Front Differential Vent Hose Inspection/Replacement

While I'm unlikely to be going through any significant bodies of water with my Taco anytime soon, I'd still like to check all of the most problematic vent lines and replace where necessary (or just do it since they're all ten years old now). I fixed the split end on the transfer case actuator hose, but I'll be putting in a small extension using some 1/8 OD copper flex line to take all of the stress off the hose since it's kinda tight now. Front actuator hose looks good.

But that damned front diff vent hose... ZOMG, I can't even see the damned thing where it connects to the metal nipple. Can't get my hand properly up there, only able to get a finger to touch the edge of the hose. I think that I read that it has a lower section of hose, a metal intermediate line, then more hose. I'd really like to just replace it (the lower end anyway) and be done with it for peace of mind, but short of removing the rack and pinion (or worse) I don't know how anyone could do that.

I searched a lot for info on this but most posts are about the breather burping out some gear oil. Looking forward to the discussion, unless of course all ya'll got is bad news.

 

There are 2 of them. 1 for the ADD and one for the Diff itself. The one for the diff is a bear. It has 2 hoses and a metal tube. It’s the larger diameter hose.

See post #7 here for a better explain of where and how. - https://www.tacomaworld.com/threads/front-diff-water-intrusion.729841/#post-25994299

 

Thanks. That's one of the threads I had tracked down as well. Helped to see that the nipple on the differential is at a right angle.

I suppose an inspection camera would let me at least see if the lower hose section is in good shape. It probably is, but I don't want to assume it.

Would like to know how one would replace it if needed. I'm sure it's much more work than a short section of hose should require. From my vantage point it looked like with the rack and pinion removed I could get my hand in there.

 

Before I removed the rack and pinion. I’d see if there was any way I could loosen the diff and rotate it down some?

I don’t know if that is possible?
Or if it will help?

 

I do seem to recall a thread or two that discussed dropping the front diff, but that may have been in reference to actually lowering it when adding a lift. I'll do a little searching and see.

I may have spent a bit too much time reading TW after buying my Taco, there are a lot of "I kinda remember reading something about XXX" swimming around in my brain.

 

I’d worry more about the rear breather.
Mine got stuck closed and blew out my axle seal.
Or that’s my theory anyways.

You can do the rear breather relocation, replace the breather regularly, or jiggle the breather on the Diff.
I usually flick it with my finger a few times a year. I don’t know if it will help keep it free.
But doing the rear seal isn’t something I ever want to do again.

I plan to let a shop do it when I need rear bearings. (If I’m lucky)

 

When I swapped my front diff it was a bitch to get my hand up there and slip it onto to the union. Bolted in place, you won't get your hand up there unless you have hands the size of Barbie, and barely at that.
The hose length is also barely long enough, and thats with it stretched. The diff will need to be dropped at least a little to have room to work and I recommend buying two hoses to splice an additional couple inches of length. I normally find vacuum or air hoses that fail are usually stressed.

 

The front is a bitch to get to, it's held on with a bracket that's bolted to the diff. You need to contort the hell out of yourself to check and reinstall it. If you've never dropped the diff there's likely no reason to mess with it, at least I wouldn't

 

So.. I forgot to plug in my breathers for the front diff when I did my gears. Fast forward a few months and my truck got stuck in gear and I had to pull my transmission. Silver lining was with the trans dropped the engine picked up enough I could fit my big ol mit in there and get the hoses plugged in and even with some finagling able to get the little bolt in. Long hog nose pliers and a gear wrench are your friends. I think if you undid the trans crossmember and lowered the trans down you could get at it the same as I did. Wasn’t a walk in the park but 100% doable.

 

I tried this method and it was a no go. I left the CVs in and let it drop but it doesn’t get you anywhere.

 

it won't help much because even if the diff rotates that bolt keeps the vent at the top of the diff and still very little room to work in there

Crappy picture sorry but you can see this little rubber coupling that connects between the diff and the hard mounted tube.

 

Noticed the link that @TnShooter provided has a much better pic of that little rubber coupling.

 

I concur. I got it without pulling the rack or diff When the weight of the trans rotates the engine up on the mounts it opened it up enough to get at it.

 

The vent valves clog. They can be bought separately. The last one I replaced was a silver one I put on the rear diff along with a relocate.
When they clog, it may not allow release and/or vacuum at all.
They are cheap. At that point replacing the valve would be recommended.
I need to find time to get to the fronts. To check their function, possibly replace valves, and relocate higher if needed. The fronts might already locate up high to the engine bay. As opposed to rear diff which in stock config did not.

Or you can be one of the common peasants, known by their call "MUH TACOMA RELIABLE" and neglect it
then post how you destroyed it going through some water because the vent valves didn't function
so that we can all laugh

 

The front does not have a vent, it's just a straight tube to one of those two way "breathers" up in the engine bay. Maybe that's considered the "vent"? It seems more like a cap so foreign material doesn't makes its way into the vent but I've not checked much into it.

 

breather, vent, same thing
they have many different part numbers and versions

one way to test is with a vacuum pump that can also create pressure
or blowing and sucking on it with your mouth

transmissions and diffs usually have them. To keep pressure at a normal level.
Heat, moving parts inside? Pressure increase. Has to vent out.
Hit cold water, shrinking things? Pressure decrease. Can suck water through the seals because of that vacuum. Hopefully prevented by a working breather to let it suck air out the top breather and not a shaft seal.

same thing happens if you pump too much fluid into one of those units. It sprays out the breather.
Car breathers are usually right on the unit (trans, diff) without any hoses, because the mfg never intends their street car to do a water crossing

or even if it's just a flood, heavy downpour.
If you've ever been caught in one, I'm sure you enjoyed driving past all the people in their sedans struggling and shitting their pants, while the Tacoma felt like it was doing fine, whether it had a lift big tires and deep tread or not
and those conditions can also get water splashing onto the drivetrain



if each unit is it's own thing with separately enclosed fluid, I am assuming each has it's own vent. I believe that is the group of them I saw under the hood connecting with hoses but I may be wrong.
(front diff, transfer case, manual trans)

if they don't have that setup stock, it's probably what I would want to retrofit.
(hoses up high, vent/breather at end)
I bet there's room
another benefit of trucks: roomy engine bays to put lots of useful and beneficial things. Unlike a Mini Cooper

yes, the breathers have an integrated cap
I believe they are supposed to allow in/out air flow through the hose

this is how most regular car breathers are. They are set up for the greatest adventure to be Wal-Mart Parking Lot



If you look up DIY's to try and figure out the valve part numbers, people list different ones. Some being screw in. Others a shaft to slide and clamp a hose on.
Some of them one-way vent, some of them two way.
I'm not sure why a one way even exists or why to get it. As opposed to a two-way that seems better.
In other words, don't accidentally buy a shiny new one from the dealer using some part number you found online, only to do the blow test on it before installing and find it doesn't allow vacuum, making you have to figure out what other part number to get

 

Thanks everyone for sharing your experiences. I think the above line covers it, tho. I'm thinking to buy a relatively inexpensive inspection camera (have some other places to make use of it as well) and make sure the hose is in okay shape. Like CadCamMan said, these sorts of hoses usually fail because they're stressed and this lower one is short and straight.

I'll do my best to remember to have it changed if something gets worked on that might provide access.

 

Did you do this specifically to get at the hose, or were you tackling another repair at the time so that you could access the hose?

Also, might this rotation put any undue stress on the motor mounts?

 

I did it pull my transmission. If it didn’t rotate on the motor mounts you would be pretty screwed getting the top couple bolts out of the bell housing or be able to get the wiring harness off.

 

the feelings of the stock motor mounts do not matter
they are garbage and should be upgraded
on a good day, they can fuck up your frame
don't believe me. Just wait.

removing front diff is probably not that hard

Amazon has inspection cameras that use mobile app and powerbank