Another 4400 front axle leaking!

[arrabil]

BTW, gear oil is still specced for many many final drives in cars, where
the greatest gear forces are.

I'm pretty sure the clearances on manual trannies that specify ATF are smaller than those in an axle. I don't know of any final drives spec'd for anything but gear oil do you?

Speaking of which.... all automotive axles are vented. I don't think the 4000 series axle is vented. So maybe thats why minimally expanding hydraulic fluid is specified?

 

[captin_insano]

I'm really surprised the axle has no vent on it. The air is what expands when its heated during use and it finds its way out. If you get it in water, or maybe even wash it after use the air cools creating a vacume and it will suck water back in. The milky thick oil someone mentioned earlier was caused by this. I think if I had to do this repair I'd look for a way to put a vent on the axle.

 

[defed]

i was considering looking for a vented type cap for the fill plug. mine leaks erratically now. it leaked 1/2 quart suddenly after sitting idle for 5 days, then none sitting one day (after refilling). i used it alot yesterday, and it was dripping a bit here and there. and when parked, was dripping into the pan i put there to monitor how much leaks.

btw, where do you find the spec number of the axle as listed in jdparts? i read somewhere that it was near the fill plug, but i don't see anything except 'spicer'.

 

[arrabil]

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. You should hear pressure release when removing the axle plug on this front axle. Anywhere air can leak out will be a place the axle oil can leak out. You should definitely not be contaminating the axle with water after washing it. Thats just a sign of already failed parts.

defed, sounds like time for a full axle seal rebuild. 1/2 quart is a lot of leakage.

 

[dfkrug]

I'm pretty sure the clearances on manual trannies that specify ATF are smaller than those in an axle. I don't know of any final drives spec'd for anything but gear oil do you?

Speaking of which.... all automotive axles are vented. I don't think the 4000 series axle is vented. So maybe thats why minimally expanding hydraulic fluid is specified?

Clearances inside manual trannies may be tighter, but the greatest forces
are always in the final drive due to torque multiplication. I know that Honda/
Acura FWDs use 30wt motor oil in their manual trannies, and the tranny
is integrated with the final drive. I suspect that many (most?) FWD cars
have integrated trannies/final drives. I was surprised when I found out
Honda used motor oil (in our long-gone Acura Integra).

As for venting, all the 4x4 tractors I have had were unvented in the front,
regardless of whether gear oil or hyd was specced. Perhaps tractor MFWD
axles are not vented because they are highly exposed to mud or water
above the fill port. If someone wants to try to vent their axle, I suggest
using a protected rubber tube that ends in a higher location. Off roaders
do that for their rear end vents to keep water out of there.

 

[dfkrug]

btw, where do you find the spec number of the axle as listed in jdparts? i read somewhere that it was near the fill plug, but i don't see anything except 'spicer'.

Right here (photo).

On my axle, I could see the date, but not the part #. I had to remove
the paint. This old unit has no manufacturer stamp, but it seems to share
molds with Spicer-marked units on later 4x00s, 4x10s, and 3x20s.

 

[arrabil]

So we've seen gear oil, hydraulic fluid, engine oil, and ATF spec'd for axles.... I really think that means they're all of high enough quality nowadays to use any of them.

If someone wants to try to vent their axle, I suggest
using a protected rubber tube that ends in a higher location. Off roaders
do that for their rear end vents to keep water out of there.

I vent both axles, the transfer case, and the transmission to the hightest point in the engine on my off-roader.

 

[defed]

defed, sounds like time for a full axle seal rebuild. 1/2 quart is a lot of leakage.

i have to call the dealer 1st and see what they will do under a drivetrain warranty. if nothing, i will do at least the one side. probably leave the 2nd side until it starts to leak.

 

[dfkrug]

Yes, oil expands when it gets hot. So much so that the SCCA rule book
requires that gearbox and final drive vents use hoses and remote-mounted
catch reservoirs to avoid getting any oil on the race track.

Certainly, oil in a MFWD axle can get hot under exteme conditions, too.
Apparently, the manufacturers have decided that the axles can withstand
the internal pressures without bad consequences and axle vents would
cause more problems than they solved.

 

[defed]

talked to the dealership today....they will only cover 1/2 the cost, or give me the parts to do it. i was kind of irritated that my 'drive train' warranty wasn't going to cover the full cost. he said...it's a used tractor...i said...but you gave me a 30 hr warranty on the engine and drive train.

so i talked to the service manager about some details of the job...like, do you have to disturb the hub seal to get the shaft (kingpin?) and all that out the bottom plug. he said it can all be removed w/o taking the hub apart, or without removing the shoulder from the axle. it is easier to do the work on the bench, but he said it's a pain to get the shoulder back onto the axle, so he just does it on the tractor. so it sounds like i don't HAVE to do the hub seal to do the shoulder/knuckle seal. if they will give me the parts to do both, i will. if not, i might just wait until the hub seal leaks. the hub seal seems alot easier to do at any time....except for the fact of draining and cleaning everything twice...maybe i'll just do both! he said i could borrow their spanner wrench for the nut.

btw, i was quoted $400 to replace it. i'd have to pay $200. think i will do it myself.

 

[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.