Differential breather routing?

[justinhw]

I've seen quite a few pictures with diff breather lines extended and routed to the air intake. I figured that it was to prevent water entry during water fording, keep debris out of the diff, etc.

Recently though I've been considering ARB air lockers, and have been reading up about pressure inside the diff.

Question: Does routing the diff breather lines up to the air intake result in a slight vacuum being pulled? Does this effect the diff pressure significantly?

I can also imagine a situation where the slight vacuum would clear the line of fluid that may get plugged in the line regularly. Is this a benefit worth considering?

Thanks!

 

[Hill Bill E.]

I wouldn't do it. Never heard of it myself, but I can't see putting a vacuum to any driveline breather.

It has the possibility of sucking water or dirt into the diff/tranny/T-case.

Granted, the intake probably wouldn't create enough vacuum, but I personally wouldn't take the chance.


I have heard of guys pressurizing the breathers, with a low pressure, to prevent water from coming in, but never heard of doing the opposite.

 

[OTR]

I just extended mine up into the rear taillight area, actually behind the taillight. Very simple mod.

 

[ntsqd]

Both axle breathers on Patch were extended into the engine bay where there is a dedicated fluid/air separator and a breather filter.

I'll second not putting the axles under any vacuum. A couple psi of pressure would be a better idea if cold water crossings are normal for you. I would be inclined to set up the system to breathe freely until such a crossing, then be pressurized only as long as needed.

 

[CanuckMariner/Nomad]

If you are going to do a lot of water crossings and your diffs and transfer case/trani are going to be submerged often, getting all the breathers to higher elevation is a good thing. Water in any of these will cause considerable havoc and be expensive to fix.

I have my both my diff breathers going up to respective corners of my engine bay. Then I T'd my transfer case/trani breathers into these tubes respectively. I used the stock check valves from these breathers and attached them to the top of the hose/tubes in the engine bay. It is rare that I ever go deep enough into the water that these points submerge.:costumed-smiley-007

 

[rusty_tlc]

If you do a single water crossing you should drain and replace the gear lube.
Hot Diff + Cold Water=> can pull water in through the stock breather. Especially since the breather check valve is probably dysfunctional on any truck that sees much dirt and mud.


The cost of extending the breather is a lot less than the cost of changing the gear lube even once.


Simple decision IMHO.


My F&R Diff's and T-case are all plumbed to a single check valve under the hood on the firewall. I didn't bother much with a filter because I use cheap oil and change it often.

 

[eugene]

Both axle breathers on Patch were extended into the engine bay where there is a dedicated fluid/air separator and a breather filter.

What did you use for the fluid/air seperatror, somehting used for an air compressor, or something made for specifically for this purpose? Are all the lines connected together into one?

 

[01tundra]

I have my front differential, transmission, and transfer case all routed up to top of the front fenders in the engine compartment. I have the rear differential routed up to the top of my bed.

All vents are individually terminated with N.E.X.T. vents to avoid possible cross-contamination of fluids -

http://northeastxt.com/vent.html

 

[overlander]

I have an extended breather kit, so both diffs, T-case and tranny all have stock breathers replaced with lines that all join in a manifold in my engine bay, then the manifold has a single line that extends to the top of my snorkel. Deep fording is rare, but nice to know it's in place when the time does come. usually unexpected. I consider it, and the snorkel, cheap insurance. We are in the middle of hurricane season!

when breathers get plugged, and the diff warms up, the internal pressure pushes oil out past the axle seals. that's the first thing to check for when oil is seen running down the wheels.

vacuum would be worse, as it would pull in water, and other contaminents. it would also potentially pull gear oil up into your vacuum source. that's not good.

 

[ntsqd]

What did you use for the fluid/air seperatror, something used for an air compressor, or something made for specifically for this purpose? Are all the lines connected together into one?

Something that I built for another vehicle's engine vent system that didn't solve the problem. So I re-purposed it for axle, trans & t/c venting though so far only the axles are connected. It is not exactly like below, but below is representative of it. They are extremely easy to build.

 

[jesusgatos]

I have heard of guys pressurizing the breathers, with a low pressure, to prevent water from coming in, but never heard of doing the opposite.

That's exactly what I'm planning on doing.

I've extended the vent lines on a lot of different vehicles, and one thing I'd recommend is avoiding running the ventlines down long horizontal stretches if at all possible (like, from the rear axle, up to the firewall). The ventlines tend to accumulate junk in those horizontal stretches, and can get plugged-up pretty easily.

 

[Tony LEE]

I've extended the vent lines on a lot of different vehicles, and one thing I'd recommend is avoiding running the ventlines down long horizontal stretches if at all possible (like, from the rear axle, up to the firewall). The ventlines tend to accumulate junk in those horizontal stretches, and can get plugged-up pretty easily.

Agreed - and teeing off may not be a good idea either. Recently found one of my fuel tank breathers blocked near the tee from the gearbox. Looked like solidified oil. Cleared pretty easily by flushing the line with a bit of diesel, but as it was, it wouldn't have been doing much good as a breather.

 

[R_Lefebvre]

Interesting and timely discussion as I'm just redoing the vent system on my truck. I'm in the middle of changing from auto to manual because my auto got water in it and died. Anyway, I'm reworking the vent system. I attempted to seal up the bellhousing, and tapped it for a vent line as well. So I've got the BH, trans and TC all Tee'd together, and was going to run that line up to the intake box, which is equiped with a snorkel. I was going to just plumb the line to terminate in the box with a bulkhead fitting, rather than actually running it up the snorkel. But now I wonder?

Do people think the box has any meaningful amount of vaccum?

I'm interested in doing the pressurization thing, but haven't seen a pressure regulator that is capable of reliably delivering 1 psi.

 

[jesusgatos]

Agreed - and teeing off may not be a good idea either. Recently found one of my fuel tank breathers blocked near the tee from the gearbox. Looked like solidified oil. Cleared pretty easily by flushing the line with a bit of diesel, but as it was, it wouldn't have been doing much good as a breather.

That's exactly what I found in one of my old vehicles. On Mah deuce, I can't get around those long horizontal stretches, and I will be Teeing lines together, but I'm also going to install fittings at the end of each line that will allow me to blow the lines out with the flip of a switch.

Interesting and timely discussion as I'm just redoing the vent system on my truck. I'm in the middle of changing from auto to manual because my auto got water in it and died. Anyway, I'm reworking the vent system. I attempted to seal up the bellhousing, and tapped it for a vent line as well. So I've got the BH, trans and TC all Tee'd together, and was going to run that line up to the intake box, which is equiped with a snorkel. I was going to just plumb the line to terminate in the box with a bulkhead fitting, rather than actually running it up the snorkel. But now I wonder?

Do people think the box has any meaningful amount of vaccum?

I'm interested in doing the pressurization thing, but haven't seen a pressure regulator that is capable of reliably delivering 1 psi.

Terminate in what box? Not sure what would be creating vaccum.

The military pressurized drivetrain components at 2-3psi, and I know that someone has posted a source for an appropriate regulator on the steelsoldiers forum.

[ame="http://www.youtube.com/watch?v=ICKLGYs8CE8"]YouTube- m35a2 deuce under water[/ame]

 

[Hill Bill E.]

I've extended the vent lines on a lot of different vehicles, and one thing I'd recommend is avoiding running the ventlines down long horizontal stretches if at all possible (like, from the rear axle, up to the firewall). The ventlines tend to accumulate junk in those horizontal stretches, and can get plugged-up pretty easily.

Agreed, been there, done that, and it didn't work well:Wow1: (I hate replacing axle seals!)

Another thing to consider, in any modified part, like a clocked transfer case, or rotated diff, is the 'fill line'

When I clocked my D300 T-case, it also brought the fill plug way up.

It took some trial and error, to find the proper 'new' fill level.

I had installed a sight tube, to see where the gear oil level was, but wasn't sure how much to put in.

I started with the same amount as it took in the stock oreintation, but it was too much.

The result? Gear oil was blown out of the breather tube!! Not only did this make a mess all over the firewall, but it filled the little end cap full of gear oil, which then picked up dust, and plugged.:Wow1: