Front Differential Leak

I have a 2005 2.7 4x4 that developed an oil pan leak due to rust. I have an indy shop that is local to me that has done decent and fairly priced work for me on the truck, but mostly just inspections, etc. because they are close.

I did a bit of research on the need to pull the front differential when replacing the lower oil pan, and talked to the shop and they agreed they'd need to pull the front diff. I know there are threads here that debate the need, but that's kind of beside the point for me because it was indeed pulled and replaced to fit the oil pan. The shop offered to let me get the pan because their cost for the part was about twice what I could get it at from Rock Auto.

Did the job in early October. I didn't drive it much until I had to make a 3 hour each way trip down to a big city airport for a trip. When I got back, the truck sat for a few days and I noticed a drip of gear oil -- actually by that time a spot about the size of an egg on the floor.

Inspected it best I could and it appeared to be coming from the top of the case on the passenger side, not from the seam, not from the fill or drain plug. Took it to the shop and they said it was from "rot," suggesting when the case got warm from my long trip it was simply weeping oil -- much like the oil pan I replaced that was doing just that. I asked if they may have failed to replace or broke the pressure relief/breather tube on that side of the case, and they looked at me like I was an idiot.

Now, every time I drive it an hour and let it sit it's really starting to drip, and with the cold and no lift or floor jack, best I can see is it may well be that tube that is rotten and the source.

Questions for the board are:

Is that tube fitting on the top of the front diff case replaceable? If so...without removing the front differential?

If the diff is not overfilled, would the oil be high enough while operating to come out of a break or crack in that breather tube?

Thanks for any thoughts. I really have learned a ton from you folks, and appreciate the time it takes to respond to questions and offer suggestions to everyone.

Jeff

 

Bump...mostly, but...

Figured out the nipple out of the housing for the breather tube is replaceable, but does anyone have thoughts on the other two questions in my post?

 

Last bump.

Any ideas on these two questions would be much appreciated.

 

Your diff isn’t going to leak by rusting through or rot, nor your oil pan, it’s most likely a seal and the shop replaced your pan and gasket when all you probably needed was an oil pan gasket. But, they had to pull the diff to do that anyway, I’m guessing. Most oils and fluids leak through a blown or bad seal or gasket.

It’s most likely after they reinstalled the diff it’s leaking through one of the axle seals that your cv axle go into. Can you take pictures from underneath at each side of the diff where your cv axles go in?


Here’s an example of a leak

 

Thank you! I caught the oil pan leak while changing the oil last April. First noticed a rusty spot bubbling on it it before it leaked a couple of years ago. I suspect a chip or chips in the paint on the pan ultimately bubbled from all of the salt we have up this way. A year after I caught it, there was a slight drip. I have no doubt it was rotted through. The seal was good. It was absolutely clear where the oil was coming from when I decided to have the pan replaced.

Can't get any pictures until it warms up considerably. It's not leaking at the points where the seals would be going into either cv/axle. I'm quite certain it is leaking at the breather tube outlet, and I'd imagine that nipple could well be rotted through or was close when they pulled and replaced it. I'm assuming they forgot that it had a breather tube attached at the top, and put some pressure on it causing the leak that is getting progressively worse.

So, assuming that's correct, do you or others have thoughts on whether: 1) the nipple/stem coming out of the case is replaceable without pulling the differential; and 2) whether a properly filled differential would generate enough pressure to push oil up into that nipple/stem to cause the kind of leaking I'm seeing?

 

Hadn't caught the photo you posted on the edit.

The leak is not on the side where the drain and fill plugs are located, and no oil is coming from the cv joint/axle seal off the differential. It's clear it is coming from the top of the case on the opposite side of what you show in this photo. And, I can barely see the tube/stem/nipple coming out of the top of the case that is where the rubber breather hose connects. It is wet, and that's why I've focused on the possibility that the tube was rotted from rust and is getting progressively worse. The question (and I assume it's obvious) is whether the case generates enough pressure to force oil up into that steel stem during normal operation.

Thanks for the photo. Wish I could snap a few but it's hostile out right now.

 

If you unbolt the front diff mounts from the frame you should be able to get to that nipple where the vent connects. And to answer your question, yes oil will come out of there if the differential is slightly over filled or you get foaming. When I did my front diff swap, I over filled it enough where it made it's way up the vent all the way to the engine bay . Once the extra leaked out it subsided, but it made a mess. Here you can see where the tube is connected to with it out of the truck

 

That's what I needed to know. Thanks! I had seen picks of salvaged front carriers that made it clear the tube came out of some sort of tube from that side of the case, but couldn't see one as clear as this.

I actually don't think this case is overfilled, and the tube base looks low enough that it comes close to the top of the oil as it sits when idle. If your differential is still out, do you think the fill plug is at approximately the same height as the base of that metal stem that the rubber breather connects to?

And, will the differential tip downward from the front when the two front mounting bolts are removed? Seems like if you can get an actuator off while in place, there should be access to the base of that stem without touching anything else, including the front mounting bolts.

Thanks, again! Appreciate it.

 

Just replaced my front CV axle on the passenger side and the fluid is leaking.
Not sure if I didn’t pound the seal in hard enough.
It was leaking a little before I replaced it. so I replaced the seal.
I’m gonna have to take the whole back apart to try again...

 

An oil pan certainly can rust through from the outside. And while I haven't seen it happen to an engine oil pan, I have seen it happen on a transmission oil pan.

 

Sorry for the late response, yes remove the two front bolts and it will tip far enough down to check. We actually just did this this past weekend swapping a friend's gears in his truck. The vent tube is a pain but make sure you know it's connected otherwise your differential and/or actuator can fill up with water.

My rule of thumb on those is, buy two cuz your probably gonna have to do it again. What depth did you set the seal? FSM specifies a depth of 0.189 to 0.229 in. from the lip of the differential tube

Not common on tacomas but it does happen on other vehicles. My oil pan on my 7.3 before I changed it out with a new one.

 

I banged it in all the way the first time! Lol
This time I went 4mm all the way around. May actually be a hair shy according to the dimensions you just stated. I read elsewhere it was 3-4mm.
But put some RTV sealant on it this time so I should be good!?
Cheers.

 

It's always a guess when it comes to it I've found, and somewhat luck of the draw. Hopefully for your sake you should be good. If not, take out the old seal and repeat lol. I'm not sure but the RTV probably can't hurt. I've never been able to tell if it leaks from the outer lip where the seal mates with the housing or the inner lip where the CV rides, but I think it's the latter of the two.

I've also seen where it will start to seep a bit, then you drive around for a while and maybe a chunk of dirt or something gets in there and seals it up, good luck hopefully yours remains leak free, they can be a pain for sure.

 

Thanks, 6 gear. I'll get to this in the next month and try to take some photos. Pretty sure the stem is rotten, causing my leak.

 

Sorry for another question, but do I need to support the front differential when removing the two front mounting bolts to tip the thing down and get a better look? Got enough of a look the other day to see oil all over the stub that hooks into the top of the differential, and also pulled the fill plug and nothing seeped out so it's no overfilled. That's a $4 part from a dealer, by the way...friggin' always the way, eh?

Thank you.

 

No support required, there is a 3rd bolt in the back of the differential on a bushing that will hold it up. You can loosen that up as well to get it to tilt down even more, it's a large Allen key type fastener. It's always small shit that ends up being a pain in the butt, I know that feeling lol

 

Thanks. I really appreciate it. I figured the third bolt would hold it, but don't need the $4 part to be my downfall.

 

Still have not tackled this, but had it on a lift yesterday for a state inspection and got a little more of a look. I'm thinking the best approach is probably to drop the front differential again and replace all metal parts of both the diff breather and the breather for the actuator up to the rubber hoses that move to the engine compartment. The actuator line looks rotten, and as I've mentioned I think the differential breather stub coming out of the case is rotten, as well.

Hate to keep popping up with questions short of pictures showing the mess and the ultimate solution, but I'm assuming the diff comes out again to tackle a wholesale replacement of the breather assemblies up to the rubber hoses, right?