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How to: extending the rear diff vent

Old Dec 6, 2010 | 12:39 PM
  #1  
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Engine: 4.0L HO I-6, 703 Injectors, Brown Dog Super Engine Mounts
Default How to: extending the rear diff vent

This is my version of extending the vent tube for the rear axle.

There are a few guides around that say they put the end/filter inside the gas tank filler area - this a very "ghetto" IMO, and i didn't want to stare at it every time i opened the cap to fill my gas tank, and thought it might cause issues when it came time for the emissions gas cap pressure test...so i came up with a different solution.

I'm a big fan of hidden/reversible modifications (see my cowl snorkel mod for example https://www.cherokeeforum.com/f2/my-...snorkle-67919/), and i wanted this to be completely hidden, but very functional. I couldn't vent the axle inside the vehicle to keep from having to smell heavy gear oil every time i jumped in the jeep.

So this is what i ended up doing:

Parts list:
10 feet of 5/16" clear pvc tube ($5.60 for 10 feet at Home Depot)
1 hose clamp ($0.56)
1 F20011 Fuel filter ($4.11 at AA)

I would have preferred going for fuel line, but at $1.39/foot, i couldn't justify the cost over the HD tubing. I have about 6ft left over if it ever breaks/cracks.

In searching for a suitable place to mount the filter/tube outlet, i happened to consider the area around the taillights. When i took one off i gasped at the amount of space in the body behind the light, as well as in the light housing itself. Perfect! It's out of the way and hidden, and it's plenty high to avoid ever being dunked underwater.

Drilled a hole:



Attached the new tube to the axle with the hose clamp, ran it over some tubes and behind the gas tank support rod, and up over the tank to the filler area, and drilled a hole through the frame rail to pass the tube through. Secured with a wire clip.



Ran the tube though a rubber drain plug and up behind the light. Attached the filter and an extension tube to the top to run through the hole. I later trimmed the extension tube to about 3" past the hole, and bent the end down to fit in the void in the taillight housing.



So there it is - keeps water out, vents the axle, and is completely hidden from view. Hope this helps others considering this mod.
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Old Dec 6, 2010 | 12:43 PM
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Really?

Overkill

Never had a problem with my stock location.
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Old Dec 6, 2010 | 12:51 PM
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my stock location is at the side of the frame rail, about 6" above the top of the axle...

i suppose it is far more important on a stock ride height, especially if your wheeling spot has lots of mud pools where the depth sometimes comes over the rear bumper

Last edited by dukie564; Dec 6, 2010 at 01:13 PM.
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Old Jan 11, 2011 | 11:18 AM
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Originally Posted by XJ Stryker
Really?

Overkill

Never had a problem with my stock location.
you are a moderator and yet you badmouth someone trying to share info? I appreciate people sharing their ideas; if you don't like the mod, why dont you just not say anything? Good grief
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Old Jan 11, 2011 | 07:01 PM
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Originally Posted by chattacuda
you are a moderator and yet you badmouth someone trying to share info? I appreciate people sharing their ideas; if you don't like the mod, why dont you just not say anything? Good grief
I agree for someone who represents the site & community. It could have been worded better.
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Old Jan 11, 2011 | 09:52 PM
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Originally Posted by chattacuda
you are a moderator and yet you badmouth someone trying to share info? I appreciate people sharing their ideas; if you don't like the mod, why dont you just not say anything? Good grief
X2!!!!!
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Old Jan 11, 2011 | 10:17 PM
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sweet and i like the filter in there looks well done! and over kill not so much i have had water over my brake lights a couple times.
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Old Jan 11, 2011 | 10:32 PM
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Would that BMW check valve, thats used for the fuel line work as well?
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Old Jan 12, 2011 | 08:25 AM
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probably would, although i bet it's a ton more expensive than the filter i listed (that fuel filter was used specifically because it's anti-drainback)
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Old Jan 12, 2011 | 08:54 AM
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Originally Posted by chattacuda
you are a moderator and yet you badmouth someone trying to share info? I appreciate people sharing their ideas; if you don't like the mod, why dont you just not say anything? Good grief
Originally Posted by Jackup
I agree for someone who represents the site & community. It could have been worded better.
Originally Posted by bajaxj
X2!!!!!
Whoooooooooooooooooooooooooooa!!
Back up the Bash Bus folks.

Being a Mod does not mean that he's not entitled to an opinion.
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Old Jan 12, 2011 | 12:30 PM
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So the main purpose of the filter is to keep liquids from draining down the tube? I'll be doing this mod but I just want to understand it also....sorry I'm being slow on this.

Also, showing my newbness I'm sure, does the front diff have a vent? And if it does should this be extended as well?
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Old Jan 12, 2011 | 12:37 PM
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yes.

the front diff does have a vent - you'll have to look where yours goes to. Mine extended all the way up to the top near the brake booster from the factory, so i left it alone.

Also equally (if not more) important is to attach a breather to the top of the distributor cap. It'll kill your spark instantly if water gets in.
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Old Jan 12, 2011 | 01:03 PM
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Originally Posted by dukie564
yes.

the front diff does have a vent - you'll have to look where yours goes to. Mine extended all the way up to the top near the brake booster from the factory, so i left it alone.

Also equally (if not more) important is to attach a breather to the top of the distributor cap. It'll kill your spark instantly if water gets in.
Thanks a million for the ideas and the help.
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Old Jun 26, 2011 | 01:20 AM
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thank you very much i had no idea
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Old Jun 26, 2011 | 06:56 AM
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Originally Posted by dukie564
probably would, although i bet it's a ton more expensive than the filter i listed (that fuel filter was used specifically because it's anti-drainback)
I understand your thinking on using a filter with a check-valve, but I believe the "differential air" should be able to flow both ways. As the axle assembly gets hot, the air expands and needs a way out. When the axle gets sugmerged in water, it will rapidly cool and the air inside will contract and need a way in. If a check-valve (anti-drain back valve) prevents flow in one of these directions, the air will escape/enter from somewhere else (usually an axle seal). If that seal is currently underwater......
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