How to: Extend your rear diff breather

Silver dude Dec 14, 2012

  1. Silver dude

    Silver dude Sliders Founding Member

    Messages:
    929
    Location:
    machesney park IL
    First some basics on the the breather. The breather is nothing more then a air vent for the rear axle. The breather equalizes the air inside of the diff case to the air outside as so its not under pressure. The axle heats up, hot air expands this pressure has to go somewhere. If it wasn't for the breather hot air would have to force it's way past the axle seals which would cause them to leak. So the breather vents this pressure.

    Whats wrong with the stock breather? The stock breather comes in two different designs according to model years the gen 1.0 version and the gen 1.5 version. The gen 1.0 is what I am documenting in these photos. The gen 1.0 allows the axle a fording depth of 30 inches (on my 3" lifted xterra) before water rushes in. You might say ahh I never ford water over 30 inches. But, face it crap happens. Say you get stuck in a mud pit and this water slowly seeps down the breather hose to the diff. You'll probably never know about it until it's to late. Meanwhile you'll be driving back and forth to work everyday with water in your gear oil until the gears or bearings fail. This exact situation happened to a fellow wheelin buddy in this mud pit. The bank was so steep on the way out it pushed the rear bumper under water on the exit. Two weeks later he had failure.
    [​IMG]

    The Gen 1.5 uses a cap with no hose which puts the vent dangerously low.
    [​IMG]


    So how might one prevent this issue from happening? By extending the breather hose to higher location of course.


    So start by climbing under your rig and locating the stock breather assembly.
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    Remove the hose from the nipple. Its best to slit the hose with a razor as to not over stress the thin walls of the nipple.
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    Or in my case bust the nipple off. Mine was a little rusted and as a result of trying to remove the hose it broke. If yours breaks remove it with a 13mm or 1/2" wrench.
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    Reach over the frames cross member with a 10mm wrench to locate the screw to remove the breather assembly.
    [​IMG]

    [​IMG]

    The design of the stock breather assembly is actually pretty ingenious. The bit of metal nipple extends to about the middle on that box. The box prevents water coming in. Much like putting a drinking glasses rim down in a bath of water, air gets trapped in the box and stops water from coming in. But, of course if its just little sideways water pours into the box. I debated to reuse this device but found it unnecessary.
    [​IMG]

    When shopping for new nipples you have a few options. I found the brass one at a local hardware store. I was just uncertain say worst case scenario a branch grabs a hold of the line, if it would survive as well as steel. The nipples were each under $2. I special ordered the steel nipple from Mcmaster.com
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    I couldn't completely find a exact match. 1/8 NPT was as close as I could find to stock nipple. The thread pitch is the same the taper of the threads is a little different.
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    As a result the new nipples will only thread in about 1/4 of a inch. Which is plenty as that is close to the thickness of the axle tube. If it really bothers you, you could run a 1/8 NPT tap down the hole to adjust the taper. Or you could locate the correct fitting though probably more expensive. Or reuse the stock one. Or order a new stock one part number 38323-C601A , its around $3, threads in with no problems at all. Pipe dope or Teflon tape is recommended for the threads.
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    Buy 8 feet of rubber hose. I used 1/4 rubber hose.
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    Wall thickness is your choice, I chose 3/8 OD as its closest to stock and remains very flexible which might make it have less of a chance of cracking or over stressing the nipple. Most hardware stores will sell you 1/2 OD as it more common. Stay with a hose deigned for petroleum, like fuel line hose, the hose has to be able to take the fumes of gear oil and withstand a aggressive weathering environment.
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    Start by removing the tail light. Remove the two Phillips head screws visible in the pic. After removing the screws pull directly straight back to release the tail light. You can either remove the tail light or just leave it there to hang out as I did.
    [​IMG]

    Tape off the end of the hose you plan to use. I did this so that the dirt in the frame won't find it's way into the tube.
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    Insert the tube into the frame hole just behind the cross member.
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    Push hose in until you see a pretty large section coming out the back of the rail near the rear shackle.
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    At the end of the rail there is hole facing straight up. Insert the tube into the hole and thread it over the frame towards the bumperette.
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    [​IMG]

    Thread it between the bumperette and the tail lamp assembly.
    [​IMG]

    [​IMG]
     
    J Everett likes this.
  2. Silver dude

    Silver dude Sliders Founding Member

    Messages:
    929
    Location:
    machesney park IL
    At this point you could remove the tape and leave it be or you could take it one step further as I did.




    Here you see a little plastic nub.
    [​IMG]

    Cut it off, a rotary tools would work the best through I used a saw blade by hand.
    [​IMG]

    Use a drill to drill a 3/8 hole in the flange that sticks out.
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    Thread hose through hole and point it towards the shelf. The shelf should stop any rain water that may trickle down.
    [​IMG]


    Now if you want to take it one step even further.


    Buy a 1/8 NPT thread air filter and fitting from Mcmaster.com or a local pneumatics place.
    [​IMG]

    This will prevent any bugs, spyders, or dirt from crawling down the line and clogging it.
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    Make sure the end of the line is within air flow not pushed flush against the end of the tail light.
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    Finished install.
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    After tinkering with the hose setup the best way I found to secure the hose above the axle was with zipties. This was was because the hose had to rest a certain way to be away from the hot exhaust. Make it as long as necessary at full droop. I made mine a little long as I figure I'll cut to to length next time I get the rear drooped out.
    [​IMG]


    Enjoy your new 47" inch rear fording depth 17" over stock. Face it if it gets this high you'll have other problems.
    [​IMG]


    Mcmaster part numbers:

    Breather vent
    9833K21

    5645K224
    Medium Pressure Fuel and Oil Transfer Hose

    5350K31
    Zinc-Plated Steel Barbed Hose Fitting

    Hardware store parts:

    Small hose clamp

    1/4 nipple female 1/8NPT

    Less then $20 in parts.
     
    NMTerras and Roadwarrior like this.
  3. drbandkgb

    drbandkgb Titan Swapped / SAS'd Founding Member

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    11,187
    Great write up sir..
     
  4. Timrich

    Timrich Super Duper Moderator Founding Member

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    Still need to do this. Nice write up!

    Sent from my Galaxy S III
     
  5. Roadwarrior

    Roadwarrior Titan Swapped / SAS'd Founding Member

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    Looks great, will look into doing this over break.
     
  6. Mirage

    Mirage <img src="http://i164.photobucket.com/albums/u7/ra Founding Member

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    FYI, the OEM Nissan part number is 38323-C601A for a barbed nipple that threads right into the axle housing, should be around $3. This is a great easy/cheap mod for piece of mind for those that get into a lot of water/mud.
     
    J Everett likes this.
  7. NMTerras

    NMTerras Suspension Lift

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  8. J Everett

    J Everett Suspension Lift Founding Member

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    Mirage beat me to it. This part and mod also works for the 2nd gen; both the C200 and M226 axles use the same nipple as the H233B in the first gen.

    I really need to get around to doing this mod. I've had the parts for it since last year when I had the '08. Just lazy. Maybe next week I'll finally get around to it.
     
  9. TKDx00

    TKDx00 Lockers Installed Founding Member

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    I've been waiting for you to do this on XN. I don't go to the other site it's on. THANKS!!!
     
  10. Roadwarrior

    Roadwarrior Titan Swapped / SAS'd Founding Member

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    Just finished this mod.. Heck, with this write up the hardest part about this was driving to the store to get the parts..

    Awesome write up as always Ben.
     
  11. Prime

    Prime Some Kind of In Charge? Admin

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    This is still on my list of things to do. Maybe when I do the lift....
     
  12. Roadwarrior

    Roadwarrior Titan Swapped / SAS'd Founding Member

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    It takes all of 5 minutes to do post buying the parts..
     
  13. Xterraforce

    Xterraforce <img src="http://i164.photobucket.com/albums/u7/ra Founding Member

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    That's what I forgot to do. :zomg: I've done this on every 4x4 I've owned but totally forgot to do it on the X. Thanks for the write up. I'll do this ASAP and change the fluid since the bumpers have been under water a few times.
     
  14. Roadwarrior

    Roadwarrior Titan Swapped / SAS'd Founding Member

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    I need to replace my rear fluid.
     
  15. Pro-2X

    Pro-2X Suspension Lift

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    Waiting on my BTF cover to do mine.
     
  16. Xterraforce

    Xterraforce <img src="http://i164.photobucket.com/albums/u7/ra Founding Member

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    Done.


    [​IMG]


    One thing I've always done is to turn the vent hose back down and add a filter. It just makes me feel better. The final installed located is at the very top of the tail light opening.


    [​IMG]
     
  17. Silver dude

    Silver dude Sliders Founding Member

    Messages:
    929
    Location:
    machesney park IL
    Nicely done! love the curve.
     
  18. XterraKevin

    XterraKevin Bought an X

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    Dang! That is awesome! I need to do this still
     
  19. xterra terrestrial

    xterra terrestrial Test Drive

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    Last edited: Sep 23, 2014
  20. J Everett

    J Everett Suspension Lift Founding Member

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    I like that. Just gives room for expansion/contraction of gasses. I think I'd do that if I had not already extended the breather line.
     
  21. Tay-Lo

    Tay-Lo I'm the king of junk food! Supporting Member

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    Wow thats awesome. I guess it's a good thing I forgot to do this mod last week

    Sent from my pocket computer
     
  22. xterra terrestrial

    xterra terrestrial Test Drive

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    Location:
    canada
    might just order me another one.
     
  23. geekyrocketguy

    geekyrocketguy Test Drive

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    Location:
    Hilo, HI
    I bought these parts from McMaster-Carr, but the recommended nipple fitting didn't fit into the axle of my 2006 Xterra, which supposedly has the same size as the 1st-gen one. It just barely didn't fit, so the failure may have just come down to the relative tolerances of the axle and the nipple fitting.

    THE PROPER PART TO BUY is Nissan 38323-C6010. It can be found online, or my local Nissan dealer sold it to me for $4.50. This fit into my axle just fine. The stem of it is 3/16" (or whatever the metric equivalent is), so the 1/4" fuel line that this thread told me to buy didn't really fit. I ended up slathering the nipple fitting with epoxy and then hose-clamping it tightly, but it was sub-optimal. So, readers of the future, buy the following:

    - Nissan part number 38323-C6010
    - 3/16" inner diameter fuel line x 8 ft long
    - small hose clamp
    - Whatever filter thing you want to put on the top end.
     
  24. J Everett

    J Everett Suspension Lift Founding Member

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    Location:
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    While this thread is active again, does anyone know if the transmission, transfer case, and front diff need breather extensions as well? Let's get that info in this thread, for all generations/variations of the Xterra.
     
  25. TJTJ

    TJTJ Skid Plates Founding Member

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    Excellent idea!

    I have noticed though, over the years, that Nissan seems to have varied what they used even w/in the same model year for some of these. The rear diffs with mushroom valves vs tubes to the frame for example, are quite varied.

    So far, tygon and worm clamps seem to work.

    :D
     
  26. Fromfrontier2Xterra

    Fromfrontier2Xterra I spend more money on comic books than my X Super Moderator Supporting Member

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    Front diff already has a breather that goes to stock air box. If you have a Volant like I do, I recommend getting a filter.

    Sent via my walkie talkie
     
  27. TJTJ

    TJTJ Skid Plates Founding Member

    Messages:
    1,492
    Location:
    NJ
    The OEM set-up was the front diff breather tube went to a metal tube up on the engine, between the block and firewall....not the air box, did you mod that?

    The air box is always under negative pressure when the engine is running. The breather tube needs to allow the air to expand out of the diff when its hot, and to be sucked back in (With no water preferably...) when its cooling...

    ...SO if the breather is always under suction, you can put the diff under lower pressure than outside it, and suck water in if your ends/seals, etc, leak for example, etc. If its at a neutral pressure (The PURPOSE of the breather), its less likely to be stressing those seals. If positive, it is less likely to leak in, but, a seal can be blown out, etc.

    SO, while not exactly a giant problem, its not a good idea to essentially use the air box as your breather. Simply extending the engine mounted tube up higher would be better.

    :D
     
  28. Silver dude

    Silver dude Sliders Founding Member

    Messages:
    929
    Location:
    machesney park IL
    The trans and transfer case vent to curls of pipe at the top of the bellhousing.
    [​IMG]

    I didn't find extension necessary as its pretty high up in the middle of the vehicle. I'd say up to the black molding pieces on the doors at least at that depth I'd be worried about other things like the ECU, intake or maybe floating down stream. Remember its the middle of the truck so either end could dunk way in on approach without issue. I guess it couldn't hurt though. Would be pretty easy to extend them.

    [​IMG]

    I'll have to get back to you on the front diff I'm actually not entirely sure where it ends at.
     
    Last edited: Mar 2, 2015
  29. Fromfrontier2Xterra

    Fromfrontier2Xterra I spend more money on comic books than my X Super Moderator Supporting Member

    Messages:
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    No. 2g OEM set up for front diff is to the airbox.

    http://www.clubxterra.org/forums/showthread.php?t=19698

    Thread and pictures on it there for reference.
     
  30. J Everett

    J Everett Suspension Lift Founding Member

    Messages:
    2,660
    Location:
    Houma, LA
    Yeah, I remember both that thread and disconnecting it from my airbox when I installed the Volant. I think I will find a filter for it.
     
  31. Oldfart

    Oldfart Test Drive

    Messages:
    10
    Let me add this, and only from my experience. Your diffs, t-case, and trans are all hot when wheeling. Bearing that in mind when you enter a mud hole, water crossing your compartments will be suddenly cooled by waters temp. It will immediately turn your vents into vacume tubes that actually siphon water in. If your wheeling, and it involves water this thread is awesome!
     

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