Looking for a "how to" - Front diff main housing seal replacement

Font diff main seal has a pretty unhealthy leak. Seems like it showed up outa nowhere. Guess that's how things can go. Gone today, here tomorrow....
This is uncharted territory, as I have not yet had to venture beyond cv axle seals/ecgs bushing.
I looked through the DIY sticky & did a search for a how to. I didn't see any tutorials, however I very well could have missed something.

Any ideas what I could use as a how to?
Also, please give advise, words of wisdom, etc.
Anything else I should/could address whilst in there?

 

Make sure your vent did not get filled with dirt.

Under pressure the fluid will push out the easiest place.

Many times just unclogging the vent will stop the leak.

Now if that is not the problem the reason why it failed needs figured out.

By Main seal you mean the pinon seal on the front differential??

They are changed just like the rear differential seal Without looking The torque numbers might be different

You might need to make a tool to hold the flange to break the pinon nut loose. My impact will just spin them off

I like having an extra pinon nut I have a habit of them running off with 10mm sockets

 

Can you pull back a little with the photo?

 

I put new breathers in last year & ran new line to the y bracket. I did not however, run line from the bracket to the dif & actuator.
If there is a culprit other than this main housing? seal, it’s coming from directly above it

 

I honestly cannot tell where the leak is. That's a lot of buildup so just looking at a picture makes it difficult. If you've never split the case, don't see why it would leak from there.

Directly above it would be where the breather tube is. Perhaps it's leaking there? You ran it to the bracket but not to the actual breather tube, the leak might be there.

Hate to say it but it probably is going to require pulling the diff to really understand what's going on and leaking.

Could also try cleaning it all up as much as possible with it on the truck and then periodically check/monitor. Might help with locating the source without removing the diff.

 

Here it is from the same view as the 1st. I flipped it the wrong way when I previously reposted as a pulled back view.
& the circled area is where it drips from. I have had leaking axle seals, so there’s a lot of hydraulic fluid gunky (mixed with wool wax, & engine oil) leftovers lurking. But this leak is definitely active. All I did was warm the truck up & there was an 8 in diameter puddle. Oh, & the drivers side (pictured) seal I finally got right, so that’s not at play here.

 

I think I wiped off the drips in between pics.
Here’s a zoomed in closer upper of the 1st
Same angle/view as 1st & 3rd pics

 

You warmed the truck up parked??

Nothing would be moving in the front differential

either trans fluid from a power steering leak or trans cooler line. or engine oil what is low??

 

Ok. Lemme try & get at the rest of the hose.

Apologies. I did move it out of the driveway, so I could get a friend's van in close enough to fill her tires.

It definitely smells like gear oil.

 

Is it possible you hit the front end or dropped it in a bad pothole ??

any strange noises coming from the front differential ??

things just don`t start leaking without some cause in most cases.


If not for bad luck you would not have any.

Just how low is the front differential on fluid?? Anything else low on fluid ?

Just what else has not been replaced or repaired yet??

 

You are my voices of reason. That's one reason I come here before I make most of my moves.

I'll start with cleaning it up & swapping out those hoses.

I am also just embarking on a total exhaust replacement, so driving it is not gong to be an option til at least friday as parts come in piecemeal. Only have one front cat to manifold bolt loose, so two more to go. Then I'm just cutting the rest off in pieces. & yes. I'll watch out for the gas tank.

 

No. No potholes or anything.
Hmmmm.... Strange noises. Just plagued by a whistling upon acceleration. Course the right axle seal is still plaguing me, so that could give a false reading on the gear oil level, as well as whistle (I believe).
I am keeping an eye on the oil cooler because I thought it looked a little greasy shiny, however I don't see any drips.
Not repaired? Tranny, Transfer case have had no changes.
Well, tranny mount has been done.
I just did the carrier bearing (just adding in case it may be pertinent).
I have not done any pinion seals.
I'll check fluid levels.

 

So much work going on... totally know that one right now. If you're working on those projects, might as well pull the diff and clean it up, replace your breather tube at the diff (not the bracket side). If its looking shady, crack the case and reseal it with fresh FIPG (Toyota #1281). Not sure how you can really get a good view of the portion of the diff with it mounted to the truck. I screwed up and installed the diff without attaching the breather line. I'm not using that bracket with the breather - manual diff tube here. Ended up having to get a hose on the breather barb and tightening it down with a worm clamp. PITA tight space to work.

 

I'm with @Bivouac though. No reason I can think of for the seal to just start leaking. I bet its coming from the top. Any chance it could be engine oil (if recently changed because that drip fluid looks clean and fresh)?

 

You really need to spend some time with degreaser and a pressure washer to be able to tell where the leak is originating from. The area where you're showing is the lowest point so of course you're going to see the drip there. I'm very familiar with how these 7.5" clamshell differentials go together and I'd be surprised if the leak is coming from the case at that spot.

I agree with the others that stated it very well could be coming from the breather hose. There's a short rubber section between the case nipple and metal hard line that maybe sprung a leak or somehow became dislodged from the nipple.

If you loosen the two front differential mounting bracket bolts, the differential will droop down giving you more access to see the top of the differential. You will get your best view from looking over the front cross member the steering rack bolts to.

If it does come to the point you want to pull the differential, I have two videos to help you out. In the first video, Part 1, we struggled with the removal and reinstallation of the differential. Since making that first video, I learned some tips and techniques that I feature in Part 2, so I highly recommend you watch Part 2 before pulling the diff.

The 3rd video posted shows how to rebuild the front diff so you can get an idea how it comes apart if you feel it's necessary to fix your leak. Good luck!

https://www.youtube.com/embed/w_gPiDvh9v4

https://www.youtube.com/embed/bOOxfDFUFsA

https://www.youtube.com/embed/sUzVndDO8To

 

Question - where would this part be located? It states it fits my truck, yet I don't see it. Nor do I see it in the diagram that seems to pertain to my truck.
https://parts.toyotaofsmithfield.co...um-Check-Valve-Front/62982476/9091710065.html

I changed that about a month ago.
The only active leak has been a small one from the right cv axle seal.

This one here is a new leak & not small. Like, I wouldn't want to drive it too far if at all size.

 

I think the part you linked is an inline check valve that attaches to vacuum lines near the engine oil filler cap and upper plenum.

@Area51Runner brought up a good point. Are you sure that is gear oil and not engine oil? Your new leak could be an engine leak and not a front differential leak. Have you checked the level in your front diff and have you checked your engine oil level? Maybe you've developed a leak at your crankshaft seal.

 

It definitely smells like gear oil. I suppose i is possible that I'm picking up the smell from the spray from the left cv axle seal when it was leaking. I thought I had cleaned that up though. I had to get a new drain plug for the front diff because the old one was leaking. Then I got some crappy washers, which still leaked. Now it's all good. Point is I was cleaning it up regularly to make sure it was no longer leaking.

I am going to check fluid levels. The leaky cv axle (right one) might cause a false reading though.