Leaking rear axle - inner or outer seal??

I just had my state inspection and the mechanic told me my rear drivers side axle seal was leaking, sure enough when I got home I looked under and the rear drivers brake drum and inside my wheel are coated with oil/grease/dirt. It's a mess, and I haven't taken the wheel and drum off to see what the shoes look like yet. I was just looking at my manual and it seems relatively easy to replace the outer seal, but is that the one that is leaking? I couldn't find anything about an inner seal? Any information and/or advice is appreciated, thank you ahead of time. Here are front and rear pictures of the drivers side rear axle:

 

There is also the possibility that your wheel cylinder is leaking, causing that mess. Just a possibility.
Other than that, both the inner and outer seals will require the removal of your axle shaft from the truck. It is not a difficult process, but you need to be prepared. The inner seal is the easiest to replace, as you simply remove the axle assembly, then replace the seal in the housing that the shaft slides into. The outer seal is more difficult, and you will need a good press, and the special tools required to do this. You may want to consider having it done at a shop that has the special tools. Some people have various "shade tree" methods of separating the shaft itself from the bearing assembly, and they may speak up to give you some insight.

 

Is there a way of knowing if it's the inner or outer seal that is bad? What is each one's purpose, in other words which one is sealing the gear oil? If it is the inner seal it seems like I could do that myself if I buy a seal puller and something big enough to drive the new one back in, or am I kidding myself? I'm a fair DIY mechanic, I managed to replace front struts and rear leaf springs on my own.

Second question, my truck has 183,000 miles on it. I'll be replacing the shoes when I do this rear seal, should I also replace the wheel cylinder while I'm doing it or should I just leave the old ones in?

 

If the wheel cylinders are not leaking, no need to waste the money. Wheel cylinders are easy to replace. As to which seal is leaking, when you remove the drum, you can look where the shaft enters the hub assembly. If you see oil there, then it is most likely the outer seal. Personally, if you are already in there, the best thing to do is replace both seals, just to be safe. the seals themselves are not that expensive.

 

Most likely the "INNER" seal that failed, far more common than an outer seal which is waaay more difficult to fix since you need to seperate the bearing assy from the axle shaft.

The inner seal is exposed once you pull the axle assy out, actually pretty easy to swap, just make sure to put a little bit of sealant on the outside of the seal as well so the oil doesnt leak on the outside! Also put a little bit of grease on the seal lip before assembly, and be careful when putting the axle back in so you dont damage the new seal.

I just did one 2 weeks ago, I have probably done 30 of them over the years., and only done an outside seal once.

 

Guess it depends on where you are located? I have done almost as many inner as I have outer seals on the Tacoma.

 

I would replace both. If the INNER seal fails and the OUTER seal is fine you will get gear oil inside the drum, and it will fling onto your rim. If both fail it will look like what you have. Note the outer seal is an O-Ring. I just had to replace my inners, took 15 min a side. Used two screws to get break drum off(for cleaning), and that took most of the time.

EDIT: The inner seal is used to keep the oil in the axle housing.
The outer seal is used to keep water and dirt from getting to the bearing that is pressed on to the axle shaft.(wrong) The o-ring is does this. Corrected by BamaToy1997

 

Thanks for the replies. I bought an inner seal and the o ring at Toyota, and bought new shoes as well. I've gotten the drums off, I thought that would be the hardest part but it wasn't bad at all. Sprayed it all down with brake cleaner but it's now nearly 100 F so I'm taking a break until tonight. I've been reading a bunch and I keep seeing that one possible cause of seal failure is the top vent gets plugged. Does this just unscrew from the diff? How do you check if it's plugged?

Also, the o ring isn't the outer seal, is it? My Hayes manual isn't very good at explaining it, it just says if the outer seal needs replacing take it to a shop. When I get everything back together, do I put sealant around the inner seal and also around the o ring? Is there anywhere that I should make especially sure does or doesn't get sealant?

 

Yes the breather just screws off the diff. You can blow through it to see if it works.

There is a seal for the bearing. It is a huge chunk of rubber, and looks funky. But you have to use a press to get to it. I think you have to press out the bearing.

I would not put sealant around those seals, make sure the inner seal goes in straight.

Just make sure you put some gear oil on the inner seal where the shaft rides, and do not let the truck sit after replacing the inner seal. They say to drive it a little befor you let it sit, kind of wear it in.

 

Thanks again. Oh yeah, Bama, your sig is hypnotizing, I could sit and stare at that blonde for an hour and not get bored.

 

You are incorrect sir. The o-ring seal is used to keep water from getting behind the hub where it bolts to the axle tube. However the outer seal is actually the seal that is in the hub assembly, and seals the shaft where it passes through the bearing. The inner seal is press fit into the tube and seals the shaft off so that the axle lubricant does not get into the bearing. The bearing is a self contained and self lubricated bearing. You don't want axle oil in this bearing, hence the need for the inner seal.
So if you want to get technical, there are 3 seals total per side.

You are getting sleeeeepy sir...you will now give all of your money and your Tacoma to meee!!

 

Crap. What seal is it then. I know what it does, just not the name, anymore.

 

Haha. I am not sure what the technical name is, but we call it the axle tube o-ring.

 

Ah, ok thanks!

 

I've got the new seal in, now I just have to get the old shoes off and the new ones on. It's near 100 again today, this is insane weather for my part of the country. I tried my best to make sure the axle went in without resting on the seal and damaging it, I'm assuming once I start driving it I'll know pretty quickly if the new seal is damaged or not? Also, I didn't put any sealant on the flange face, just put a little grease on it and around the o ring. The hayes manual didn't say anything about using a gasket or sealant, is this the right way to do it?

 

How bad was it to press in the seal? I haven't changed one on my truck yet, but I've already them go out three times under warranty. When I changed em on my Ranger I usually had a couple spares just in case, and I did, usually break them installing them.

How were your brake pads? Dealerships replace the brake pads if they're soaked in fluid.

 

Getting the old seal out was easy with my $7 seal puller, and putting the new one in was just a little harder. I used a chunk of 2x4 that covered the whole seal and hit that in until it was flush, and then used a smaller piece of plastic pipe that was the same diameter as the seal to fully seat things. The inner seal is pretty delicate, I was surprised how flimsy it seemed. My drivers side shoes are soaked and completely useless but they were old and going to be replaced soon anyhow. Assuming I actually did things right and the axle stops leaking it wasn't terribly difficult overall. As long as you have the right tools I'd guess it might take an hour to get the axle shaft out, repla e the seal, and put the shaft back in. The shoes are going to take me longer because they have a lot more parts to them than any drum brake vehicle I've had before.
Why did Toyota use drum brakes anyhow? Disk is so much simpler and easier...

 

Because Drum breaks wear less, and are cheaper to manufacture.

 

Soooo mesmerized... by.... sigg.......

 

wheel bearing will cause it to leak also man might wanna make sure there is no noise from that bearing