

 

The simple answer is that the lip of the seal should ride in the middle of the spacer ring. With the axle shaft out of the housing, the parts all make sense. Careful measurement is the only way to do this right.

I did both of my rear seals years ago, and then at about 300,000 miles I replaced the wheel bearings (for the first time) as well as the seals/rings/etc. Been dry since.



Andreas

 

Thanks Andreas for your response. So the bearings shouldn't be the culprit however is there any noticeable way to discern whether it is leaking from there? Is there anything else that could be causing a leak other than the bearings or the seal?

 

I found a fairly comprehensive post on the matter that answers my question. I should have searched more thoroughly. Thanks.

http://www.toyota-4runner.org/3rd-gen-t4rs/67299-rear-axle-seals-ultimate-information-replacement-thread-3rd-gen.html

 

Make sure to change the breather as well once the seals are replaced.

 

This!! Pressure is gonna find its way out somewhere. It'll blow past the seal if breather is plugged.

 

Hey man, I've had the exact same problem ever since I bought my 99. The inner seal makes a seal with a ring on the axle shaft. You might need that ring replaced as I did. Heat that sucker up and take it off. I had to then put the new ring in the oven to expand and you should be able to just drop it on. Ring onto the shaft. Make sure your breather isn't plugged too. Make sure your new seals are good. The outer seal doesn't do a whole lot as it is mostly a dust protector. I replaced my seals more than once before taking the shaft out and replacing the ring. Hopefully that helps!

 

https://www.yotatech.com/forums/f2/p...-seals-253319/

 

Thanks so much guys – A lot of useful information!

 

Would you happen to have a part # for that?

 

I believe I found it, if the "ring" is the retainer: 42423-20010 So what you're saying is that if I heat up this retainer (with a torch or something) it should slide off of the axle? Also, it seems the retainer would be riding on the rubber seal...would this really wear it out? I'm not second guessing you, just trying to understand. Thanks!

 

Yeah that's how I took mine off. Be really careful doing this tho, don't knick up your axle or anything. I'm not sure I totally understand your question, but that ring is there because the seal needs a smooth surface to form a complete seal. It needs to be there and is designed to be there. So no it shouldn't wear out. I hope that answers your question. I've attached the a pic of the ring that I'm talking about.

 

Make sure you ask your yota dealership before you start anything though, I don't wanna tell you to rip your axle out if what I'm talking about isn't your problem!

 

The ring was my source of error, but another could be a bad bearing too. Might have to change the bearing, as if it is worn the axle will move in the seal causing a leak.

 

I gotcha. My question was whether the part (the retainer) actually experiences wear since all it touches is the rubber seal. I was just having a hard time imaging metal wearing away on rubber, thus my inquiry. What temp did you heat it up in the oven afterwards to get it back on?

 

Oh I see. Yah you're right it shouldn't. I know after I changed it the leak stopped. It's been about 10k now and there's been no leaks. It was kind of a last resort thing to change. I wasn't going to buy bearings because mine were solid. So I just took out the axle and had a look at things. And haha I have no idea what temp I heated it to. Just get it good and hot!

 

Alright thanks, I appreciate it!

 

I replaced these 'retainers' since I was pulling everything apart anyway to install new bearings. My factory retainers with 300,000+ miles were utterly smooth - no discernible wear or grooves.



Andreas

 

If you've had bearings replaced, it's very possible that the machine shop that installed them put everything back on the axle improperly. Almost all of the time, when you have multiple press-fit items (bearing, ABS sensor ring, sealing ring) going on a shaft, they all butt up against each other. You just have to get the order correct.

But in the case of the rear axle, there are air gaps between some of the components. I forget if there's a gap between the ABS sensor and the bearing, but there certainly is between the seal sleeve/ring and the rest. If the sealing sleeve is pressed all the way on, until it butts up to the sensor ring, then the seal will not be on it when it is installed, the seal will just mostly be hanging in air above the smaller axle shaft. And (ahem) do a poor job of sealing.

Let my quickly google around for some pics...

This is likely bad, not going to work - the seal ring is pressed all the way up against the ABS sensor ring:


This is more like it needs to be - there's a gap between the sensor ring and the seal ring:


Another thing to consider is that even if you fix the seal issue, you will also probably need to repack the wheel bearings with grease. They are not oiled by the gear oil in the diff, the seal normally keeps the oil away from them. It's possible for the oil leaking out to wash the grease out of the bearing, which will lead to a premature failure of the bearing after the lighter oil leaves it.

 

I know this is an old thread, but I've recently encountered a similar issue with leaking axle seals, and I figured I'd post my solution.

I installed an arbor shim (McMaster-Carr # 3088A478) in front of the seal (between seal and differential) so that the lip of the seal would ride on the correct part of the retainer. This method does not require removal and reinstallation of the retainer. I have had no leaks since.

The shims I used are 0.062" (1.57mm) thick, 2.75" OD, and 2.00" ID. Other thicknesses are available.