Diff Breathers

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Mar 27, 2003
Georgia Tech
Time for some diff breathers
Started pokin around the axle today, realized that those little caps pop right off using a screwdiver, and looks as though there is a little nipple that could be used as a fitting for some clear tubing. I don't see why you need to screw out whats there and then risk screwing up your axle threads screwing in a brass fitting that uses SAE threads. Why can't you just stick a tube right on there and tube clamp it on? If sealing is a problem I'll get some butyl rubber or silicon and seal it up with that as well. I think FJafrica did his breathers the way I am describing, is that true? If so how does it work?
That's how I did mine. I used 3/8" fuel line and a small hose clamp. I tied the 2 from the rear axle together then ran it up the frame and tied in the front axle . Then ran it up and tied it off at the top of the radiator holder.
I only have one from the rear as well. Popped the cap off as you described, clamped the pipe over it. Ran the pipe alongside the brakeline, into the frame, and out over the transfer case. There is another breather ontop of the transfer case, used a t-piece and tied into that one. From there it was led up behind the firewall and ends up just below the bonnet.
My 72 FJ40 has 2 breathers, one where the brake line connects and one on the left side of the diff. The front only has one.
Can all the breathers be T'd together, front, rear, and t-case and still breath properly? I was going to buy a kit, but it sounds like that may be unnessesary.. I'll just run them high into the engine compartment.
I just ran 5 (2-Diffs, 1-Trans, 2-Xfer) Festo quick connects.
Festo is a European pneumatics company so their threads are mainly ISO (metric). I have a goverment discount at work ;) so it's the obvious choice for me. They're cheap though. You can probably get them at Grainger or McMasterCarr.
I connected them all with 6mm ID tube and up top through the bib.

How'd you get to the ones above the tranny and transfer? I didn't even know there were any up there. I guess I could pop the tranny hump for a look-see? :dunno:
I just just put the rebuilt engine and tranny back on the frame so it's pretty easy for me to get to. If you pull the hump you'll be able to access the breathers for the tranny and transfer and also one on the 4wd vacuum engage if you have it.
Better to be safe than sorry since I was already there.
Good luck,
i'm simply curious why these components need to "breath"?
i'm simply curious why these components need to "breath"?

They need to breath because they have air and oil in them. The oil gets hot when you're driving, and the air gets hot and the pressure goes up. The breather lets some air out so you don't blow a seal and have all the oil leak out. The problem here is when you cross water - the hot diff hits the water, cools quickly, and the pressure goes down, so air (or water if it's under water) is sucked in through the breather. The stock breathers are not quite long enough for deep water crossings (some Cruiser models have hoses up to frame level, some just have little short things) and they have little valves on the ends that are supposed to let air out but not water in, but the valves tend to fail over the years. If you extend the breathers up high on your firewall you still allow to the components to breath but prevent getting water in your diffs. You don't want water in there - it's supposed to be oil only!

Some Cruisers have hose barbs sticking right out of the axles (like my FJ62), but some have other fittings that need to be replaced with hose barbs so you can extend them easily.

Hope this helps.
The transmission breather on my 3 speed is on the top of the shift plate. I'm sure it has to have one for the aformentioned reasons, although I guess the transmission could vent through the transfer case. Feel around on the tranny by the shifter, you might have to install a right angle fitting to allow for your hose.
Ed Long :)
I have a 4 speed mated to the F engine, I have checked that shifter plate before, but did not see anything. ??? I will definately relook at it again, is it possible that it breathes through the rubber boot around the shifter? The idea of it venting through the txf case also crossed my mind, yet they have seperate oil fillers, indicating totally seperate units.
Some Cruisers have hose barbs sticking right out of the axles (like my FJ62), but some have other fittings that need to be replaced with hose barbs so you can extend them easily.

That is a good point. My '87 FJ60 also has the extended breather lines. If you feel more secure with barbed type fittings, check your pick-a-part. I'm sure a hose clamp on the cap-less breather is fine.

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