Venting the front axle on CUTs(with pics)

[Rob-D]

When I sold my last tractor the new owner said the front axle was dry! Yikes! I only had 100 or so hours on it, how could that be? When I got the new tractor I tested my theory that the front axles build up pressure from heat and it pushes the oil through the seals. (I found the same problem on my friends 990 (now the 4005) and we added a quart of 90 weight gear oil to it.
Time to make a vent:
I wanted something that would allow me to still use the dipstick and I didn't want to drill a separate hole in the casing for the vent so I incorporated the vent into the existing dipstick. I also didn't want it to stick out too far and get accidently hit by branches or rocks.

First I drilled a hole through the dipstick (photo 1) with an 1/8 inch drill. Then I machined out the end of the dipstick and tapped it to 5/16-24. I then made the plug out of 2024-T6 aluminum and filled it with material from an N95 breathing mask. ( I made a little punch to give me round padding that I packed into the plug. Lastly I put a gasket on it and screwed it in, then blew through the dipstick to make sure it could breath before I put it in the tractor. Walaaa! It works great and after several hours of work my front axle has no pressure build up.

Rob

 

[Rob-D]

The final version has the tube closed off and two holes drilled at the top of the tube by the thread.

Rob

 

[Egon]

Do you ever drive in water?

 

[nmu98]

I think you have a good idea, but I don't feel that tapping the plastic and drilling holes in the top of it is a good idea. Why not find a dipstick like the ones used on rotary cutters that already have the vent built in and use that? You could easily cut one of them tot he right length and mark your full line. Then it would be protected from rain, snow, and garden hose water when you wash it. I would never leave that open on a tractor, even dust would be able to get in there easily with temperature changes.....

I guess I feel that you have the potential to hurt more than you do help. Good idea, it just needs some adjustment.

 

[Rob-D]

Do you ever drive in water?

Sure but so do you. The tranny on your tractor is vented along with every car you ever drove. In fact most have no filter system just a vent in a cap.

 

[jimgerken]

I like it Rob! Thanks!

 

[Rob-D]

I think you have a good idea, but I don't feel that tapping the plastic and drilling holes in the top of it is a good idea. Why not find a dipstick like the ones used on rotary cutters that already have the vent built in and use that? You could easily cut one of them tot he right length and mark your full line. Then it would be protected from rain, snow, and garden hose water when you wash it. I would never leave that open on a tractor, even dust would be able to get in there easily with temperature changes.....

I guess I feel that you have the potential to hurt more than you do help. Good idea, it just needs some adjustment.

There's nothing wrong with tapping plastic. The plug itself is threaded and fits in the axle case. The plug in the cap has less chance of coming out than the dipstick itself.

Snow and rain aren't going to affect it one bit any more than they affect your tranny which is vented.
Did you ever rebuild a tranny? I've rebuilt a lot including 911 Porsches. You guys seem to think a cap is going to have water pouring into the case. Not true. The small amount of water that might get in evaporates from the heat of gear friction.

Think about the physics of it. Drill a .050" hole in the cap of a jar, put it on the jar and submerge it under water. What happens? Does water pour into the jar? No, the air pressure in the jar prevents it. Pour water out of a gas can with no vent, what happens? It's hard to get out, same principle here.

Rob

 

[nmu98]

There's nothing wrong with tapping plastic. The plug itself is threaded and fits in the axle case. The plug in the cap has less chance of coming out than the dipstick itself.

Snow and rain aren't going to affect it one bit any more than they affect your tranny which is vented.
Did you ever rebuild a tranny? I've rebuilt a lot including 911 Porsches. You guys seem to think a cap is going to have water pouring into the case. Not true. The small amount of water that might get in evaporates from the heat of gear friction.

Think about the physics of it. Drill a .050" hole in the cap of a jar, put it on the jar and submerge it under water. What happens? Does water pour into the jar? No, the air pressure in the jar prevents it. Pour water out of a gas can with no vent, what happens? It's hard to get out, same principle here.

Rob

I understand what your saying, but do any automobiles (4x4) have a vent on top of the axle or do they have a vent tube that runs up to the body to help prevent contamination?

I have never rebuilt a porche tranny, but I have worked on more Jeeps and Full Sized trucks than most. There is nothing on those vehicles that would be set up like yours. I am not knocking you, I just don't feel that it would be a good thing.

I drive through to much stuff and I would be looking at that vent all the time worrying that it was going to get knocked off from a tree branch or rock. Thats me, I worry about that stuff.

I like the gear box dip sticks better. Like #1 from here. This ia all metal, no plastic and it has a cover to prevent, or help prevent contamination.

 

[Spudland_Dave]

I have never rebuilt a porche tranny, but I have worked on more Jeeps and Full Sized trucks than most. There is nothing on those vehicles that would be set up like yours. I am not knocking you, I just don't feel that it would be a good thing.

I've been thinking about the vent myself and the mental picture of my desired outcome was something similar to whats on the rear end of my GMC truck....small bung where the dipstick was with 18" of hose leading to a vent cap (on the frame rail of my truck)...on my 3520 I was gonna install that vent cap & hose somewhere nice & neat.
The only reason it hasnt been done yet is I wanted to retain some sort of dipstick functionality...

 

[Rob-D]

I understand what your saying, but do any automobiles (4x4) have a vent on top of the axle or do they have a vent tube that runs up to the body to help prevent contamination?

I have never rebuilt a Porsche tranny, but I have worked on more Jeeps and Full Sized trucks than most. There is nothing on those vehicles that would be set up like yours. I am not knocking you, I just don't feel that it would be a good thing.

I drive through to much stuff and I would be looking at that vent all the time worrying that it was going to get knocked off from a tree branch or rock. Thats me, I worry about that stuff.

The reason I mentioned Porsche trannies is because they race in rain at high speed. No tube, no filter system just a small vent cap screwed into the box. Again, think about the physics of it.

Are you saying the trannies aren't vented?

Look at the profile, it's no more obtrusive than the plug itself. The valved on your tire has more chance of getting knocked off. Not only that, the dipstick isn't out in the open it's under the hood and you have to reach for it with about 3 inches of clearance. I built it low profile exactly to avoid problems, it extends about an 1/8 inch above the dipstick.

Rob