'93 Deere 310D front differential locked and cant unlock

[hellspcangel911]

Hi all,
Ive owned this backhoe loader for a few years, its been a great work horse around the farm. I was out clearing some land, it was wet, muddy and cold out, and I engaged MFWD to help climb out of the mud. I turned it off, the indicator on the light went off, but I still had a very difficult time turning. I had the same thing happen once before when spreading millings on the road, it was a dry day but also just below freezing temps. That time I was able to get the front unlocked by shifting back into MFWD, and out. Not so lucky this time around.
I think when MFWD is engaged the front differential is locked and the issue I am having is that even after the MFWD is disengaged the diff is still locked.
I believe the lock is achieved hydraulically? Where should I start looking to fix or at least disable it?

thanks,
george

 

[Delmer]

Yep, jdparts shows it as plates and disks that should be operated hydraulically, but I couldn't find the valve that controls the front diff lock. The rear diff lock is a mechanical linkage, right? On a JD with a hydraulic rear diff lock, the valve is a foot operated pressure reducing valve. They can get stuff stuck under the ball, so they don't release. If you can find the valve that controls this front diff then that is the obvious place to start. If you want to disable it only, cap the hoses if they're external. That could also be the next step in diagnosing.

 

[hellspcangel911]

Hey Delmer,
Thanks for the response. Your absolutely right the rear diff lock is mechanical, pedal on the floor. Its a bit of a bear and has to be pulled up manually to disengage. I see the two hydraulic lines going to the front diff, I'll trace them back and see where it takes me.
Am I correct in assuming the Hydraulic pressure locks the diff? I know with the MWFD engagement, if the solenoid is unenergized, the default is 4x4.

 

[Delmer]

Yes, the front diff lock looks like wet brake/clutch plates, that would be operated with hydraulic pressure, just like any other JD hyd diff lock.

The two lines will be the pressure line (at several hundred psi when locked) and the leakage return so that the leakage doesn't fill that axle with hydraulic fluid. probably

It's also possible that there's an internal failure that's locking it up, either in the diff itself, or one of the plates warped or came apart and locked up the diff lock. If it's locked up with no hydraulic pressure, then it's obviously not the hydraulic valve.

 

[kenferguson]

i am having same problem actually it is the reson i joined this site i thought it might be the switch but that check ok im thinking it the solenoid but trying to figur out which of the three on the left side of tran. but as a temp fix to keep the hands from tearing up the front knuckels i pulled the front drive shaft

 

[hellspcangel911]

i am having same problem actually it is the reson i joined this site i thought it might be the switch but that check ok im thinking it the solenoid but trying to figur out which of the three on the left side of tran. but as a temp fix to keep the hands from tearing up the front knuckels i pulled the front drive shaft

What machine are you running? On mine when I switch off the MFWD, it would take a bit of time for the light to turn off, usually engaging Forward, then stop, then engage Reverse was the fastest. Now Im still able to get the indicator light to turn off, which is activated by a ball switch on the transfer case and not just a dummy switch off the actuator. So in my case I think the issue is the front diff is locked while yours sounds like the MFWD is engaged.
With the weather and work I haven't been around to further troubleshoot, I'm hoping it's just a solenoid/valve but fear it's damage in the front axle. Ifi disconnect the front hydraulic lines and it's still engaged, is it worth changing the front axle fluid? Or at least draining it first to see what comes out? My issue seems more prevalent in below freezing temps.

 

[hellspcangel911]

I went to go troubleshoot it, but the front diff was unlocked despite being locked when I parked it last time. I needed the machine to finish spreading some woocdchips and didnt get around to troubleshooting. Im planning on changing the front diff fluid, I believe its just standard SAE90?

 

[JonathanMA]

The front axle is limited slip only --there's no hydraulic lock function in there. With MFWD on or off, the tractor should still turn left/right-- With it on, there may be some ratcheting noise heard when the limited slip is slipping during a turn, but it should still turn. Either there's a problem in the front differential thats physically locking it (drain oil and look for debris) or the rear diff lock is on. When the rear diff lock is engaged, the tractor just wants to go straight.

 

[hellspcangel911]

Hey Jonathan, thats for the clarification. Ive never heard a ratcheting noise and its always been a bear to steer with MFWD engaged. Lately Ive been operating in tighter spaces so its been much more noticeable I guess. Ill drain the front diff fluid and see what comes out. Any point in checking the front hubs as well? Dont want to go thru the effort if its not necessary and I'll end up doing it again if I need to rebuild the front axle.

 

[JonathanMA]

Won't hurt to check them -- although getting the fill/check plugs out is sometimes a project in itself.

 

[kevin37b]

If you do not want to go through the effort to check it out , just buy a new hoe !

 

[hellspcangel911]

Cleaned out the crud from the plug head but it looks like the previous owner rounded it out on the drain. Is it supposed to accept a 3/4 square head? What size hex does the fill take?
Thanks

P.s. I will not be buying a new hoe, when this one just needs some wrench time.

 

[Howey75]

Should be 1/2 in. square drive iirc.Ive had to use a chisel to get them to turn already although it can mess the plug up pretty bad.Worse case scenario is get a newplug from Jd.Definately check the hubs to make sure they have oil in them.Ive seen the seals leak pretty bad also.Agree that it should still turn ok even with the mfwd engaged.Keep us posted

 

[hellspcangel911]

If it's a 1/2" square then it's already rounded and rusted out. I ordered the orings and a new drain plug.
The drain on the hubs is better but I'll do those after I drain the axle.
Any suggestions on removing the old plug? Just clean it up, quickly weld in a 1/2" bolt and hit it with the impact gun?

 

[Delmer]

If you can weld something in, that should work. The welding will cause expansion and contraction that usually loosens stuff up good. I'd use a nut instead of a bolt typically, and use a breaker bar with cheater instead of impact, figuring it's easier on the weld. For overhead I can see the advantage of a bolt instead of dropping a big glob of weld trying to fill too big a hole.

Does it look like a hex drive maybe? you could try sharpening the slots with a chisel to get a hex to fit, even sharpen the hex and drive that sucker in.

 

[hellspcangel911]

the fill plug at the top is a hex, the drain is a 1/2" drive. I ordered the new one with o-rings. I found a hardened bolt, Ill grind down the sides to fit it into the old rounded plug then weld it up.

 

[hellspcangel911]

Well I got the old plug out, and the fluid that came out was completely clear, looked brand new. The magnetic back of the old plug had a thin film on it, but not enough to quantify.
Installed new orungs, drain plug, filled to capacity (1.7gal). The fill plug uses a 3/4" hex.
What's the next step?

 

[hellspcangel911]

One observation, while the old diff fluid was entirely clear, it had the same viscosity as hydraulic fluid- very runny. By comparison the new 85-140 fluid was super thick.
Since I had everything out, I did the hubs as well. One came out fine, the other was so rusted the head stripped and I had to weld a bolt on there. The fluid in the hubs was pretty clean but not clear like the diff.
Ill try it out tomorrow and see if I'm still getting the lockup.

 

[Deon]

hellspcangel911,
Can you tell me how you were able to remove the 2 plugs? Mine also stuck in there.

 

[hellspcangel911]

It actually went easier than expected. Make sure you buy new plugs and o-rings. The orings from Deere are surprisingly thin and I couldn't get then to match up with any in the assortment packs.
I ground the rust off the face of the old plugs, took half inch thick grade 5 bolt and inserted it into the rounded out plug I then welded it to the face and while still hot gave it a few short huts with the impact. It losed right up. It's easiest to have the bucket down and the axle up so you can teeter it to drain without having all the fluid rush out when you remove the plug. Also, I always disconnect the alternator and batteries when welding on the Deere.
That being said, now I can't get MWFD to engage. The indicator light won't even come on. Need to do some more troubleshooting.