While performing a reconnaissance mission for the installation of my PMLI extra capacity differential cover I made a disturbing discovery. The design of the rear axle vent was unacceptable (to me) due to the possibility of water intrusion while 4 wheeling or at a boat ramp. The factory vent is basically a check valve that vents pressure to atmosphere (See Fig. 1). This type of vent invariably fails at some point in time and could allow the rear axle to become contaminated. A second problem, IMHO, is that when the axle cools with this type of vent it holds a vacuum inside the axle. This vacuum pulls in on the seals and when you resume driving the seals are being pulled extra hard into the shafts possibly causing extra seal wear. Now there are some types of seals that require pressure or vacuum to work, these are not they.
I consulted the Mickey Mouse engineering handbook and combined it with the “I slept in a Holiday Inn Express” attitude and came up with the following: First was a trip to Ace Hardware and the AutoZone. I purchased a 1/8MPT thread to hose adapter from the ACE. Much to my surprise that is the correct size. Next it was off to the AutoZone for six feet of 5/16 fuel line and a cheap fuel filter (no check valve style). See fig2. I chose to put a filter on there as a deterrent for dirt, dust and debris from getting into the vent tube and it was cheap so what the heck.
I then removed the stock breather and installed the adapter to the axle with a dab of sealant on the threads. I then clamped and routed the hose up into the right, rear taillight area and used some wire ties to keep it in place. Note; be sure to leave plenty of extra line between the axle and your first tie. There needs to be enough to allow for axle movement, especially extension. Fig 6 shows a good place run a tie in the taillight area.
The whole job was relatively quick, easy and well worth it for my needs. I did have a quick look at the front axle vent and it appears to be good. I’m pretty sure it’s the long tube that dumps right below the engine air filter box. I still need to figure out the transmission vent and transfer case vent…
Hope this was of interest and to the moderators, if this should have been put in the how to please move it as you see fit.