Clean up the old oil mess off the bottom of the transfer case and keep an eye on it. That does not look like a bad leak. But, I would remove the fill plug and verify the level is good. On level ground, gear oil should be right at the bottom of the threads of the fill plug hole or up to 5mm below. If it needs some, top it off with 75w-90 gear oil. Or better yet, drain out the old gear oil and pump in some fresh gear oil. I recommend using some new drain plug and fill plug washers. You can pick them up at your local Toyota dealership parts department.

By the way, you never showed a picture of your front and rear output shafts on your transfer case. That's what this thread is about. Did you look to see if gear oil is leaking under the companion flanges the driveshafts bolt to?

I dont have any real help on this, but if your looking at 4-500 in labor and maybe saving a few dollars by replacing seals, I would let shop supply seals. My reasoning is that most shops will not warranty jobs if they don't supply parts. Some will warranty their labor if can be proven their labor caused the issue or install work was faulty. However you can request that they use TOYOTA parts rather than aftermarket. One shop I used to deal with said they would only use dealer parts if owner supplied because people would bring in junk brand aftermarket.
New seals wont break the bank.

I wasn't sure since I haven't had a chance to look at the diagram so I had a trusted transmission shop look at it and they said the issue was the output shaft seal thru the front drive shaft. That being said I allowed them to do the work with their parts (requested OEM parts if available) and it was like $230. I'll be picking it up today and they said they'll let me drive it for a few weeks then recheck.

Should I have them just do the rear output shaft seal as well?
Trying to get all the work done before my appointment to get the underbody cleaned/POR15d/Fluid filmed lol

Well, for that price, I wouldn't do the rear unless it was also leaking. I don't think they price gouging you but labor at shops is expensive. I'm guessing their labor rate is somewhere around $150/hour and they are billing you somewhere around 1.5 hours labor for the job plus the price of the seal.

Can't say thanks enough for such a solid and thorough write up! I just ordered this seal and I'll be tackling this within the next few weeks. My 4Runner is my first car and it's slowly turning me into a "car guy". Write ups like this give me the confidence to do these kind of projects myself. Thanks man!

I'm doing this job tomorrow night.

I have been putting this off, and it's only getting worse. I have a 200 miles drive for an offroading trip in a few weeks. Figure might as well get it done while I have the skids off!

Hopefully everything goes smoothly. My truck has only been offroad a handful of times by me since I got it last year, so far everything has been super easy to work on!

Well looks like my front seal is going out too.


I think it's just my inner seal as it seems dry on the companion flang to shaft interface. Went to the dealership down the road and wouldn't you know it, the inner seal is the one they don't have in stock there right now so I'll have to wait till Friday. Only 8 bucks more to do it so I'm doing the outer seal too while I'm at it and also got the nut. I have to do an oil change anyway and this also gives me a good excuse to change my tcase oil so I know when it was last changed (it looks good right now but hey it's only 8 bucks to fill it up and I'm going to lose all the fluid one way or the other doing the seal). Might also retap my two skid nuts that are stripped while I'm in there too. Also get the feeling that this is all a result of the breather being clogged. I was just in there too doing a short throw shifter upgrade and everything was crusty on top where my shift knobs were. I cleaned off the transmission shifter seat but not the tcase one ><

Good tips in this writeup. Have most people had good luck with that seal going in by hand? Seems like the rear seal doesn't but the two aren't the same seal either. As to the nut not needing to be unstaked to hit it with an impact, this actually makes perfect sense that this works without buggering the threads on the output shaft, the nut is obviously made of a very soft metal while the shaft is hardened steel. If anything unstaking it probably has a greater chance to damage the threads as then you are potentially introducing a shard that get's compressed in there trying to get the nut off. I plan on just hitting it with my impact.

Correct it's the inner seal as you can see the gear grease is all on the case..

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