Time to play one of our favorite games: "Where's the leak coming from?"

What say you fellow old truck owners?


Obvious answer is rear carrier gasket, right? But maybe I'll get lucky and it is the pinion gasket? Worst case I have some major rust pinholes up top? But I think that last scenario usually happens on the rear cover, right? Somehow the rear of the diff actually looks pretty good.

As you can see, I've made sure the whole thing has a good layer of mud on it since I bought the thing this summer. It just got quite a bit cooler here last week when I noticed this, so I think a gasket shrunk on me and is crying out for replacement (just like my valve cover gaskets, sigh). And since it got cold, I have not felt like getting underneath and thoroughly inspecting things.

Anything else I'm missing?

 

Diff breather, maybe?

 

clean it up with a can of brake kleen and monitor

first guesses are pinion seal, rustholes , bad third gasket, or breather overflow as mentioned above not in any order but a cleaning and monitor will help.

 

doubt the breather would flow forward like that, unless you rerouted it above and forward and still it doesn't make sense you would fill the line with diff juice. Ditto for the brake line which is right above, won't drip forward while driving, but may drip downhill forward while parked. Also above that is fuel vapor lines, and charcoal vapor linnes, you would likely get a MIL for those if they had that much fluid and that much leakage.

Which really just leaves the driveline seals.

 

The diff breather is on the other side (to the right in OP's pic), so unlikely to leak in this pattern. The pinion seal would throw oil uniformly with the rotation of the pinion (look above) , so this stain pattern doesn't seem like that. I think therefore either the carrier gasket (unlikely) or rust (more likely).

Scrub off the dirt/debris all around, and de-grease with brake cleaner or other solvent. Then watch and wait...

 

Besides the leak, some of it on the top looks like grease flung from the zerks.

 

I thought that the rust pinholes are usually relegated to the rear cover, which is thin metal compared to the rest of the rear end?

I actually have been messing a lot with the EVAP system and get a consistent P0441 after a couple of drives. I've replaced the whole assembly back there but not the actual hoses. @10 blue trucks you might be onto something!

Gonna power wash the underside in the next couple of days and try to trace the leak as y'all suggest.

 

Well, there's that...

Maybe the sniff test is in order. Diff fluid smells noticeably different that gas.

 

Yeah so the other thing that makes this click is that I've gotten kind of random/vague fuel odor from seemingly that area at certain points in the past few months. Only started seeing this moisture last week though, and I haven't smelled much of anything recently. But whew that would be one of the better outcomes.

 

While you are under there, inspect the brakeline coupler up on the crossmember where it goes from hard line to flex line, and the other end of the flex line where it splits to the wheels.

 

Yup, will look at it all. First thing I checked is brake fluid level and it doesn't seem to have moved.

 

Yeah so it is definitely rust. GOOD GRIEF. Time to hunt for another differential. I'm sure finding a 4.10 rear end is going to be easy lol. Any point in going at this with a wire wheel and painting it with POR15 or something? I kind of don't like the idea of my diff being held together with paint. Probably worth it to spend a few hundred on a whole new diff? Maybe I can make myself feel better by finding a locker



At least my zerks work well:

 

wow thats a first i’ve seen where the front diff went bad. usually the rear is the problem

 

My rear cover looks great! No idea man.

 

1st gen Sequoias are 4.10, 3rd member is a direct swap.

 

All Sequoias? I mean, makes sense since the DC has so much Sequoia in it.

Found this list too:

2000-2003
3.91 - V8, 4x4, auto trans
3.92 - V8, 4x2, auto trans
4.08 - V6, 4x2, auto trans or manual trans
4.10 - V6, 4x4, manual trans
4.30 - V6, 4x4, auto trans

2004, Regular Cab or Access Cab
3.91 - V8, 4x4, auto trans
3.92 - V8, 4x2, auto trans
4.08 - V6, 4x2, auto trans or manual trans
4.10 - V6, 4x4, manual trans
4.30 - V6, 4x4, auto trans

2004, Double Cab
4.08 - V8, 4x2, auto trans
4.10 - V8, 4x4, auto trans

2005-2006
3.77 - V6, 4x2, auto trans
3.91 - V8, 4x4, auto trans
3.92 - V8, 4x2, auto trans
4.08 - V6, 4x2, manual trans

From: Also reading something about LC100 Land cruisers having 8.4 rear ends. Sure would be sweet to fit an e-locker from a cruiser, but I'm guessing that if I have not come across someone doing this, then there's more to it.

 

I think it may be all of them but I never actually checked, so ymmv.

The E-locker has a different 3rd member housing and flange. You would need to both grind out a notch and weld on an additional area IIRC.

 

If you can think of any info on that which is available on the internet, drop it here! Grinding I'll do but I think that I'd be drawing the line at welding, haha

 

More like a heavy duty grinder. A wire wheel won't make a dent in that and if it did, you'd be better buying a replacement differential because 1/2 the metal will have fallen off.

 

After seeing that 2nd pic, I guess the correct question is, "WHERE ISN'T THIS LEAKING FROM?!"

But, I mean .. yeah. That's gnarly. Time for something new!

 

Here's one, I think it might work. Check it out it before someone else snatches it!

https://www.japanesetruckdismantling.net/Toyota-Tacoma-Carrier-4-10-Ratio-p/41110-35750.htm

 

I think mine has the LSD option so I'd like to find one of those. There's probably a good dozen for around $400 on ebay but I haven't looked carefully enough to see if they have the limited slip or not.

So is the verdict that this isn't worth saving with a scrape and POR15? My rear end is smooth and quiet. Kind of a shame.

 

You'll only postpone the inevitable...(you may buy time to source the best carrier, and wait for warm weather to make the swap)

 

So the good news is that my diff is full…



Can y’all confirm that this is the limited slip innards?

Rear cover is alright although I’m not sure if I’d have gotten the fill plug out without some intermediate-level finessing with my impact.



Found a new diff down in VA. Guy was nice enough to agree to ship it up to me. This baby is gonna keep on rolling until the next part rusts out!

 

Good news on finding a new diff. Yes, that's the LSD. Darkness talks about the differences in the What's in your rear end thread. I can't seem to tag or link here, so do a search for that.

 

Thanks! I'll look for that.

Was looking at this earlier and it is packed with good info:

http://home.4x4wire.com/erik/diffs/#rear

Can't wait to change this dank fluid....

 

clean up the crusty bungs and squirt some penetrater on em. maybe hit them with some heat the day of cracking them open. do the fill hole first to be sure and then the drain last. golden -J.P.

 

Found that other thread too:

https://www.tundras.com/threads/whats-in-your-rear-end.42904/

 

Since you're going to have the carrier out (and therefore the axles out as well) it might be an excellent time to replace the rear cover!

$63 Dorman 926-958 Rear Differential Cover Compatible with Select Toyota Models (OE FIX)

https://www.amazon.com/dp/B07MFWBVF7

Then clean up the rear end, use rust converter and paint (POR-15, Eastman Rust Encapsulator, etc.) and it will last another 20 years!

 

Has the fluid ever been changed? Looks like mud water.