Leaky Side Seal - Front Diff

[_ExpeditionMan]

Hey Guys,

I have seen quite a few writeups on this for the 3rd and 4th gen guys, but as usual it seems a little thinner for the older trucks. I recently spotted a few drips under the 4Runner which I later identified as gear oil. The 4runner never spotted the driveway previously. The leak itself is coming from the passenger side of the front diff where the drive axle exits the diff before it mates with the CV. The leak is bad enough that I should change it before taking any other trips where 4x4 is required. Based on my research and the FSM it seems like there is an oil seal which sits just behind the drive axle which exits the diff. As usual the FSM specifies several SST be used during the replacement process, however I am hoping this is not necessary.

Have any you performed this repair? Any advice? I did the CVs about a year ago and it was a huge pain (I am planning on pressing out the studs this time to speed any future process). Anything else I should replace while I am in there?

 

[RonJR]

Basically you'll have to pull the CV to get it out of the way. Then the side-shaft is just held in by an internal c-clip, so just requires a good pry or slide hammer blow to pop it out. Once you have it out, you can pull the seal and drive in a new one, pretty much like any seal around a shaft.

Not conceptually hard, but it will likely fight you every step of the way.

Stop by Autozone and rent a seal puller and a seal driver kit. They'll give you a full refund when you return the tools.

The CV shafts spin whether or not you're using 4wd (unless you have manual hubs), so you need to fix it regardless of your use model.

 

[Bad_Vision]

Don't be afraid of this repair it's very easily done with minimal tools you'll probably need some metric sockets to remove the spindle and then a large socket for the CV shaft nut
[MENTION=134884]RonJR[/MENTION] is 100% right it probably will fight you because it's an old vehicle but even with that fighting you it shouldn't take more than an afternoon to do this project


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[_ExpeditionMan]

Basically you'll have to pull the CV to get it out of the way. Then the side-shaft is just held in by an internal c-clip, so just requires a good pry or slide hammer blow to pop it out. Once you have it out, you can pull the seal and drive in a new one, pretty much like any seal around a shaft.

Not conceptually hard, but it will likely fight you every step of the way.

Stop by Autozone and rent a seal puller and a seal driver kit. They'll give you a full refund when you return the tools.

The CV shafts spin whether or not you're using 4wd (unless you have manual hubs), so you need to fix it regardless of your use model.

Thanks for informative and helpful reply as usual RonJR. I will check out Autozone and luckily I converted to manual hubs when I did my CVs last. I responded to some of your other statements below.

Don't be afraid of this repair it's very easily done with minimal tools you'll probably need some metric sockets to remove the spindle and then a large socket for the CV shaft nut
[MENTION=134884]RonJR[/MENTION] is 100% right it probably will fight you because it's an old vehicle but even with that fighting you it shouldn't take more than an afternoon to do this project

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Thanks for the reply Bad_Vision. I have the tools necessary to change the CVs but the exploded view of the differential carrier is somewhat intimidating. While I am doing this I plan on changing both oil seals since if one blew the other is probably on the way out.

The only part I cannot wrap my mind around (and RonJR mentioned it above) is how to undo the snap ring, pull out the side gear shaft, and then how to put the ring back on during the reinstall without having to pull the front diff. Is the c clip just retained within the diff and then when the side gear is pushed back in the clip pops into place? Additionally, is removing the drivers side as hairy as it seems since it utilizes a lot of other parts?

Thanks for the information guys, I really appreciate the knowledge transfer.

 

[RonJR]

You don't have to physically remove the snap ring (c-clip) from inside. With enough extraction force on the shaft, it will just compress and pull out through shaft opening. Takes a good hefty pry with a big screw driver or a good smack with a slide hammer. (One of the SST's referred to in the FSM is nothing more than a slide hammer).

To reinsert just line up the shaft and drive it back in with a heavy hammer and block of wood.

Edit: Just to be more clear, the c-clip stays with the shaft. It just compresses into the groove on the shaft to allow the shaft to slide out.

The driver's side is more complicated, because you have to pull off the ADD mechanism. You'll need a male Torx driver for your 3/8" ratchet to get that apart (they're really tight). If it's not leaking I'm not sure I'd mess with it. The two sides are completely independent - it won't be any harder to come back later and do that side if you eventually need to.

 

[Brutalguyracing]

What gen runner we talking about here


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[RonJR]

'94 3.0 5spd. It's in the OP's signature line.

 

[Bad_Vision]

You don't have to physically remove the snap ring (c-clip) from inside. With enough extraction force on the shaft, it will just compress and pull out through shaft opening. Takes a good hefty pry with a big screw driver or a good smack with a slide hammer. (One of the SST's referred to in the FSM is nothing more than a slide hammer).



To reinsert just line up the shaft and drive it back in with a heavy hammer and block of wood.



Edit: Just to be more clear, the c-clip stays with the shaft. It just compresses into the groove on the shaft to allow the shaft to slide out.



The driver's side is more complicated, because you have to pull off the ADD mechanism. You'll need a male Torx driver for your 3/8" ratchet to get that apart (they're really tight). If it's not leaking I'm not sure I'd mess with it. The two sides are completely independent - it won't be any harder to come back later and do that side if you eventually need to.

[MENTION=134884]RonJR[/MENTION] is correct.
Last one I did I yanked the shaft out using a ratcheting chain binder slow steady pull and it popped right out. Replaced the seal and smacked it back in. You won't need to pull apart the differential at all and you can fix both seals by just getting the half shafts out of the way.


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[_ExpeditionMan]

You don't have to physically remove the snap ring (c-clip) from inside. With enough extraction force on the shaft, it will just compress and pull out through shaft opening. Takes a good hefty pry with a big screw driver or a good smack with a slide hammer. (One of the SST's referred to in the FSM is nothing more than a slide hammer).

To reinsert just line up the shaft and drive it back in with a heavy hammer and block of wood.

Edit: Just to be more clear, the c-clip stays with the shaft. It just compresses into the groove on the shaft to allow the shaft to slide out.

The driver's side is more complicated, because you have to pull off the ADD mechanism. You'll need a male Torx driver for your 3/8" ratchet to get that apart (they're really tight). If it's not leaking I'm not sure I'd mess with it. The two sides are completely independent - it won't be any harder to come back later and do that side if you eventually need to.

Thanks for the added info [MENTION=134884]RonJR[/MENTION] that helped me visualize it. Well I suppose I may do the side that is leaking and see how much of a pain it is. If I am tired and angry after that I will just hold onto the parts for the other side! haha

[MENTION=134884]RonJR[/MENTION] is correct.
Last one I did I yanked the shaft out using a ratcheting chain binder slow steady pull and it popped right out. Replaced the seal and smacked it back in. You won't need to pull apart the differential at all and you can fix both seals by just getting the half shafts out of the way.


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Appreciate the input as well [MENTION=63714]Bad_Vision[/MENTION]. Glad to know I won't have to pull the diff.

Have either of you switched the studs for bolts on the flanges of side gear? I am debating pressing these out to speed this process up for next time and am having a difficult time coming up with the size for the bolts. I read on a yotatech thread that said they were M8x1.25 but was hoping one of you could confirm from personal experience.

 

[RonJR]

Have either of you switched the studs for bolts on the flanges of side gear? I am debating pressing these out to speed this process up for next time and am having a difficult time coming up with the size for the bolts. I read on a yotatech thread that said they were M8x1.25 but was hoping one of you could confirm from personal experience.

I pressed them out of the drive flanges, and then chucked them up in the drill press and took a bit of sandpaper to the ridges that made them press-fit. They slide in/out easily now.

If you swap them make sure you get grade 8 bolts. Just take one down to the local HW store if you want to match it.

 

[_ExpeditionMan]

I pressed them out of the drive flanges, and then chucked them up in the drill press and took a bit of sandpaper to the ridges that made them press-fit. They slide in/out easily now.

If you swap them make sure you get grade 8 bolts. Just take one down to the local HW store if you want to match it.

Heck if it is that easy I will just do that. I knew it was a common mod, but didn't know it was that simple. Thanks a lot!

 

[kc15842]

Whats the advantage of a nut and bolt vs the OEM stud? IMO the pressed in stud makes it easy to disassemble. I remove the nut with the impact without having to hold the bolt with a wrench.

 

[RonJR]

Whats the advantage of a nut and bolt vs the OEM stud? IMO the pressed in stud makes it easy to disassemble. I remove the nut with the impact without having to hold the bolt with a wrench.

Some people (me included) find it easier to work the CV axle out if the studs are out of the way. Some swear it can be done with the studs in place, but I've had no luck at all.

 

[_ExpeditionMan]

Whats the advantage of a nut and bolt vs the OEM stud? IMO the pressed in stud makes it easy to disassemble. I remove the nut with the impact without having to hold the bolt with a wrench.

Like [MENTION=134884]RonJR[/MENTION] said above, removing the CV with the studs in place is extremely difficult. I spent a lot of time on it that would have been completely unnecessary if they had been bolts to begin with.