Differential and Transfer Case Vent/Breather Relocation

[Blackout]

Got pretty bored the past couple days so I decided to relocate my breathers into my engine compartment. Eventually, after a get a few other things sorted out first, I plan on putting together a snorkel as well. I sort of went overboard and decided I'd buy a couple of the specter breather filters. Probably unnecessary, but I had a discount at Advance Auto to make them pretty cheap and I like the look if nothing else.

Here's the parts I started with:



I ended up getting bigger zip ties, and replaced the red filter with two silver ones that you'll see later on, and purchased more hose clamps.
Here's a closeup on the hose I bought. 15 feet turned out to be more than enough. Purchased it at O'Reilly's for a little over a $1 a foot.



In case you haven't seen the post on the OS, here's the rear differential breather after I pulled it down. The breather itself pulled right out



Here's the transfer case breather line. It disappears up above the TC, but (at least mine) isn't connected to anything. I just pulled it down and let it hang until I ran the rest of the hose to it. As with the rear dif, the breather pulled right out.



I didn't get a picture of the front dif breather before I disconnected it from it's clamp, but this photo from the OS courtesy of JamesDowning shows it's location. The breather itself actually had to be cut from the line.



Now for the routing. The lower arrow show's the breather line coming from the rear dif. The upper arrow show's it's position running forward along the drivers side, then above the fuel tank.



The hose comes out above the fuel tank and runs above the TC, I zip tied it to one of the other hoses to keep it off the TC as much as possible.



The rear dif hose and TC hose meet up near the forward drive shaft then follow the frame via zip ties (lower arrow) into the engine bay, while being careful not to get them pinched against the UCA (upper arrow.) This is also where the front dif hose, (noticeably smaller then the rear) T's into the rear differential hose (middle arrow.)



The hoses both extend into the engine bay to the filters and their temporary positions near the fuse box until I can come up with a bracket to get them out of the way on the opposite side of the fuse box, attached to the fender.



Easy? Yes. Could I have done it cheaper? Yes. (filters at $8 each, extra hose at a little over $1 a foot, plenty of hose clamps and fittings all could have been avoided.) Fun little mod if you get bored and want to spend a little extra change. Didn't keep track exactly, but I'm sure someone can do this mod at around $20-$30 with the right amount of fittings, hose clamps, hose length, and minus the filters.

[bgwolfpack]

Nicely done!
Not an expensive mod either and well done!

The filters look cool too. Great conversation peace.

[Gordinho80]

Why not just use 1 filter for all vents? Route everything to 1 location? Don't you also have to relocate the trans vent?

[Blackout]

I was planning on doing it that way, but then I was worried about the possibility of fluids feeding into the lines and mixing in with each other. Not sure if that would even be possible. Thoughts? If this isn't an issue, then I can just get rid of the other line and use a T fitting to hook them both together and take the filter back to the store. I need to get back under the truck with a mirror and flashlight to check out the top of the transmission to see if there's a vent there too. I know in the thread on the OS, they were thinking it vented through the dip-stick. Anyone know the answer to that?

[bgwolfpack]

No need to vent the dip-stick tube. The vent, for the transmission, is located on the passenger side of the transmission case almost at the top. It just goes out to air but could cause a problem if tied in with the other breathers if it started to puke out fluid if having mechanical issues.

[irishboy02]

Let me start by saying that I cant see the pics from this computer. However i will proceed...

First, I would not recommend tieing these together with a T fitting. Each needs to be able to breathe independently.
Secondly, as per COMPNINE you can see that the front and rear vent pieces are actually very different.

http://www.compnine.com/index.php?u=1&year=2005&artnbr=TS05-028&artsfx=NULL&supplgroup=NULL&catcode=56S&modelcode=T&makecode=LC&modelseries=NULL&uid=1&modelid=7156&capuid=1&majorgroup=05&grouptype=B
Rear vent GM# 15771000

http://www.compnine.com/index.php?u=1&year=2005&artnbr=TT06-110&artsfx=NULL&supplgroup=NULL&catcode=56S&modelcode=T&makecode=LC&modelseries=NULL&uid=1&modelid=7156&capuid=1&majorgroup=06&grouptype=B
Front vent GM# 15743069

I actually just went through this because i somehow lost my front breather completely. I was speaking directly with GM techs and Parts guys and they said there is a difference in the vents. These 'caps' if you will, for lack of a better word, are designed to allow the fluid to expand and contract in a fluid (no pun intended) motion. The change happens rapidly, as the ambient temp changes, or the internal changes. For instance if your running in 4wd with it 90degF outside its going to be hot fluid. Then you splash through a cold river, that quick temp change will cause the fluid to change rapidly, needing this room for expansion - however the exchange works in both directions. This is the same for the rear diff and TC, but not necessarily only in 4wd. The gm parts are able to accommodate airflow both ways. These breathers do not allow that. There is the availability of suction, sucking in clean air, but at the time the fluid wants to expand, it will push the air up the tube and attempt to reverse the flow of the filter element. It will still get through but it will build pressure and not be able to change rapidly.

This is my understanding. I could very well be wrong but thats just my $.02

[Blackout]

With how tiny those little vent "caps" are, I can't imagine it'll have that much difficulty breathing out through these filters. I'm sure there will be a slight pressure build up, but I doubt enough to make that much of a difference over the stock breathers. That's a good thought, maybe I'll swap some fittings and run the front dif independently from the rear.

[chevycrew]

We have always just used cheapo plastic fuel filters.

I think its safe to tie in like fluids to each other, just in case it pushes some up. But realistically, you should be safe running them all to a single breather.


One that many people forget to seal and vent, is the power steering.

[Trail X]

First of all, thanks for posting this and trying it all out. Much props!!

I don't think there's any reason to split the vents and run dual filters. The only way they will ever really back feed any large amount of fluid is if you turn the truck upside down... and if you do that, you're not going to be concerned with mixing fluids. In reality you probably don't need a separate vent for the breather tubes, just T the whole system into the intake (just do it ahead of the throttle).

My early notion of the trans breathing through it's dip stick was wrong, I think that hypothesis was before we had wonderful compnine as a resource.

Randy is also probably right, the only one that could conceivably burp any real amount of fluid is the transmission because it probably has the largest temperature range of the 4 components.... still, that amount that the trans could burp should be fairly minimal. Unless the trans feeder line gets cut and the sending line gets clogged, I can't see the trans pumping up it's own internal pressure. If you're worried, the simple solution is to just T it in near the top of the engine, that gives the fluid splash enough tube to maybe not even make it to the top upon full warm up.

We can estimate the amount of airflow by using the ideal gas law, PV=nRT. We're only worried about volume, V and temperature, T (assuming pressures stay at atmospheric). So V1/T1=V2/T2. We will assume a transmission in winter going from 0 to 200 F (250K to 360k). V1/V2 = T1/T2. The ratio of Temps is approximately 2/3, which equals the volume change. So you will only be flowing around 1/3 of the air volume in the cavity (maybe 1/3 gallon?)... and think of the time it takes to change that much in temperature. We're talking a tiny amount of flow in probably 30 minutes.

I imagine the difference in the breather sizes between the front and rear diff is due to the size of the air pocket in each, the rear diff has the potential to flow more air than the front one does purely due to the differences in volume.

[chevycrew]

I would not tie in to the intake.

You will create a vacuum inside, that will try to pull water into whatever is vented.

[Trail X]

I would not tie in to the intake.

You will create a vacuum inside, that will try to pull water into whatever is vented.

The vacuum before the throttle body is pretty minimal.

[Blackout]

Thank you James. I was just looking at the compnine and exploring a bit more on the OS while everyone was posting up. Found where you're talking for the transmission vents. I already spent the money on the little filters, so I might as well use them for the stuff I already ran. I might hook in the TC with the Differentials and use the existing hose that I already ran for the TC and reroute it to the transmission. I have a fitting already down there from where I ran the rear Dif near the TC I can swap for a T so I can hook the three together and leave the transmission separate. Didn't really realize there was as much chatter on the OS about this as there was before I went ahead and did it. Apparently I didn't look around enough.

I'll keep the power steering in mind as well. Any other suggestions/thoughts?

[HARDTRAILZ]

I have gotten my tranny hot enough to spit fluid out that Mr Barton noticed on his windshield behond me. I would keep it seperate.

[NC_IslandRunner]

Would a tranny cooler help, or would it be a hazard on the trail. Just thinking out loud, I need to move my vent lines to.

[Trail X]

Hide it well from rocks and it can only help in my opinion.

[HARDTRAILZ]

Planning to add one soon.

[rjpoog1989]

I would say that a tranny cooler can only help. I plan to add one soon in an attempt to have my tranny last as long as possible.

[Blackout]

Didn't swap the lines around yet but I made the bracket for the filters.
Crappy quality since the pictures are from my phone

4.5" x 5" 22g aluminum.



Flat black enamal and some self tapping screws later, here's the finished product:

[djthumper]

that looks good.

[HARDTRAILZ]

Well Done