Rear diff vent relocation

I understand that, I ask because I am not familiar with your warranty and its limitations. I personally have a basic ass warranty with my truck which doesn't give me much help either. Say if your truck stalled out in a flooded section of a residential street, would they fix your differential? If the answer is yes, then no need to risk it while under warranty.

Coot

 

If it was damaged in a flood, my guess is they would not fix it and would blame the flood. Insurance. Suppose it depends on the extent and location of the damage, though.

 

Well damn man, you got me on this one then. Too many "what ifs" to go either way haha.

Coot

 

My understanding is, it's not water entering the existing breather that's the problem. The existing breather is a one-way check valve - it allows excess pressure to vent out, but nothing to enter the diff. The problem folks are trying to avoid is - you're driving along, and come along a river crossing. Your rear diff is rather warm by this point. Once you enter the water, the diff cools down, causing the oil inside the rear diff to contract, creating a vacuum. The stock diff breather does its job, and doesn't allow anything to enter the diff. However, the seals on the diff, being aged and worn, allow the suction inside the diff to pull some water in, and thus contamination. The mod is to add a two-way breather somewhere up high where it can't (or at least really shouldn't) be submerged. Thus, when you enter the water and suction is created, air is sucked in through the breather, rather than water through the seals.

 

How come it looks like you didn't tighten your union all the way down flush with the rear axle in the photos

 

No need for it to be all the way flush, I put plumbers tape on it to seal the threads and just turned it down to it was pretty tight!

 

Hmmm, well hopefully I didn't screw mine up. I didn't use any plumbers tape and I tightened mine all the way down.

 

I'd pull it and put some on if it were me.

 

Water does NOT enter through the breather valve (vent)... Read my post above. It enters because there is NO breather at all on the rear diff, and a vacuum sucks water into the diff through the wheels/ axle.

 

If this is correct, what is the point of relocating it and using the original breather than? If people were putting a two way breather or a filter sure I can see the benefit but just relocating a one way valve higher up doesn't make much sense to me.

 

I'd still rather have the stock breather over a 2 way. I'd only trust a 2 way if it was located in the cab. I'd be much more worried of water seeping in from moisture in the air. Have you ever looked at the bed storage compartments after a storm? They're soaked.

 

To be even more clear, that THING that Toyota puts on the rear differential is NOT a breather, it is a VENT, with a one-way, spring loaded, check valve. It lets hot gasses out of the diff but does not allow air back in. This creates a vacuum condition inside the diff... and water, muddy water, air, etc. will get DRAWN into the diff via the axle seals.

With this mod, we recreate the SAME breather addition that TOYOTA puts on the FRONT (4WD)... up high. If the front needs it, why wouldn't the back???

 

OMG, NO! Read... above.

 

Appreciate this info David, I always thought the point of this was to keep water from getting in. Makes total sense that the diff cant breathe and so it vacuums in from the seals. I need to do this ASAP as I don't want to get screwed next time Im wheeling!

Coot

 

I wonder how much pressure is required for it to open? I took the stock breather off twice (wrong parts the first time). The first time I took it off the pressure inside almost blew the breather out of my hand. The second time there was another pressure release (much smaller though).

 

My comments about it not really being an issue still stand I have nothing beyond the sparse anecdotal evidence offered here. Also if truck driveline needs warranty service I would remove the mod before going to dealer.

 

I pulled it up just now put on a couple layers of plumbers tape but still almost has to go all the way down. I think I wrenched it on too hard the first time. Do you guys think I could of caused damage to the threads? As like as it is tight should I be ok? A rear diff replacement would be ugly and expensive if I screwed it up. Thanks

 

I NEED TO DO THIS MOD!!!

I have the parts sitting on my desk at home....

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I did it for peace of mind if nothing else. So cheap and so easy, why not?

 

So how does doing this mod prevent the vacuum from occurring if you reuse the stock check valve vent? By adding 4' of 3/8" tubing you are adding about 5 cubic inches extra of air to the diff, but the vacuum issue will still occur just with slightly less negative pressure due to the extra volume from the tubing.

Why the front is high up I don't know, maybe it's a different style of breather and not a check valve like the rear. I haven't looked.