Rear differential breather valve and pressure buildup

[NOT ME OR SOMEBODY]

I wanted to do the differential breather mod, but did not like the behind the gas fill lid placement.

I instead decided to run a 3/8' hose up into the engine compartment. ( this is where TOYOTA put the center and front diff. breathers at, so good enough for them good enough for the rear I say )

So after routing the hose the way I wanted it I put the OEM breather valve on the end in the engine compartment and went to the rear end to attach it to the fitting I had already screwed into the axle housing. But before attaching it I blew thru the new hose and found it had alot of resistance. Thought I may have kinked it but it was all ok. Thought it may have been the hose length causing this so I removed the OEM breather and then was able to blow very freely thru the hose. I blew thru the breather valve and it is the cause of most if not all of the resistance. The valve seems to function as it should and I don't think it was or is clogged. ( This runner has never been off the road much YET and never in serious mud...... IH8MUD too )

Unless somebody knows better I figure the less pressure in the Differential the better on the axle seals.

Am I right about this?

So now end of the hose is mounted up high in the engine compartment and is open with no breather, and the other end is attached to the rear axle.

I don't really care for this either but I'm thinking gee whiz by the time I ever get in water that deep ....:toilet3: well you know what I mean.

Is there alternative breather valves that may work better than the OEM?

Oh yeah the threads in the rear axle are just 1/8 pipe threads so if you want just go to a hardware store and get some 1/4 pipe thread barbed fittings and adapt them down to 1/8 pipe thread.

 

[Singtoe]

In my opinion, the factory breather on the end of your hose should work fine. The diff really doesn't breath but rather a vent to let the built up pressure escape. So if if you can blow through it, even though it is very restrictive, will still let the differential equalize to atmospheric pressure.

This is my opinion though.

 

[Nelsonmd]

In my opinion, the factory breather on the end of your hose should work fine. The diff really doesn't breath but rather a vent to let the built up pressure escape. So if if you can blow through it, even though it is very restrictive, will still let the differential equalize to atmospheric pressure.

This is my opinion though.

Yeah, very slow flow through it is ok as pressure isn't going to build up super quickly.

It is a pretty cheap part though. It is easy to get some contamination in there or corrosion that will freeze the internals. I'd just buy a new one.

 

[99runnerwa]

could you put a t union to join the rear diff and the transfer case breathers, then attach it to the silencer on the intake tube?

 

[Nelsonmd]

could you put a t union to join the rear diff and the transfer case breathers, then attach it to the silencer on the intake tube?

Sure, but I think that would be unnecessary. It is easier to just run from the rear axle to the gas tank spout, then do the TC to the engine bay. Remember that the front diff breather is up in the engine bay too.

If you are that concerned about water ingress to route it to your intake, then maybe you should just get a proper snorkel and route it there. Chances are you don't need that though.

 

[99runnerwa]

a snorkel is in the plans, but that is a while down the road. i just dont want to do things more than once.

 

[Drcoffee]

if your hose is in the engine compartment why not use a brass pneumatic breather like this? you just need to keep crud from getting in the hose end.

 

[CanukRunner]

ya my breather rusted out and blew my seals... I like that pneumatic thingy maybe put a foam filter material around it.. i could have sworn i saw some ford with aftermarket breathers that had foam at the top

On that note...could you imagine if someone actually piped a high pressure air line into the rear diff.. man that would be dumb...

That was sarcasm mr ARB,,, invent something better cause i really want one.

 

[Drcoffee]

So I did the breather mod this weekend and rather than cut a hole in the gas tank filler seal, I just looped the tubing all the way up to the top of the filler and back down about 12". Water won't climb an open tube so even if I go through water, I should be safe from water getting in the differential. Now I need to find a suitable breather to keep spiders out. Note the route is only 4' long and starts by heading back up to the center of the differential, up over the brake line bracket, over the frame cross member, back along the gas filler tube and up under the cover. Then route it back down within the plastic shield and zip tie it in place. The vent isn't moving much air, it just needs to relieve pressure. There is no outward evidence of the mod and because it routes back toward the center of the diff, the tube is always going upwards for drain back and enough length for full suspension travel. The open end of the hose is under the cover once you close it up.
*Note: NPT "pipe thread is not good at sealing so either use teflon tape or in my case I used red high temp silicone on the threads.

Here's a few pictures.

Here's what my breather looked like. Completely sealed.

(picture before hose clamp secured)

Push the hose up onto the top of the frame rail

 

[BearFromOBX]

Part of my checklist

A little help for a newbie please gang...
Over the next couple of weeks, I plan to complete checks on my 2000 4R (SE 3.4L with 4WD and nonlocking diff) reviewing it for reconditioning or replacement and inspections/fluid changes for the AT, and both differentials are on the list.

1. The photos in this post make the rear diff breather look like it is about 10 o'clock on the top of the main diff body; is that accurate?

2. Where does the breather attach to the front transfer case and is it factory piped up into the engine compartment? Pictures would be a great help if available.

3. Is there a breather for the AT or is it using the fill tube as it's breather?

Thanks in advance for your help!

 

[Bstrom]

Sure is a lot of discussion for such a simple subject. Just get that vent above any waterline you might cross and you're good.

Don't see why the filler neck location isn't good enough for some - that seal is there for vibration more than anything else. The shorter the better for this venting arrangement is a smart move.

Maybe someone will run one up their snorkel!