Another 4400 front axle leaking!

[defed]

scraped down the paint behind the fill tube....S20BZ107.

 

[dfkrug]

scraped down the paint behind the fill tube....S20BZ107.

The 107s and 109s use the same #14 nut, while the 103 and 105 axles
use what the parts book calls a "retainer" instead. Mine is a 109 with
2-sided PS cylinder; I think yours has a one-sided cyl with tie rod.

 

[defed]

yes, that is correct. the service guy told me it was the newer style axle.

 

[defed]

how come they don't list the special wrench under the 'special tools' section of the service book? my dad says he has several wrenches at work that might work, but if i can't find out the details of the 'deere' wrench, i don't know what i need.

the dealer said i could use theirs for the wkend, but might be easier to use another one that i don't have to rush back if things don't go well.

is this special nut the one they are referring to when they say "torque prevailing nut"? it's the only nut there, and they say not to re-use it. or...is that a difference in axle models...like the torque prevailing nut in the hub, that isn't there in my axle (snap ring instead).

 

[captin_insano]

Gear oil very much does expand. Around 10% at higher working temps. The air pressurizes significantly while the gear oil does not. Neither should find their way out of the axle while running.

To be technical, the oil, steel and air obviously all expand. However the air expands the greatest amount and plays the largest role in pressure changes in the diff. I've never seen an axle with a real pressure type seal like you find in hydraulics so assuming they dont have them the pressure will certinally normalize to some degree. The good can go out and the bad can come in.

 

[arrabil]

I've never seen an axle with a real pressure type seal like you find in hydraulics

That is because we're not working in the thousands of psi. Or even tens or hundreds.

The good can go out and the bad can come in.

On its own, this is against the laws of physics. If the higher pressure is inside the axle, pressure release can only occur to the outside of the axle. The only way for anything outside of the axle to makes its way into the axle is if the axle is at equal pressure or lower compared to the outside (and the seal is no longer functioning in some manner).

Submerging the axle into mud/water, and spinning the tires to cause a super high pressure buildup past the capacity of the seals, can cause so much pressure release that it becomes a minor (and temporary) vacuum and sucks mud/water back in to equalize but that is the only scenario I've ever heard of where an axle in good condition takes anything in. And at that point the seals have been ruined from the pressure buildup and release or they would hold the vacuum if they could.

 

[defed]

did my seal today. wasn't too bad. left the shoulder mounted to the axle. was actually easier taking it apart that putting back together, because once the snaps rings are out, everything drops down...putting back together, nothing stays up! hardest part was putting the knuckle back onto the shoulder. needed 2 ppl. there was a small burr on the upper sleeve, i used a fine file and cleaned it up. i could have replaced it, but the rest of it looked brand new. need to scrounge up some better seal drivers for next time, and find (or make) a spanner socket for my toolbox.

i didn't do the hub seal as i had intended. the dealer told me that some front seal work had been done when it was brought in for trade. but the description of the work was cryptic. after i had it apart, it appeared that someone had been in the hub area, so i presumed they did it. worse case i have to pull it apart again to do it when it starts to leak.

let's hope they all hold their oil for many years.

 

[captin_insano]

On its own, this is against the laws of physics. If the higher pressure is inside the axle, pressure release can only occur to the outside of the axle. The only way for anything outside of the axle to makes its way into the axle is if the axle is at equal pressure or lower compared to the outside (and the seal is no longer functioning in some manner).

Its quite obvious that these things wont move from a lower to higher pressure gradient. But as you mention they do move from higher to lower. As if I need to point that out. So what happens when the axle gets hot, the pressure leaks off and then you cool the hot axle by washing it or submerging it in mud/water. You create a higher pressure on the outside allowing the water and slop to come in. A normal bearing type seal will not hold much pressure, especially with some hours on it and you can get water and crap in past the seals.

As a side note my last kubota had a vent and its axle was dry as a popcorn fart when I got rid of it with 220 hours. The oil was like new when I changed it. My new kubota has 9 hours and these threads made me go look at it. No vent on the new one and its wet already on both sides where the portal bolts to the housing. Looks to be a machined surface with no gaskets or seals and is probably leaking slowly when the axles under pressure. Oil leaks irritate the crap out of me so I think its time to vent it.

 

[arrabil]

So what happens when the axle gets hot, the pressure leaks off

If this actually happened on a regular basis you would never hear the hiss when opening the axle.

A normal bearing type seal will not hold much pressure

Since you do hear the hiss every time you open the axle the seals must successfully be holding in the pressure.

cool the hot axle

Cooling the axle to the point of generating a lower pressure inside it than outside would require WAY more than washing it with some water. To raise the pressure the axle temperature goes up 100 degrees over outside temperature. To lower it equivalently you'd need to lower it 100 degrees. Since you create the heat inside the axle it travels towards the outside. But to cool it from the outside you need the cold to travel towards the inside. I'm thinking you'd need to dunk the whole axle in dry ice for an hour to get all the oil to swing 200 degrees.

You create a higher pressure on the outside

You have the ability to make localized changes to atmospheric pressure!?!? I totally need to know how you are "creating higher pressure on the outside" with soap and water.

Looks to be a machined surface with no gaskets or seals

Seriously?

 

[RoyJackson]

Interesting discussion. The MFWD on my 870 requires JD GL-5 gear lube. I wonder what changed over the years now that Lo-Vis Hygard is called for.

Same thing for my 2003 790. The 3005 (new designation for the 790) also requires GL-5 (80-90 weight). Maybe that's why these axles are vented and the old 4xxx series (and newer replacement models) aren't vented.

arrabil, you were right (response to a comment you had in another thread about leaking front axles). I checked my buddy's 4300 and it dd not have vents.

I like the heavier weight gear oils as they do provide outstanding lubricity in heavy loading situations. However, as one of you posted previously, a lot of automotive and light truck manual transmissions use ATF. My 1997 Ranger did...my 2005 Nissan Frontier uses 75-85 weight gear oil.