2020 Rear differential leak @ 19K miles (1 Viewer)

[mbach]

I just noticed the leak yesterday.
There is a bit of a whine too which I'd discounted since I've pulled the seats but now I wonder.
This vehicle has been re-geared and has an e-locker.
It's under warranty with DSI but considering they jacked this vehicle up so bad in the first place I'm not sure where to take it.
The place that fixed all the other DSI issues is booked until 3rd week of September.
Would I be better off taking it to a gear specialist, the Toyota dealer or somewhere else?

 

[Tex68w]

Bummer.

 

[TimCFJ40]

Looks like a pinion seal leak, but with the whine I'd be concerned that the pinion bearing preload wasn't set correctly and that allowed the pinion to wobble and kill the seal. If that's the case, you'd likely want to have someone that's a diff gear specialist. Definitely not the dealer if you had new gears and lockers put in. That's the worst case. It's also possible that they damaged the pinion seal on install and nothing else is wrong, but the whine would concern me.

 

[TeCKis300]

^Agreed it looks like a pinion seal leak which requires tearing down the differential assembly which will affect clearances. Could be overfill, but as you have a whine, that suggests the pinion to diff ring pattern is not exactly right, requiring a tear down anyways.

 

[bloc]

Yep, preload not set correctly and the pinion is walking causing the whine as well as leak. And dealer will be useless, they’ll want to install an OEM chunk or possibly just tear it out and hand it to a gear shop, which in most cities is just 4wheel parts and is worse than doing it in your garage.

All of that said, shipping it off to someone competent is likely the quick way to get this done, and done right. I recall Zuk is taking a break but there are other shops that can properly set up gears before September. As it is you’ll need to work with someone that knows what they are doing to evaluate whether the gears have been damaged or can be reused.

 

[linuxgod]

If it's just the seal, which is what appears to be leaking, I think it can be replaced without tearing down the gears. Pretty sure you just pull the driveshaft, the 3rd member doesn't even come out. See attached.

Depending on how long you've had the gears, any whine may be due to low oil (if it's been dripping) and/or preload which is too low. It's entirely possible that replacing the seal, resetting the preload correctly (which is part of the procedure), and topping off the fluid will make the issue go away and your gears will be fine. Gear noise means something is wrong but doesn't necessarily mean your setup is shot. If it doesn't help the whine though then you're going to need to find a good gear shop. I don't know who is in your area but there are guys on the forum like @grinchy and @kreiten who live within a few hours of you and IIRC may have re-geared so you might ask around for a reputable shop.

 

[bloc]

If it's just the seal, which is what appears to be leaking, I think it can be replaced without tearing down the gears. Pretty sure you just pull the driveshaft, the 3rd member doesn't even come out. See attached.

Depending on how long you've had the gears, any whine may be due to low oil (if it's been dripping) and/or preload which is too low. It's entirely possible that replacing the seal, resetting the preload correctly (which is part of the procedure), and topping off the fluid will make the issue go away and your gears will be fine. Gear noise means something is wrong but doesn't necessarily mean your setup is shot. If it doesn't help the whine though then you're going to need to find a good gear shop. I don't know who is in your area but there are guys on the forum like @grinchy and @kreiten who live within a few hours of you and IIRC may have re-geared so you might ask around for a reputable shop.

The problem is if they set the pattern with the wrong preload, getting it right will negatively impact engagement.

Plus, the only procedure I know of to properly set preload requires only the pinion being installed in the case.

Now if we knew preload is correct, it is possible to change the seal and get the nut back to position without further crushing the collar (if they used one) but the whine and prematurely leaking seal causes me to question the whole job.

 

[linuxgod]

The problem is if they set the pattern with the wrong preload, getting it right will negatively impact engagement.

Plus, the only procedure I know of to properly set preload requires only the pinion being installed in the case.

Now if we knew preload is correct, it is possible to change the seal and get the nut back to position without further crushing the collar (if they used one) but the whine and prematurely leaking seal causes me to question the whole job.

yeah I’m no gear expert, just going off the FSM which mentions setting preload when replacing the seal. Hoping for the sake of the OP that replacing the seal and retightening everything will make the whine go away. If the pattern was correct (or close enough) and it took 19k to walk loose it’s possible it’ll be ok once it’s reset and refilled but I also wouldn’t be surprised if the noise persists

 

[TeCKis300]

If it's just the seal, which is what appears to be leaking, I think it can be replaced without tearing down the gears. Pretty sure you just pull the driveshaft, the 3rd member doesn't even come out. See attached.

Depending on how long you've had the gears, any whine may be due to low oil (if it's been dripping) and/or preload which is too low. It's entirely possible that replacing the seal, resetting the preload correctly (which is part of the procedure), and topping off the fluid will make the issue go away and your gears will be fine. Gear noise means something is wrong but doesn't necessarily mean your setup is shot. If it doesn't help the whine though then you're going to need to find a good gear shop. I don't know who is in your area but there are guys on the forum like @grinchy and @kreiten who live within a few hours of you and IIRC may have re-geared so you might ask around for a reputable shop.

This is a great point and could account for the totality of the problem. Might be worth a try.

The whine could be something to key on. @mbach , has the whine always there? Or has it developed more recently? Could indicate whether it's a gear pattern issue or low fluid issue.

 

[bloc]

yeah I’m no gear expert, just going off the FSM which mentions setting preload when replacing the seal. Hoping for the sake of the OP that replacing the seal and retightening everything will make the whine go away. If the pattern was correct (or close enough) and it took 19k to walk loose it’s possible it’ll be ok once it’s reset and refilled but I also wouldn’t be surprised if the noise persists

I’ll have a look at the procedure when I get home but I do know Zuk uses a very sensitive torque wrench to measure drag in the pinion bearings, and this can only be done with the ring gear and differential out of the case.

@mbach a key indicator here will be whether there is any movement in the pinion. If everything is fine, the bearings are pulling together against each other to the point that it takes a small amount of force to even turn the pinion shaft. That tension is what we are referring to as preload.

If you get under there and can move the flange the driveshaft is attached to side/side or up/down -at all- things are not healthy. If you have access to a dial indicator with magnetic base you can see very very small movements.

Movement can be caused by damaged bearings, loosening pinion nut, or it not being set up correctly in the first place. Inspecting the nut is easy, just remove the four bolts holding the driveshaft to the flange and see whether the staked spot on the nut is still within the notch on the pinion shaft. The other causes will involve more serious diagnostics.

Oh and those four nuts are tight.. 65ft-lbf. I often have to double up my combination wrenches to get them free. When you put it back together don’t leave them too loose and try to put the washers back where they were.

 

[mbach]

This is a great point and could account for the totality of the problem. Might be worth a try.

The whine could be something to key on. @mbach , has the whine always there? Or has it developed more recently? Could indicate whether it's a gear pattern issue or low fluid issue.

I'm not sure about how long but I noticed the sound after pulling the second row seats.

 

[Moby]

I've had good luck with Randy's ring and pinion. Not exactly close to you but maybe close enough.

 

[mbach]

Seal/Bearings need to be replaced.
No issues reported with pinion movement.
Taking a couple months to resolve.

 

[mbach]

Finally repaired...
Seal was crusty with material missing and purportedly an aftermarket. Thanks 4WP.

 

[linuxgod]

Thanks for the update. Sorry to read about your trouble but glad to hear it's resolved.

 

[CharlieS]

I wonder if that is the seal that Zuk throws out and uses the Toyota one?

Edit: it sounds like he mainly uses factory seals: "I rarely use the generic seals in the kits and that includes this kit....I keep a stock of factory seals."

 

[cr8r]

Glad this got resolved, just went through similar issues with my 4th gen 4Runner as well. To anyone else experiencing issues like this, I can highly recommend east coast gear supply (ECGS) in the NC area. Those dudes know their stuff and can get you sorted out.

 

[nor_cal_cyclist]

I just noticed the leak yesterday.
There is a bit of a whine too which I'd discounted since I've pulled the seats but now I wonder.
This vehicle has been re-geared and has an e-locker.
It's under warranty with DSI but considering they jacked this vehicle up so bad in the first place I'm not sure where to take it.
The place that fixed all the other DSI issues is booked until 3rd week of September.
Would I be better off taking it to a gear specialist, the Toyota dealer or somewhere else?

View attachment 3059679

View attachment 3059680

View attachment 3059681

DSI screwed up both my diffs when installing gears and ARB's - rear pinion seal and front axle seal were both mangled and leaked within 8k miles. Would have never let them work on my truck knowingly - they should stick to lifting Jeeps and bolt on bumpers!!!

 

[mbach]

DSI screwed up both my diffs when installing gears and ARB's - rear pinion seal and front axle seal were both mangled and leaked within 8k miles. Would have never let them work on my truck knowingly - they should stick to lifting Jeeps and bolt on bumpers!!!

I'm concerned about the front seals too.
The gear shop that repaired the LC said the seal was weird in that the rubber was brittle and missing the dust shield.
I also did not know 4WP rather the Toyota dealer was doing this work.
4WP has demonstrated gross negligence and one 4WP employees advised me not to bring it to their shop for warranty work due to quality of work that would be done...
What to do??

 

[turbo8]

Glad this got resolved, just went through similar issues with my 4th gen 4Runner as well. To anyone else experiencing issues like this, I can highly recommend east coast gear supply (ECGS) in the NC area. Those dudes know their stuff and can get you sorted out.

I have used ECGS in the past for my 4runner, they were pretty good.

When I did my regear for my LX, ECGS was not up to speed on the 200 series diffs. ECGS claimed my core from a LX470 wouldn't work and didn't have any 200 series cores. I went with Zuk for my LX regear, using the 470 core.

@Timmy65 recently made some videos at ECGS showing their process.

Toyota 8" Rear Differential Regear/Rebuild

Hey Dudes, If you are interested in learning how a pro does a regear / rebuild of one of our 8" rear diffs, this is your opportunity to learn the process. We flew out from California to North Carolina to film this video and a video of installing an Eaton locker in my front 7.5" clamshell diff...

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