John Deere 4120 front axle seal replacement

[Blueforester]

Couple of things here guys-

first off, shoot me your email, I have a PDF of the Tech manual you are welcome to for free

second, Deere just loves to put thin as water hydraulic oil in these front ends. They are nothing but big gear boxes, I worked in a dealer in the 90's and 2000's and when we had one like this we would, (with owners permission) put 145 wt gear oil in the front end. It is much thicker and would be a lot less prone to just pouring out like the water they use. You might still have a wet joint, but it just mighr be something you can live with for a lot less money. Just something to think about-
Good Luck

Joe

I want to say my manual called for J20D Hy-Guard and the dealer sold me the J20C saying that is all they use. Or vice-versa, I'll need to check. Not sure if this made a difference. I found this researching on-line where I guess in colder weather they were recommending removing the heavier weight oil and replacing w/ Hy-Guard in center section, but not the wheel hub. Not the same axle but I still thought it was interesting.

Mechanical Front Wheel Drive (MFWD) axle performance in cold weather

Blue

 

[Blueforester]

Sad to say... not looking good for my 4120.... JD was not helping to share repair specs. It is a two to four week wait to buy the service manual @$295.00... So I got the 4120 into the dealer. The seal was $44.00 and nut was $4.00 All total $389. Got the tractor home and put about 4 hours on her and daggon it the seall is already leaking again. So I call the dealer on Friday last week and they are so sorry... and tell me to bring it in right away and they will redo the seal. So I wait about 3.5 hrs and it all done. The guy takes the tractor for a spin around the lot 3-4 times, checks for leaks and we load er up and take it home. I bush hogged about 8 acres in two hours. Park it and bamm... it's leaking again.
Of course dealer is closed till monday. I will tell you, I saw another 4120 disassembled on Friday and the same service guy tells me JD stopped making the knuckle and its about $4K for a new one. As I am chatting with the guy he happens to tell me he saw a burr on my shaft and filed it down. Good grief... R you kidding me? I am betting the guy botched the job and knows it. I checked on line and a new shaft is over $500 but guess what .... not in stock. Apparently,these things are known for leaking seals and they do lots of them. BTW the second repair was no charge. Wish I had taken it to the dealer where I bought it... They warned me... If they can't resolve, I will do the work myself next time. It's just a seal for heavens sake. I will be calling JD corporate on Monday as well. Just ain't right that they won't keep shop manuals available and won't share torque specs over the phone...

Man I hate to hear that. My 4120 is about to turn 1,000 hours so I just went through it pretty good like flushing and replacing coolant and front axle lube etc. Then like I said then the hub started leaking. But I have to say it has been an awesome tractor and tight as a drum up till this point. Still have a few minor things to fix. One is water in one headlight. Looks like you can't replace just one you have to replace the entire headlight assembly.

Blue

 

[Tundradog]

Update of the axle seal SAGA.....
Selling dealer took the tractor in on Tuesday. Service Tech really knew his stuff and made no promises. They called me late in the afternoon with diagnosis. Straight up the hub housing had been noticably ground down inside the seal seat. Apparently not a neat job. No doubt the work of the previous service tech. Micrometer measurements indicated far too much material removed and out of round..... No way the seal would ever seat properly. Good news is the axle stub shows no sign of damage and is mic'd in tolerance. So we wait for housing to ship in. Axle gets new bearing set just to be safe and is ready to go. Looks like about $1k for correct repair. Lesson learned.....

 

[2001 JD4110]

I just got into this today with my 2001 4110 which prolly is the same deal. Check out my post here...http://www.tractorbynet.com/forums/parts-repairs/338024-jd-4110-front-axle-seals.html#post4147738

 

[arlen4720]

Update of the axle seal SAGA.....
Selling dealer took the tractor in on Tuesday. Service Tech really knew his stuff and made no promises. They called me late in the afternoon with diagnosis. Straight up the hub housing had been noticably ground down inside the seal seat. Apparently not a neat job. No doubt the work of the previous service tech. Micrometer measurements indicated far too much material removed and out of round..... No way the seal would ever seat properly. Good news is the axle stub shows no sign of damage and is mic'd in tolerance. So we wait for housing to ship in. Axle gets new bearing set just to be safe and is ready to go. Looks like about $1k for correct repair. Lesson learned.....

That sucks. No way they should have ground on that part. I use a jewelers file and emery paper. Allot harder to get into trouble that way.

But, on the flip side, it's hard to know how much damage there was to begin with. But the mechanic should have called you and discussed replacing the part or trying an act of desperation to save it.

 

[2001 JD4110]

Are you sure its not just the wear sleeve the seal rides on?

 

[Tundradog]

Are you sure its not just the wear sleeve the seal rides on?

So here is the rest of the story..... Selling dealer, felt best to replace both housing, and axle assembly including seal and bearings. Three key elements found.
1) housing was so enlarged that pressing in seal was not going to work. Seal fit so loose it literally just dropped into the housing and fit flush. There is supposed to be a detent in the housing but so much material removed you could hardly tell it was there.
2) Technician doing disassembly noted no permatex on the seal which is required by technical manual instructions for reassembly. In other words botched job by the other JD dealer.
3) Seal was damaged... like the inner rubber seal that meets the axle shaft was torn.
4) Check of the wheel before removal indicated there was excessive lateral movement on the tractor. Once they removed the housing they determined the assembly could not have possibly been put under 1200 lb axial load when torquing the new retention nut. Bearings were suspect due to having been run on for a couple of hours while loose.

I have all the old parts for inspection and can say the axle probably ok as are the bearings. Housing is ruined.
Yes, I had the whole thing replaced for peace of mind and $1600.
Lesson learned... don't run your tire flat and bust the bead.... It will cost you dearly.

 

[2001 JD4110]

Yea that sux but now you're on the other side of the repair. I know, most JD parts are sooo expensive! It's downright scary & it shouldn't be that way. I gotta still figure & execute a plan on my tie rod & p/s ram joints for my new tires. Your story makes me think of 1 of my hip replacements yrs.ago, he supposedly was very good yet overbored the femur & had to get parts 60 miles away & spent 12 hrs doing a 3-4 hr.job subsequentially requiring more difficult work in the future I guess luckily for me I have a A+ tech at our local dealer who "at least this time" didnt mind sharing his knowledge.

 

[WSC73]

Couple of things here guys-

first off, shoot me your email, I have a PDF of the Tech manual you are welcome to for free

second, Deere just loves to put thin as water hydraulic oil in these front ends. They are nothing but big gear boxes, I worked in a dealer in the 90's and 2000's and when we had one like this we would, (with owners permission) put 145 wt gear oil in the front end. It is much thicker and would be a lot less prone to just pouring out like the water they use. You might still have a wet joint, but it just mighr be something you can live with for a lot less money. Just something to think about-
Good Luck

Joe

Is the tech manual still available?