Lube FRT/DIFF blowing out fo vent on highway.

[DA BIG ONE]

Changed out my seals on the front differential, after running at 60+ mph for about 30 minutes diff lube blows out of vent. Drive around town and it does not do this.

This issue started back about 1 year ago when I had an ARB locker installed and nightmares began. On very first trip after arb install lube blew over everything from vent, they put on larger vent that did not fix it. Did not blow through vent for awhile because axle flange seal failed. Now that seals are new this pressure buildup, or?, rears it's ugly face.

Someone suggested lash maybe too tight heating case causing pressure, but case is warm to the touch.

The front differential is new, vent is clear, lube is synthetic, but was taken apart to change out gears, then pulled apart of the ARB, then for the ARB again when they though they installed the seals to the airlocker wrong, or?

Thinking I'm going to install a vented catch can for now, but I need to get this fixed.

[BobND]

This is when you are highway driving under conditions where the CAD can be locked in, right?

My 1994, a friend' 1994, and my son's 1991 will ALL **** SOME gear oil out the vent, if run as hard as possible, with the CAD locked, on questionable, partially icy highways. Never have figured out why.

[BobND]

This site's potty filter must not like "ekup" (backwards), and subbed ****!

[DA BIG ONE]

Originally posted by BobND:
This is when you are highway driving under conditions where the CAD can be locked in, right?

My 1994, a friend' 1994, and my son's 1991 will ALL **** SOME gear oil out the vent, if run as hard as possible, with the CAD locked, on questionable, partially icy highways. Never have figured out why. Nope, CAD is disengaged, air locker and compressor off. This is more than just a little lube here, so much so I'm installing a vented catch can to save lube and route it somehow back to diff.

I'm running 75/90 weight lube someone suggested it might be too thin, or?

[twaddle]

Hi there,
The oil is not too thin even when warm as it is a 90 sae spec when warm the 75W just means it is the equivilent of 75sae at winter temperatures to put it simply.

What kind of vent set up is it? Is it just a small vent cap or a long tube that goes up to the bulk head at the back of the engine.

If it is not the tube type you might want to try this as it would allow for heat expansion of the air space but give the oil somewhere to go and return to the diff when cooling down.

The other option is make up some kind of spash guard that would stop the oil from splashing or being thrown towards the vent hole on the inside of the diff housing.

Good luck

Jim Twaddle
Biggar, Scotland

[DA BIG ONE]

Originally posted by twaddle:
Hi there,
The oil is not too thin even when warm as it is a 90 sae spec when warm the 75W just means it is the equivilent of 75sae at winter temperatures to put it simply.

What kind of vent set up is it? Is it just a small vent cap or a long tube that goes up to the bulk head at the back of the engine.

If it is not the tube type you might want to try this as it would allow for heat expansion of the air space but give the oil somewhere to go and return to the diff when cooling down.

The other option is make up some kind of spash guard that would stop the oil from splashing or being thrown towards the vent hole on the inside of the diff housing.

Good luck

Jim Twaddle
Biggar, Scotland Hello JT, Thanks for your response & question.

This is the front differential and it has a good sized vent at the top of the pumpkin w/tube running up to top of radiator support then capped off w/fitting that prevents water from getting into it during fording, or running in deep water on roadway.

I had tried a larger vent tube, to no avail.

The air locker air feed line from the compressor has a purge valve that is set to 4 psi to purge any differential pressure, so I'm guessing the pressure is going way beyond that psi level.

There is no splash shield that I know of because front gears are reverse cut and do not, or are not supposed to throw oil up at the vent.

I'm going to monitor temps at differential, but yesterday after the run and about 15 minutes the pumpkin was only luke warm to the touch, doubtful it would cool down that quickly if heat was the issue, but who knows?

[rjschoolcraft]

On these IFS diffs when they are disengaged, the spider gears are turning all the time, driven by the left axle shaft. The right side output shaft from the carrier is spinning backward while the axle spins forward. To engage four wheel drive, the transfer case must engage first to start turning the carrier. This will slow the spider gears down to a stop (if travelling straight) which will cause the right side output shaft to decelerate, pass through zero speed and accelerate up to the speed of the right axle, allowing the shift collar synchronizer to engage and drive torque through. That's why it is not a good idea to engage four wheel drive during a turning maneuver.

If the front diff is really disengaged, the churning caused by the spider gears should not be enough to cause the problem you're describing. I had a problem like that once when the front axle did not disengage and the oil level was low. The heat generated (because of inadequate cooling from low oil level) caused an increase in pressure inside the case and pushed oil out the vent.

Double check your oil level. I'd also make sure that the front axle is, indeed, disengaging completely.

[MTTwister]

The air locker air feed line from the compressor has a purge valve that is set to 4 psi to purge any differential pressure, so I'm guessing the pressure is going way beyond that psi level.

Based on ronniejoe's description of pressure build-up, are you SURE that the valve is indeed purging at 4psi?

Good Luck!

[JohnC]

I don't understand how you can have any pressure in the housing unless either the vent is somehow obstructed or there is a *massive* influx of pressurized air...

First thing I'd look for is a dip in the vent line that would allow oil to puddle up and obstruct the vent. Then I'd look for a pressure leak...

[kaylabryn]

I am curious, the statement about the compressor line purging diff pressure when above 4psi. The line from the compressor I would think should never see diff pressure. I would be curious if compressor pressure is getting into the diff. Or like JohnC said check the vent tube for kinks or dips.

[DA BIG ONE]

Originally posted by ronniejoe:

Double check your oil level. I'd also make sure that the front axle is, indeed, disengaging completely. Hello RJ, I had just filled the diff when I reinstalled it about a week ago.

As for the axle disengagement, the steering wheel does not bind whne turned to lock when in 2wd, but will bind in 4wd hi, 4wd low, and sometimes when autotrac is engaged.

[DA BIG ONE]

Originally posted by JohnC:
I don't understand how you can have any pressure in the housing unless either the vent is somehow obstructed or there is a *massive* influx of pressurized air...

First thing I'd look for is a dip in the vent line that would allow oil to puddle up and obstruct the vent. Then I'd look for a pressure leak... No kinked vents, or dips and they are clear.

Air compressor is off so there would be no pressure in lines.

[DA BIG ONE]

Originally posted by MTTwister:
The air locker air feed line from the compressor has a purge valve that is set to 4 psi to purge any differential pressure, so I'm guessing the pressure is going way beyond that psi level.

Based on ronniejoe's description of pressure build-up, are you SURE that the valve is indeed purging at 4psi?

Good Luck! Factory tech says 4psi purge is set at factory and only works when air compressor is off, guessing I can test it. When compressor is on the valve is bypassed. I can't get a straight answer about why the purge valve is needed with system off.

[azblazor]

I think the 4 psi purge is to prevent heat from pressurizing the Air line to the locker and causing it to engage when not called for.

[DA BIG ONE]

Turns out seal housing 1st series on ARB carrier is acting like a hydro pump creating the pressure and pumping the lube according to their tech. They are sending me all new updated parts to correct the problem.

This same carrier is also used in 2003 and newer ram charger solid front axles, dodge claims it's actually stronger than the dana 60 it replaced.

I'm going to see if I can get this front differential apart and find a good machine shop to pull bearing off of carrier, install the updated parts then press it back together so I can reinstall carrier back in diff.

Hopin I don't screw up!