Dana 44 venting lube??

[phred]

My front axle housing is pushing lube out the vent tube. The vent hose/tube is long and loops up to the cowl so there has to be a fair amount of pressure to push lube up 3 feet. The hubs are unlocked and t-case is in 2 hi. I’ve double checked that the driveshaft is not turning. Anytime I drive more than 10 miles the vent tube drips lube. What is causing the housing to pressurize?

 

[FordBronc]

Are you using 80/90 gear lube? What is the fluid level, in the cold state? Normal or high to the ck/fill plug edge? Does the diff cover feel warm to the touch when it burps fluid?

 

[phred]

80w90 lube, diff is cold, fluid level is just below the fill plug. It’s crazy odd. I’ve checked everything that I can think of.

 

[Yeller]

That’s quite the conundrum. I throw out some more nonsense that may help or may just make more mud….

Vent in original location on the diff?

Never seen it on a front that was running unlocked, but have seen it often in front diffs reworked and turned into rear’s using the factory vent location. The oil would cover the vent hole with a film of oil and then as it would heat up push oil out the tube. Wound up taking a piece of copper tube with holes drilled into it inserted through the vent fitting into the diff to create multiple paths for the air to escape solved the issue. The tube stuck into the diff about 1-1/2”. The tube was retained with a drilled out compression fitting so the tube would slide all the way through and be retained by the feral and nut.

But that still is weird. The only thing I can think of is the same scenario caused by parasitic drag through the transfer case while driving at speed and it enough to replicate the above scenario but not make the diff warm to the touch. Like I said no idea just throwing something out there that might stick.

 

[FordBronc]

Ok so another question, is the front axle all stock? Or have you had or done yourself any internal work to it? Like different gears, locker, seals replaced recently?

 

[phred]

Steve, the vent hole is in the stock location. I extended the hose up high as a precaution against water intrusion.
I too think there must be some drag on the t case causing the drive shaft to spin even out of gear. I’ve put some long zip ties around the shaft hoping to hear it slap the body if it is actually spinning.

FordBronc, the internals are not stock. 456 gears, Eaton e locker, up graded carrier etc. everything in and on that housing is new. The entire drivetrain only has 1200 miles on it. This venting is intermittent.
The first couple time it did it I figured it was over filled, but I checked and ruled that out. I also ran the front with the hubs lock for about 20 miles to temper the new gear set but even then it still shouldn’t vent. It’s not a lot I’ve lube at any one time maybe 2-3 oz but enough to make a mess and cause concern that something isn’t right.

 

[FordBronc]

Well I am out of good guess's then, with the diff cover not warm to the touch, and the fluid level correct. A couple more questions.

Is the end of the hose cut straight or at an angle? Do you have one of them vent line mini air filters on it?

Unless adding the extra length rubber hose and where ever the end ends up placement wise (high on the core support or inner fenderwell). Is it possibly causing some sort of vacuum as you drive it and air passes thru the engine compartment? I know CrAzY idea.

What about taking the added length off and drive it with the normal length vent hose and see what happens?

Guess you need to put the end of the tube in a vented catch can to prevent a mess.

 

[904Bronco]

Is it a factory D44 cover?
I ask as I have taken apart a unit with chrome cover that had the drain plug lower than the factory cover. It would not take the factory specified amount of gear oil. It got changed out.
Had the opposite, where a unit had a fancy cover that the cover had the fill hole higher, so it took more fluid. If that is the case, maybe you have too much fluid?
Just a random thought...

 

[phred]

Well I am out of good guess's then, with the diff cover not warm to the touch, and the fluid level correct. A couple more questions.

Is the end of the hose cut straight or at an angle? Do you have one of them vent line mini air filters on it?

Unless adding the extra length rubber hose and where ever the end ends up placement wise (high on the core support or inner fenderwell). Is it possibly causing some sort of vacuum as you drive it and air passes thru the engine compartment? I know CrAzY idea.

What about taking the added length off and drive it with the normal length vent hose and see what happens?

Guess you need to put the end of the tube in a vented catch can to prevent a mess.

Vent tube almost vertical and is strapped below the hydroboost unit. We though abou the vacuum issue but there shouldn’t be any high pressure air at that location.

 

[phred]

Is it a factory D44 cover?
I ask as I have taken apart a unit with chrome cover that had the drain plug lower than the factory cover. It would not take the factory specified amount of gear oil. It got changed out.
Had the opposite, where a unit had a fancy cover that the cover had the fill hole higher, so it took more fluid. If that is the case, maybe you have too much fluid?
Just a random thought...

Good point. Not a stock cover. Heavy steel cover. I’ll check the fill plug locations and see if they match!!!

 

[DirtDonk]

Since you’re not off roading with this thing yet and dirt or water getting into the differential is not a huge concern at the moment (it sounds like at least), try disconnecting the vent tube from the vent tube fitting and driving around.
Just to make sure how much is coming out of the differential at any moment, rather than any built-up in the tube.
If the tube is full, obviously this will make a mess as it drains down so have a pan ready. But any mess coming out of just the vent fitting will be easy enough to clean off the differential as you are testing.

This is just for testing and to eliminate any other variables. I can’t think of anything that an E-locker can introduce into the system that would cause it. It’s not like it’s an ARB where compressed air might leak into the system.

 

[phred]

Ok. Just pulled the old diff cover off the shelf and the fill hole on the new one is about 3/4” higher. So I’m gonna guess it over filled I’ll try and siphon some out and see if it solves the problem. Thanks for all the ideas!!!!

 

[Yeller]

or install one of these and not worry about it

 

[Broncobowsher]

Hubs UNlockd and in 2WD? There should be no rotation of the parts. Maybe a hint of parasitic drag rotation, but with fresh gears and good preload on the bearings I doubt even that. really the only heat that would get into that front diff is what is radiated off the engine. No rotational splash, only splash from shaking of the axle.

The vent hose, does it have ANY dips in it? Dips can hold fluids and be pushed out from a warming air pocket behind it.
Are there any other vent lines in the same place? Any chance that one of those is spitting oil over to this one?

 

[phred]

Yeah it’s definitely in 2wd and hubs unlock. Vent line has no unreasonable dips to trap lube. I’m gonna pull the vent hose off and drain it as well as siphon some lube out.

 

[jamesroney]

Yeah it’s definitely in 2wd and hubs unlock. Vent line has no unreasonable dips to trap lube. I’m gonna pull the vent hose off and drain it as well as siphon some lube out.

The vent hole in the factory retaining bolt has a tiny little hole in it. The theory is that it will never get oil past it, so it just needs to vent AIR. Your Eaton e-locker is a full case differential. When it spins, the body acts as a slinger, and once the oil gets slung near the tiny orifice, capillary action draws it into the hose. Subsequent thermal cycling pushes the oil up the hose.

I had a D44 HP in a TJ that had the same issue. It was a puker. The oil in the hose could never drain past the port in the fitting. So it acted like a check valve, and dribbled all the time. I had an ARB, but the slinging effect was similar. Worse, with my ARB, the seals leaked, so if you engaged the locker, it would cough up whatever was in the hose. That's how I knew that the hose was full. And yes, it had the same problem when I disconnected the ARB hose.

If you want to do something interesting, replace the hose with clear tubing. Then you will see it work its way up and out. Or just do what @Yeller recommends. A ported tube in the fitting is a brilliant solution. Also you can open up the tiny hole in the fitting to allow drain back.

Just take some comfort in knowing that it isn't you, and you are not going crazy. I spent at least 6 months "not fixing" mine.

 

[Yeller]

Those accordion looking contraptions are what we run on the comp cars, no leaks if it gets dumped upside down and sits there for a bit and keeps the seals happy. Street driving on the rear they aren't large enough volume but on a front usually work fine.

 

[phred]

Well it was over full. Stupid me. The heavy steel diff cover full hole is higher than the vent hole. (Why?!). I pulled the vent hose and the fitting and let the excess oil out. That should solve it
Another lesson to never trust aftermarket stuff to be exact.

 

[Yeller]

That’ll do it. Glad it wound up being simple. It was making my head hurt almost as much as yours lol