Venting the front axle on CUTs(with pics)

[arrabil]

1. you cannot have any loops or low hanging bends in the line since oil would pool there and could stop oil from leaking back into the axle if it were looped enough. Kind of like what plumbers put under sinks (water trap)

Quite right. I'm already there....

2. with an expansion tank, IF you ran across a situation that pushed oil up into the tank while using it, the internal heating of air could for a pressure in the axle and could not allow the oil to drain back into the axle for some time. It would require a pressure drop or for the air to escape past the oil up the tube. A larger diameter tube would solve this issue.

Totally agree. How large of a diameter tube is the question then. I'm using 3/8" ID I believe. You think thats fat enough?

Might have Spicer or JD seen this problem with there engineering studies and said the axle is better off with a little air pressure or did they take the easy way out?

They really didn't leave near as much expansion room in the axle as would be necessary to vent it. The Ford axles I normally deal with have almost the same fluid capacity specifications but have four times the expansion room. They could have vented it at the top of the pumpkin and solved all these problems. I heard of a lot of axle seal leaks on the 42/43/4400 specifically and not other models. I wonder if the axle housing got bigger in the newer models?

It should then allow air out when the pressure builds but keep the oil in.

You think? I think the oil will come out too. Otherwise why did they even put an o-ring in there?

With no disrespect, we don't even know if the seals failing is due to no vent.

Well this is something I'm fairly confident of. There is a LOT of pressure in the axle. I think more than the seals are designed to handle long-term considering they get abused pretty good under normal tractor usage.

 

[nmu98]

Arrabil,
I have no clue what size hose would work. I was just talking out loud.

Your right, by removing the rubber o-ring you might drop some oil, but I would think that the viscosity of the oil would tend to keep all but seepage in the axle? But you never know.

I have has 2 3720's now and never had an issue with either one. I will watch the new tractor we have coming and check to see if I can let air out of the axle after use, especially during the break in period.

I wish you guys luck!:thumbsup:

 

[arrabil]

I have no clue what size hose would work. I was just talking out loud.

Hey, so am I. I'm still gonna try a small expansion tank with the hose I already have. No point in stopping within sight of the finish line. If it works, great, if not, at least something was learned.

 

[arrabil]

Well duh. I already have an answer as to whether 3/8" is fat enough. No, of course not. Otherwise the oil wouldn't be in the filter in my pictures! And there wouldn't have been anything to drain.

Thats a shame.... I just found an expansion tank in my trash can.... the fuel tank from a broken, 10 year old Ryobi trimmer I took apart a couple months ago.

I'm going to give this some more thought. A day or two until I get my seat back on the tractor anyway. But I think I'm going back to the sealed axle pending any light bulbs from anyone.

 

[Rob-D]

Doesn't seem to be a problem for me!:thumbsup:

There are times the water will be above the axle.



Very true. Vented case has no inside pressure. Height of water has pressure. Physics.:thumbsup:

Water above the axle won't do it. We went through that already.

"Height of water has pressure."

Yes, Physics. 4.6 feet of head = 2 lbs of pressure. Exactly where are you driving your boat?

 

[Rob-D]

msmud, I've noticed the same thing. I suppose in time, as the seal wears it may not be able to contain the pressure build up, and would start leaking. The pressure build up on my only occurs after working it a bit, but it's there to be sure.

Here's the other thing. Look back at my explanation of watches. Watches draw dirt in as the gas contracts. In a tractor with a sealed case you have the same problem, as the case cools it draws the dirt around the seals in. You constantly have this on going on a daily basis.

Rob

 

[Rob-D]

I applaud you guys for working to solve a possible problem with the front axles. It sure seems that JD has sealed these for a reason. Possible due to the same problem that Arrabil has, getting fluid out his vent hose.

Now correct me if I am wrong on this. If you add a single vent hose and run it to a tank:
1. you cannot have any loops or low hanging bends in the line since oil would pool there and could stop oil from leaking back into the axle if it were looped enough. Kind of like what plumbers put under sinks (water trap)
2. with an expansion tank, IF you ran across a situation that pushed oil up into the tank while using it, the internal heating of air could for a pressure in the axle and could not allow the oil to drain back into the axle for some time. It would require a pressure drop or for the air to escape past the oil up the tube. A larger diameter tube would solve this issue. Would the amount of oil pushed up the tube have any negative consequence on the axle?

Might have Spicer or JD seen this problem with there engineering studies and said the axle is better off with a little air pressure or did they take the easy way out?

Might you be able to get a fairly vented yet mostly sealed axle by just removing the rubber o ring on the fill/dipstick? It should then allow air out when the pressure builds but keep the oil in. The question is what is stronger and tighter the seals or the cap without the o-ring.

I think this is great stuff, but if rob was cutting a hill side and pumped all the lube, or a lot of lube out his breather, that would suck a lot more than a possible seal leak. With no disrespect, we don't even know if the seals failing is due to no vent.:confused2:

First it's not the seals failing but the lack of breathability certainly adds to that. The problem is oil being blown out the sealsas the air expands from heat.
Just leaving an open hole would allow small amounts of dirt to enter the case, although very little as I see it.

The other thing is this. The air in the case is breathing as temps go up and down but very little. You may be on the side of a hill but if there is no appreciable pressure in the case than no oil will escape. As the oil gets bounced around in the case the vent will expel or draw in air so the pressure should be low.

What will happen is that I will check the box as I use it today and see if the level goes down. or there is oil on the outside of the housing.

Rob

 

[Rob-D]

Arrabil,
I have no clue what size hose would work. I was just talking out loud.

Your right, by removing the rubber o-ring you might drop some oil, but I would think that the viscosity of the oil would tend to keep all but seepage in the axle? But you never know.

I have has 2 3720's now and never had an issue with either one. I will watch the new tractor we have coming and check to see if I can let air out of the axle after use, especially during the break in period.

I wish you guys luck!:thumbsup:

My 3320 has a good deal of pressure when I check it at the end of the day. Check it hot, once it cools down air is drawn through the seals to equalize the pressure.

 

[Rob-D]

I did exactly that. I pointed it out to you in April. You must have forgot.

Either way... the problem is air and oil expansion as reposted by nmu98 from the thread I started on the subject. I'm going to add an overflow container if I can find one small enough. Maybe from a motorcycle or a small Deere.

I'm not sure what was going on with your system. You may very well be correct that the expansion pushed the oil up the the tube to the filter. But why? Were you working on a hill with the oil clogging the vent? Ok, you had to be doing this for a good stretch tothe point where the pressure built and no air could reach the vent. Let's see what happens with my tractor. I just filled the axle.

Whatever we finally do it has to be better than the current desing with an unvented case drawing dirt though the seals back in the tranny.

Rob

 

[Rob-D]

Good debate guys!

Rob