790 front axle leak

[scdawg]

I have a 2004 790 4wd with loader. 243hrs. I was bushogging yesterday and noticed gear oil leaking onto right front axle. Everything seems to be working fine otherwise. Could a seal be bad? I've read about gear problems but 4wd seams to be working fine. Any ideas? I'm almost afraid to ask.

 

[Tractor Pilot]

A picture would be helpful. Kind of a long shot, but any chance the leak is coming from the power steering cylinder and flowing down the shaft onto the right front axle?

 

[RoyJackson]

I have a 2004 790 4wd with loader. 243hrs. I was bushogging yesterday and noticed gear oil leaking onto right front axle. Everything seems to be working fine otherwise. Could a seal be bad? I've read about gear problems but 4wd seams to be working fine. Any ideas? I'm almost afraid to ask.

Probably a seal...that wouldn't disable the 4WD immediately, but would eventually (gears/bearing failures).
I suggest the first thing you should do is read your tractor manual about checking front axle lubricant (make sure you know how it's to be done) and going from there.

And, as Tractor Pilot wrote...try to determine where the oil came from...might not be the axle at all.

 

[scdawg]

I appreciate the replies.
I bought this tractor over the summer. I changed the front axle oil right after I bought it. The oil that is leaking smells like the same stuff.
I don't know all the terms for the parts but I'll try to describe where the fluid appears to be coming from.
The hub lugs go through the hub and screw into a green plate. Follow this plate toward the center of the tractor and you see a space where this plate joins the axle housing(?). This appears to be where the fluid is leaking from. The tractor is at my farm ~70 miles from here. I can get pictures next weekend if needed.
Thanks for the help.

 

[RoyJackson]

Go to the JD Parts website (you'll have to register) and take a look at the illustrated parts breakdowns. You may be able to identify the (possible) source of the leak.
It will help if you know the serial number of your 790...

Here's a link:
https://registration.deere.com/SignInServlet?EM_REG=Y&EM_FORGOT=Y&EM_USER=Y&TYPE=33554433&REALMOID=06-3bb086e1-cb58-002f-0000-5aaa00005aaa&GUID=&SMAUTHREASON=0&METHOD=GET&SMAGENTNAME=OpAnFthWQCMwxNqQtYaaC3w7zGStueQnd8qMH9pvQzDdnFHfyNMac8d4IYObwnEs&TARGET=$SM$HTTP%3a%2f%2fjdparts%2edeere%2ecom%2fservlet%2fcom%2edeere%2eu90%2ejdparts%2eview%2eservlets%2emaincontroller%2eSessionStartup%3fuserAction%3dfromEmail

 

[Tractor Pilot]

Here is a schematic of the front axle (4WD) for the JD790:

 

[Willl]

(you'll have to register)

What's with this register stuff ?

I use this part of JD and don't believe registration is required. Am I wrong ?, or is my browser auto signing in ?

Order Manuals and Parts Catalogs from JohnDeere

Here is a schematic of the front axle (4WD) for the JD790:

Seems to be missing a few pieces.

 

[RoyJackson]

Did you try the link?
It's for ordering parts...when you register, you select where you want the parts shipped.
BTW, the illustration below may be just one of 2 or 3 and not showing all the detail.

What's with this register stuff ?

I use this part of JD and don't believe registration is required. Am I wrong ?, or is my browser auto signing in ?

Order Manuals and Parts Catalogs from JohnDeere



Seems to be missing a few pieces.

 

[Hookblock]

If it's like a 4310 it's a simple fix.

http://www.tractorbynet.com/forums/john-deere-owning-operating/139924-4310-front-axle.html

I use the JD parts no log in required.

John Deere - Parts Catalog

 

[Willl]

Did you try the link?

Did you go any further than just where my link took ya ?

BTW, the illustration below may be just one of 2 or 3 and not showing all the detail.

BTW, the pic I posted was to supplement the pic posted above mine.

 

[beenthere]

I have a 2004 790 4wd with loader. 243hrs. I was bushogging yesterday and noticed gear oil leaking onto right front axle. Everything seems to be working fine otherwise. Could a seal be bad? I've read about gear problems but 4wd seams to be working fine. Any ideas? I'm almost afraid to ask.

Loosen the dip stick plug, as if it is tight, then the axle isn't vented. So when the oil gets warm, it squeezes past the seals. Works for my 4300. You may have just filled it to the brim too, and no room for expansion. There is a thread here somewhere that tells about a mod to vent the dip stick plug.
At least worth a try to see if the oil stops leaking after hard use.

 

[RoyJackson]

Loosen the dip stick plug, as if it is tight, then the axle isn't vented. So when the oil gets warm, it squeezes past the seals. Works for my 4300. You may have just filled it to the brim too, and no room for expansion. There is a thread here somewhere that tells about a mod to vent the dip stick plug.
At least worth a try to see if the oil stops leaking after hard use.

That venting was done by TBN member Arribil...it's at least 15 to 18 months since he posted that.
However, IIRC, the 790 axles are already vented...but I'm relying on my memory on that...

 

[scdawg]

Thanks for all the info. I'm not much of a mechanic but those diagrams do look familiar.
I know that when I remove the dipstick to check the oil level, it often sounds like air pressure is being released. I did just top off the oil before my last use.

 

[rsewill]

I bought a 4100 this spring. It leaked from the left front seal. After reading this forum extensively I decided the easiest, albeit not the best, solution was to drill a pin hole in the filler cap. I filled the pin hole with gun grease which pushed out within a few minutes (on a 40F day so the front differential certainly didn't get very warm.) Still easier to add a bit of gear lube than to replace another seal. I have a dab of grease mostly sitting over the pin hole.

 

[Willl]

However, IIRC, the 790 axles are already vented...but I'm relying on my memory

Nope. At least not from the factory.

 

[RoyJackson]

Nope. At least not from the factory.

As I wrote, I was dependng on my memory.
There is a hole in the upper side of the casting. It's even shown in the 790 manual (pics posted on TBN somewhere). A thread (has to be close to 2 years old (or more) speculated it was a vent since it seemed to have no other purpose.
This is what got Arribil motivated to vent the front axle of his 4200 (see one of my previous posts in this thread).
So, it might be a vent...might be just some result from the casting process. So, unless you know otherwise, you can't say it's not a vent...
My 790 has been gone for 18 months (along with the manuals).
Do you own a 790, Will? If you have one, take a look at the top of your front axle. IIRC, it's near the front differential.

 

[Tractor Pilot]

That venting was done by TBN member Arribil...it's at least 15 to 18 months since he posted that.
However, IIRC, the 790 axles are already vented...but I'm relying on my memory on that...

Here is the link to the thread Roy mentioned:
http://www.tractorbynet.com/forums/...ing/168295-does-everyone-have-front-axle.html

 

[Mighty Dodge]

My 4200 had a leak at the front axle. This was after I used the loader to lift the front of the tractor to fix a tire. There's a little end play in the spindle and I guess it disrupted the seal between the spindle and seal lip. Anyway after a week or so it stopped on it's own. Maybe you'll luck out and it'll stop. Has it been leaking long?

John

 

[scdawg]

It just started leaking this weekend. I noticed it on Friday after bushhogging a couple of hours. I'll run it for a while and keep my eye on the fluid level. Hopefully it will stop on its own.

 

[godaddy]

Mine developed a leak on the right side also. I noticed also that when I would check the front gear oil that it would have a little pressure in the front diff. after use(normal). Mine is a 2001 and has no vent. So, I drilled a small hole in the dip stick and placed some foam in it for a filter like. Mine does not leak anymore now. Not hard to replace one though. Did the left side acouple yrs ago.