JD 4600 4WD Leaking Front Axle

[DanMc77]

I checked the axle on the 4600, lifting the wheels using the loader. Everything is very nice and tight, and it seems to have leaked less over the past few weeks. But less leaking could be due to thicker lube in the cold January temperatures of winter. I have attached a couple photos of the right side that show the lube leaking from the steering pivot. I tried taking out the drain plugs to put in 85w-140 lube, but the plugs are all stuck. The ones down at the bottom of each hub are a bit knarled up from scraping up on rocks or other obstacles and won't even take an allen wrench. The one in the center is so tight, I'm afraid of snapping off the allen wrench or stripping out the hex portion of the plug. I wasn't prepared to start drilling out plugs in the middle of winter.

Maybe somebody here knows of some trick for extricating these drain plugs. I think one suggestion may be to TIG weld bolts onto the lower plugs, I don't have a TIG welder or the welding skills to do this safely. Drilling and using a screw extractor may be my only option for the smaller knarled up plugs.

Anyway, I'm beginning to consider whether the lack of a vent in this axle is leading to sucking in air through the seals when it's cold, then expelling oil when the temperature warms and pressure builds. Perhaps modifying the yellow axle fill cap to add a small breather vent hole and incorporate some kind of filter would be a helpful improvement.

 

[pmsmechanic]

I've considered installing a vent also. I don't like the idea of a vent on the yellow fill plug because I've been in water deeper than the fill plug. Not often but it has happened. I haven't spent a lot of time on the idea but my thoughts were to remove one of the top bolts on the differential housing and drill it out for a vent. If I could then attach a vent hose to the bolt and lead it up into the engine compartment I would have the vent issue solved. If I ever need to rebuild the front axle there will be a hole drilled for a vent.

Your axle has a lot less oil on it than mine did. The ground had a small puddle every time and the tire/rim was all oily.

I've had problems with those small drain plugs too. I even had one fall out once. I don't like to use regular allan wrenches on them. I have a 3/8 drive set of allan wrenches and it feels like it's easier to get them out without issues when I use those. Take a spare allan wrench the correct size and cut it off about a 1.5" long. Taper the one end slightly and carefully tap it into the drain plug. That will straighten the holes out well enough for you to insert a proper allan wrench. If you tap on the short stubby than you just made with a small hammer while it's in the drain plug it will loosen the drain plug to the point where you can remove it. The key is moderate taps with the hammer. You don't want to push the stubby allan wrench right through the plug. If you tap say 20 times on each plug daily for a week they'll come out easily. It doesn't hurt to apply something like WD-40 either.

 

[DanMc77]

PMS: Thanks for the input. I'll have to start tapping once we have some warmer weather. Maybe warmer temperature will cause things to expand a bit and it will loosen up a bit.

I topped off the axle with a lube that is Hyguard-compliant and left the yellow cap a little bit loose. We will see if it still leaks. If it still leaks, then when I can get the plugs out and drain it, I'll put in the heavier 85w-140 gear lube.

A fun machining project may be to make an aluminum fill plug with a nipple on the side for a little vent tube. As for me, I'll keep my front axle out of water. Bearings don't like water. I had a Toyota Camry sitting in a parking lot that flooded up over the rocker panels and got totalled. I collected the insurance, then bought it back cheap, pulled out the seats, lifted up the carpet enough to get air under there and dried out the interior with a pile of fans in about 24 hours. It was too old to get a salvage title, so I was good with that. Anyway, a year later both front wheel bearings were shot, and I blame the water for that since both failed at the same time.

 

[TnAndy]

Similar repair on my Yanmar year or so back. Bearing went, causing seal to eat itself, causing a puddle of fluid on the floor.

Fairly easy fix, once I got the parts rounded up.

 

[pmsmechanic]

My bearing set up is very similar to TmAndy's Yanmar in the above post. According to the parts diagrams the 4600 has tapered bearing vs ball bearings.

Water getting into tractor front wheel assist bearings won't have the effect that that it will on bearings on a front wheel drive car. The way the tractor front end is designed any water goes through the bearing and collects in the bottom of the housing. If you drain the housing shortly after being in the water there won't be any issues. On a front wheel drive car the ball bearings are lubricated with grease rather than oil. Any water entering mixes with the grease and eventually destroys the bearing.

 

[DanMc77]

Andy, Thanks for sharing these photos!

For sure, the 4600 has tapered roller bearings on the front wheel axles. The re-assembly of these axles is very interesting:

- Apply 1200 lbs axial load on the web of the bevel gear 41T, while rolling and oscillating the bearings to ensure proper seating of the bearing.
-With the load applied, measure the dimension between the gear face and the end of the hub shaft (non threaded portion).
-Select the same thickness shim(s) as the measured dimension, and install the shim(s) to the shaft.

What in the world is this talking about? It sounds like they're basically preloading the bearings to 1200 lbs. This looks like something I would take to a good machine shop to have done. I bet that the dealer would be sending this off to a machine shop too. So the shaft is set down on the output flange, and then the load is applied to the gear. Then the final drive cover can be rotated under load to seat the bearings and this measurement is taken. Nominal 345 ft lbs of torque for the nut. That's some serious torque.

Comments anybody?

 

[TnAndy]

Wow......glad yet AGAIN I bought a Yanmar ! (Not that the stupid bearing failed.....ahahhahaa.....but that repair was simple)

How the heck does on 'apply a 1200lb axial load' on that ?

 

[DanMc77]

I'm guessing that the added complexity is because the 4600 is a larger 43 hp machine. Yeah, how does this 1200 lb load get applied, and who has a scale that can measure that kind of pressure? Pressure could me calculated by checking hydraulic pressure and knowing the piston size of the hydraulic cylinder?

And, oh by the way, I think that just about any smaller JD tractor is made by Yanmar. The 4600 is still called a "Compact" tractor and has a Yanmar engine, so I'm betting that the rest of the core machine is also Yanmar.

 

[CADplans]

And, oh by the way, I think that just about any smaller JD tractor is made by Yanmar. The 4600 is still called a "Compact" tractor and has a Yanmar engine, so I'm betting that the rest of the core machine is also Yanmar.

IIRC,, My axle is not Yanmar,, or JD,, is it something like DANA or some other axle manufacturer,,,

 

[pmsmechanic]

IIRC,, My axle is not Yanmar,, or JD,, is it something like DANA or some other axle manufacturer,,,

My front end has Spicer cast into the housing.

And I've been thinking about the bearing preload. You don't have to do it the way that John Deere says. You just need to have 1.4-4.1 Nm's of rolling torque once it's assembled. You aren't changing the bearings or anything other than the seal. Measure the rolling torque before disassembly, replace the seal and measure the rolling torque again. It'll be higher because of the new seal but if it's within specs your good to go. I would reassemble with the old nut first. Measure and if all is good then use the new nut as per assembly manual.