John Deere D125 won't move forwards or in reverse, moves by hand whether bypass rod pushed in or out

[Sounder]

Update: the issue was a missing axle key. The mower now moves under power. Thanks for your help!

I recently bought a property and the previous owner left their John Deere D125 there (the rear axle was up on blocks, so I assume the mower was broken and he couldn't fix it so just left it there for me to deal with, or he was just working on that flat tire not sure) which I'm trying to get running.

I put in a new battery and the engine starts up fine and sounds good, but the mower will not move forwards or in reverse. The drive belt seems to be running fine once the parking brake is disengaged, and the axle is not spinning, it just seems the transmission is not being engaged. I can push the mower by hand whether the bypass rod is pushed in or pulled out, so I'm wondering if the transmission is disengaged and pushing in the bypass rod is not engaging the transmission like it should. The bypass rod is connected to the arm properly it seems like (the arm moves when I push the bypass rod or pull it out). Would this point to an internal issue in the transmission?

Let me know if I need to provide any more info. Thanks in advance for any help.

 

[StarTech]

Check for missing axle key.

 

[Sounder]

Check for missing axle key.

Thanks I'll do that when I'm back on the property this weekend. If the axle key was missing would it mean the axle just spins without the wheels moving? It didn't look like the axle was spinning at all but I'll give that a closer look next time to make sure.

Would that cause the mower to be able to be pushed even with the bypass rod pushed in?

 

[bertsmobile1]

Take some contortionist pills then put a pair of vice grips / water pump wrench etc on the input shaft and with your other hand on the pulley rotate it .
The pulley is on a fine spline and has been known to strip
Other than that there could be no oil or the motor pump unit could be toast
In that unit they are only good for about 1000 hours tops .
Probably best to pull it out and do some checking

 

[cds13ca]

These tractors have a hydrostatic transmission, it requires the oil to be changed!! The oil can burn out over the years and not hold any pressure to move the wheels. The manual says the transmission is sealed and it says it can't be changed. They want you to spend $1000 on a new transmission. I've done it several times with success. Remove the transmission completely. There's a pressed in cap that can be removed carefully with 2 - thin flat-head screwdriver. Look it up on youtube, the process isn't that hard if you are willing to tinker around a bit.

 

[grumpyunk]

If the wheels are keyed to the axles as designed, you should not be able to move the mower with the bypass pull rod released. If the bypass lever spring has failed or fallen off, then the lever may be allowing bypass internally. Bypass is allowing the path between the pump and the motor to bleed fluid instead of making it do work.
If the bypass lever is seated properly by the spring, then if it can be moved the pump or motor are likely so leaky the fluid when pumped builds no pressure. It should seal and form a low-leakage supply and return from pump to motor and back internally. If the pump or motor leak too much, there will be no pressure and no hydraulic lock to prevent motion.
Leaning on a hydrostatic driven mower with the release in normal position should give an indication of the internal leakage condition. One in good condition will be almost impossible to move when in any gear, or neutral.
tom

 

[sherri]

I recently bought a property and the previous owner left their John Deere D125 there (the rear axle was up on blocks, so I assume the mower was broken and he couldn't fix it so just left it there for me to deal with, or he was just working on that flat tire not sure) which I'm trying to get running.

I put in a new battery and the engine starts up fine and sounds good, but the mower will not move forwards or in reverse. The drive belt seems to be running fine once the parking brake is disengaged, and the axle is not spinning, it just seems the transmission is not being engaged. I can push the mower by hand whether the bypass rod is pushed in or pulled out, so I'm wondering if the transmission is disengaged and pushing in the bypass rod is not engaging the transmission like it should. The bypass rod is connected to the arm properly it seems like (the arm moves when I push the bypass rod or pull it out). Would this point to an internal issue in the transmission?

Let me know if I need to provide any more info. Thanks in advance for any help.

I've seen videos where someone takes off the back tire and the keyway piece drops out of the axle and gets lost. According to the video that little part lets the wheels move. Look up on "you tube" for back tire keyway on riding mowers.

 

[bertsmobile1]

I've seen videos where someone takes off the back tire and the keyway piece drops out of the axle and gets lost. According to the video that little part lets the wheels move. Look up on "you tube" for back tire keyway on riding mowers.

Yes the keys do drop out and get lost
However Sounder specifically said the AXEL is not moving .
So keys or no keys are a moot point
If the axel is not rotating then the wheels will not rotate
So Sounder either has a stripped input pulley , totally trashed pump/motor unit or broken diff
Internally there are a couple of shafts that are splined on that can also strip .

 

[Its Me]

I just fixed one that had the same symptoms, found that the Idler pullies and the drive belt to the transmission were the problem, the plastic pullies were melted, he went to John Deere they wanted 2,100.00 to fix it, I charged him 800.00 but changed those items, changed the bearings on both spindles and a Idler pulley and gave it a bath, he was impressed, check the transmission belt Idlers first, good Luck, Joe`

 

[sherri]

I just fixed one that had the same symptoms, found that the Idler pullies and the drive belt to the transmission were the problem, the plastic pullies were melted, he went to John Deere they wanted 2,100.00 to fix it, I charged him 800.00 but changed those items, changed the bearings on both spindles and a Idler pulley and gave it a bath, he was impressed, check the transmission belt Idlers first, good Luck, Joe`

What preventive maintenance would you suggest to avoid the problems with the plastic pullies and drive belt? What causes those problems?