I would either check it regularly or install the "Axle Vent Mod". If you search the forum, you will find it. It essentially extends the vent to behind the passenger side tail light. It also adds an air filter and eliminates the one-way valve allowing the axle to breathe.

After the mod, I would still check the filter occasionally. Doubt you will need to change it very often. Cost me about $25 in parts (including the filter)...

 

What size is the threads on this fitting and why are there so many opinions on what the threads really are ??

 

The vent is not supposed to be a regular maintenance item, but Nissan knows they have a problem with them so some dealers will make it practice to check them. My driver side seals blew and started leaking in the first 10,000 miles. I had it fixed under warranty, installed the vent mod with a hose and filter, and so far haven't had an issue in the last 9,000 miles.

 

Can you, or someone, tell me what 'checking' it involves? I don't off-road so am not inclined to do the mod. However, if this checking, and perhaps keeping clear, is something I can do with very minimal tools I'd like to know how. I have found where it is and the area is relatively clean.

 

Had my buddy change the diff fluid in my '00 right before I sold it...he also checked the (original) axle vent. It was clear and had nearly 185k miles at that point...though all on the street = no off-roading.
YMMV (lol)

 

Had my buddy change the diff fluid in my '00 right before I sold it...he also checked the (original) axle vent. It was clear and had nearly 185k miles at that point...though all on the street = no off-roading.
YMMV (lol)

YMMV is 100% correct. A dry climate may be one thing, but in areas like here in MN, you can end up driving in a salty, sandy, wet, sloppy mess from November to April.

 

The existing piece is spring loaded. You should be able to freely push down on it and have it move about 1/8 of an inch. My understanding is the piece is a one-way valve and if pressure build up, there is no release, and that is what does the seals in.

Given how easy and inexpensive the mod is, I went ahead and did it anyway. I don't do much off-road, but figure the mod will reduce the chances of trouble later.

Without the mod, I would think if it becomes covered in dirt/mud/whatever, and no longer freely moves, I would pull it and clean (or replace) it. Can't imagine it is very expensive.

 

Right, the valve is spring loaded and the idea is to keep stuff from getting in but let air breathe out. Since it's mounted so low, it accumulates grime, road salt, water, mud, etc. over time and stops working properly. In my opinion it's a crappy design. American brand 4x4s have had vent lines running up to higher and protected locations on the vehicle body for as long as I can remember.

 

When a friend of mine (hes a mechanic and gets a discount on parts at Nissan) purchased my rear brakes for me, the parts guys told him that they change out the diff vent when they do the rear brakes, so I changed mine then. Not sure how official that policy is or if its in the service manual. That said my rear diff had water in with the fluid and all the bearings were shot, so I will be doing the relocation mod like mentioned above once the parts finally come in, not sure if the vent is what leaked though or it could have been the old one that leaked I guess.

 

I figure for the $25 in parts and hour of labor, it was worth the effort. It would seem that the construction of the valve would only let air flow in one direction when working and not at all when plugged. Without the free flow of air in both directions, there would be some pressure exerted on the seals. Also the fact that it lets water in, was enough to convince me it was worth the effort to do.

It may not make a difference, but it certainly doesn't hurt anything either...

 

The 2011 KC SV I just purchased has 54k on it. Previously owned in Utah
and Oregon, the valve was clean and functioning properly upon inspection
last week. I decided to move forward with the cheap mod anyway.

Initially I contemplated stainless steel braided hose, then fuel line, before
settling for silicone tubing because of the purdy colors available.

 

... the valve was clean and functioning properly upon inspection last week. I decided to move forward with the cheap mod anyway. ...

So what is the inspection that allows you to determine it is functioning properly, short of seeing lube dripping from a blown seal as a sign it is not. Mine is clean that's as far as I know.

 

Why me?

Dang it my left rear axle seal has blown and when I took the fill plug out there was some pressure released

I think I caused it myself, when I put the PRG rear cover on I filled past the service plug thinking a bit more gear oil could only help with heat and wear. I had almost 3qts in there, my own stupid fault. Oh well you live and learn.

 

ohhhh, i thought you were hinting I missed a big step.
the vent/valve used on our trucks is similar to many others out
there on other vehicles. just YOUTUBE it and you'll see many
methods used to manipulate and checking the valve

 

Even better, I'll do just that. Thanks again.

 

Other things to consider with this repair

If your axle vent fails or your axle seal just decides it's time to retire. You'll be looking at new parking brake shoes and rear pads. If they get soaked with gear oil and you don't find/fix it quickly, no good you can't buy just one side. And I just replaced my pad's <1k.

I think I've caught it early enough I'm just cleaning the pads/shoes and rotor. Since lowering the gear oil level and relieving the pressure, I'm going to see if the seal stops leaking?

 

My right side just blew. 55k miles, so should be covered under the powertrain warranty.

 

For anyone here who is confused on HOW the stock axle vent 'breather' works. Its a 1-way valve. When the axle heats up as you go down the road, the valve releases the pressure.
The problem is when it all cools down (rests in a parking spot, hits water, whatever you come up with) it draws air in past the axle seals. If it cools because you're in water (or even raining), it will likely pull in water splashed up onto the axle seal faces or pinion face. This is bad. The relocation guarantees it will breathe freely from a safe location. Even if it never sees water/rain/snow and is always garaged, using your seals as a breather ingress is a bad idea.
You owe it to your truck to replace the stock 1-way with a remote breather.

 

This is good information presented clearly, thank you.

I was under the mis-impression the stock breather was actually 2-way and that water could enter here when it cooled. So, am I correct that with the remote breather mod it does become 2-way, and so the seals are not vulnerable, or less so?

 

by design, the valves are one way. see if this helps

yes, the mod may, in effect, render the system into a 2 way breather.
but by virtue of the vented location (up high) the likelihood of water
and dirt to enter is practically nil

 

All fixed. They replaced the following under warranty: both axle seals, bearings, parking brake shoes, rotors, and pads.

 

Good deal! I'd be interested to hear what they had to say about it too, if anything.

Isn't this an acknowledgement by Nissan that the system is flawed; and by that I mean a design where a one-way breather valve will relieve pressure brought on by heat, but leaves no where for the ensuing lower temperature/low pressure to be relieved other than the axle seals. Seems crazy, unless I am still missing something (always possible).

 

I used a garden tractor fuel filter on the end of my hose. It's got a wire mesh screen in the middle. This will last longer over time. I plan to crawl under the truck every oil change and clean it off then reinstall. Should have no water going in at all now, but it can easily breathe both directions with no moving parts to fail.

 

I just bought my truck in july, as soon as i drove it over 40mph i could tell something was up in the rear end. I took it to nissan on the dime of the lot i bought it off of, only to find out the breather was totally rusted shut and thus my rear end was trashed. It sprayed diff oil everywhere like it projectile vomited at 100psi when they went to drain it. $2100 later (which i refused to pay a dime of) i had a new rear end. I noticed they ran a hose off the breather up to the truck bed. Do you think i should do anything else to this set up to bullet proof it?

if you cant duct it, **** it...

 

I would follow the advice in the original mod write-up thread and extend the hose from the truck bed location up and into the taillight cavity and add the breather filter. That's the best option ... not an open piece of tube under the truck bed. Still a chance to get water ad dirt in the tube in that location IMHO

 

checking the breather vent on a regular occasion is an absolute must. Toyota's are notorious for this issue once they get a few miles on them. i have had customers who i recommended this to and said nahh. Well a few thousand miles later they are dumping about a thousand bucks into fixing the blown out axle seals, brakes and other parts that are in need of service. My truck only has about 600 miles on her right how, but i will be checking every oil change. Good information on this thread!!

 

That's the really confusing part. 11 years (if not longer) of the same problem from a crappy design on a $1.50 part and yet Nissan and Toyota both still use the same design. It's cost them a LOT of money doing axle seal/bearing/fluid repairs and even some entire axle assembly replacements...but they still use the same crap $1.50 part. I don't understand the madness. It's like how the Chicago Bears keep playing Jay Cutler even though he throws the ball into row D seat 12 on a regular basis.

 

Note that this vent design as well as the location is common for the vast
majority of trucks on the market. This isn't limited to Toyota and Nissan

 

You have a point. However, from a manufacturer stand point a redesign is not cost effective and also the parts selling aspect of the business is important and very lucrative. Servicing on a regular basis at a quality shop (nissan/Toyota/ford) is therefore more important and recommended to prevent this from becoming a problem. The cost under warranty is minor considering how many of these jobs are done customer pay. I am sure the number of repairs under warranty is substantially less than that of customer pay. Preventive maintenance in this case is crucial.

 

71K on my 11 frontier and my Pinion seal crapped out. Luckily the certified powertrain warranty covered the pinion seal. Also my service writer noticed the rear diff breather was clogged. They replaced the rear diff breather and he suggested to perform the axle vent mod. I was afraid at first of performing this mod because I was afraid of it voiding my warranty. But now I will perform the axle mod. I should have done this mod a long time ago.

Chris

 

Is this just a 4wd Problem.

 

No, this also pertains to the 2WD rear axle …..

 

I have been following this thread and finally got motivated to look at my vent, 112k miles stock, never been touched. OMG it was a rusted hunk, it looked like a big barnacle. I brushed it and cleaned around it real well, put a stubby crescent wrench on it, it came loose easy. I used my fingers to remove it, the vacuum in the rear diff. was incredible. It actually pulled it out of my fingers and back down to the whole ? The strength and volume of that vacuum was impressive. It didn't pull any air in through the seals for sure. I ordered a new one on Ebay $9 and put it in. I will check it when the ODO hits 224k.

I'm new to Nissan but I do like my Frontier. Cars have been a serious hobby for me about 50 years, mostly VW's, Audi and Jeep. On thing that I have noticed with my Frontier is Nissan uses a lot of unplated steel... clips, brackets, bolts and washers. In most cases really doesn't affect the function of the part, just doesn't look pretty. In automotive parts procurement if you can save a nickle on a part you look like a hero.

 

Damn, I've been negligent. I thought the thing was just a vent with a splash cap. I usually twist the cap around and wiggle it when I'm under there. I didn't know it was a one way valve.

Time to order a couple for my "spare parts" stash.

We blew out the seals on our 97 Pathfinder like, back in 03, you'd have thought I'd have remembered.

 

You may want to consider getting a kit from offroadgorilla or nissteclifts. They are about $30 and come with a new barb, fuel line, and a filter so you can elevate everything in case you ever drive through high water. It also gets you away from the valve design that has the risk of getting clogged.

I installed the offroadgorilla kit last weekend. It took me less than 30 minutes to install and run the hose behind my tail light, and I should never have to worry about replacing it again. At worst, I will swap the filter at some point, but I doubt that will be necessary. Even if that was the case, it should keep me from having to mess with anything at the axle. I am always concerned about shearing off something like a valve that has a hollow center.