Breathing a little easier: Extending Jeep JK axle breather lines

Let’s get one thing very clear: I hate mud. I mean, I hate it with a passion. And, I’m no submariner, either. That said, however, I don’t mind a decent water crossing every now and then, and the fact is, you never know what mishaps await you on the trail.

From the factory, the transmission breather hose terminates about 6 inches below and behind the white conduit label in this photo. (Good luck reaching that one!)

From the factory, the transmission breather hose terminates about 6 inches below and behind the white conduit label in this photo. (Good luck reaching that one!)

What am I getting to with all that? It’s time to extend my breather hoses. The Jeep JK has four breathers — the front and rear axles, the transfer case and the transmission. Jeeps with manual transmissions really only have to worry about three, as the transmission breather terminates just under the shift boot, and, if you’re planning to submerge your JK above that level, you’re probably not going to find much to hold your interest on this site!

Worth noting is that I’m classifying this as a modification still in progress. My transmission and transfer case breathers are in locations not meant for human hands, so I’m continuing to brainstorm a way to reach them. I’ll update this post when I finally extend those lines. Here, then, is a simple how-to for the Jeep’s most vulnerable breathers, the axles.

Also worth noting is how poor a job I did of washing the Jeep after our New Mexico trip. I think she’s still carrying around 10 pounds of dirt!

Materials needed

  • Approximately 10 feet of 5/16-inch fuel line
  • Two 5/16-inch hose clamps
  • Four 3/8-inch hose menders (You want a very tight fit here.)
  • One bag, 8-inch cable ties
  • Medium Phillips-head screwdriver
  • Small flashlight (optional)

Step one: Rear axle breather

We’ll start this project at the rear axle, which is the easiest breather to access. This hose terminates at the rearward end of the sheet metal inside the right rear fender well. Use a medium flat-head screwdriver to carefully remove the white breather cap from the factory 5/16 hose. Next, insert the 3/8-inch hose mender into the breather hose on one end and the new fuel line on the other. (A tiny drop of WD-40 on the mender will help if you can’t get the hose mender to fit.)

Run the hose clear of any moving parts and up to the empty space behind the right tail light. Easy access can be obtained by pushing up on the foam floor plate in the body panel. (I’d suggest filling the small gap you create with an expanding foam to prevent excess dirt and moisture buildup.) Remove the left upper and lower tail light screws and unclip the wiring harness to IMG_5440gain access (above, center) to the body cavity. Reinstall the white breather cap in the end of the extended hose, and affix to the body panel using cable ties, taking care to leave the cap in an upright position. NOTE: The placement in my photo above is temporary. I left myself enough extra hose to run the hose up to the highest point behind the tail light. Finally, remove the axle end of the breather hose and add a hose clamp. Return the hose to its fitting and tighten the clamp.

Step two: Front axle breather

The front axle breather is held to the left shock tower, and terminates just above the inner fender liner. To access the breather cap, turn the steering wheel all the way to the right and pull back on the fender liner. Remove the metal clip from the shock tower and pull down on the hose. As with the rear, use a screwdriver to pry off the cap and replace it with one end of the hose mender.

Carefully run the extended hose under the Jeep’s hard break lines and to the fire wall along the left inner quarter panel, loosely securing the hose with a zip tie where needed. (NOTE: Keep your zip ties loose to allow for axle flex on the trail.) Continue the hose along the firewall toward the center of the Jeep’s long axis, but terminate the line before it hangs over the headers or engine block to prevent a possible fire, should you ever overfill your differentials.

Total time to complete

About 20 minutes for just the axle breathers. (I spent another hour or so trying various ways to cleanly get at the transmission and transfer case breathers.)

Total project cost




    1. It’s extremely easy to do the axles. I see a lot of folks doing the others, but most just run new line and leave the old hose in place. I want to do mine a little cleaner than that.

      Liked by 1 person

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