2007 John Deere Z425 zero turn - right side wheel not turning

And that last reply should have posted yesterday. I failed to hit Post Reply. Daggonit.

Update. So i tried again to bleed the air out. I opened the valve 2 full turns, started at low throttle, half throttle and full throttle, fowards and backwards. I didn't do it fifteen times each. I probably did it 5 times each. But it failed. I'm going to try it, again, a full fifteen times. Oh, I also closed the valve and repeated. I'm only using the affected side. I'm assuming since the arms are independent, and, the left side is working perfectly that I can ignore the left side. I'm going to try again. Appreciate all your suggestions!!!!

bryanfaz said:

And that last reply should have posted yesterday. I failed to hit Post Reply. Daggonit.

Update. So i tried again to bleed the air out. I opened the valve 2 full turns, started at low throttle, half throttle and full throttle, fowards and backwards. I didn't do it fifteen times each. I probably did it 5 times each. But it failed. I'm going to try it, again, a full fifteen times. Oh, I also closed the valve and repeated. I'm only using the affected side. I'm assuming since the arms are independent, and, the left side is working perfectly that I can ignore the left side. I'm going to try again. Appreciate all your suggestions!!!!

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If you have the TZT7 series transaxle ( should be a tag on each transaxle to identify model and serial number), watch this video.

Your operators manual.....

I think the rod you were originally adjusting is for creep while the control arms are centered so that he arms are even with each other and neither drive axle is providing any propulsion.

This is the image from your owners manual.....check out the note. No operation (wheels on ground) with bypass position.

Gosh, a plethora of information. First, the video showed the wheels not turning when the bypass valve is open. My wheels are turning even after I've turned the t-rod twice. I'm guessing I need to turn the t-rod more times?!?

I attempted to purge this afternoon for at least 45 minutes. No luck yet. However, if the wheels weren't supposed to be turning with the initial exercise (with the valve open), we may have found the culprit. I'm heading back out to my shop to work on it.

The manual you provided the link for (and thank you for doing that) is a more recent model than mine. My z425 is a 2007 model. But again, thanks!! I'm still going to read it.

OH, I almost forgot. I believe my hydraulic oil is low. The hydraulic oil reservoir has two lines and my oil is slightly below the add oil line or whatever it says. I'll grab some at the JD dealership tomorrow.

Thanks as always guys. The odyssey continues!!

bryanfaz said:

Gosh, a plethora of information. First, the video showed the wheels not turning when the bypass valve is open. My wheels are turning even after I've turned the t-rod twice. I'm guessing I need to turn the t-rod more times?!?

I attempted to purge this afternoon for at least 45 minutes. No luck yet. However, if the wheels weren't supposed to be turning with the initial exercise (with the valve open), we may have found the culprit. I'm heading back out to my shop to work on it.

The manual you provided the link for (and thank you for doing that) is a more recent model than mine. My z425 is a 2007 model. But again, thanks!! I'm still going to read it.

OH, I almost forgot. I believe my hydraulic oil is low. The hydraulic oil reservoir has two lines and my oil is slightly below the add oil line or whatever it says. I'll grab some at the JD dealership tomorrow.

Thanks as always guys. The odyssey continues!!

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Might want to check....most of these hydros use 30 wt motor oil, not "hydraulic" oil. Here is the link for anything past 2006 and yours still uses the Kanzaki DUP10 pump.


Now the pump, if defective, can be rebuilt and it's not all that hard. How easy?.....try this video.


I don't recall seeing any oil filters on any of these pumps in any of the images I've seen, just oil resevoirs. Can you confirm this? If so, that's a made to fail methodology. Additionally you may not need new parts if the internal plates are lightly scratched. But that's not saying they are.

Just found where your "T" handles are..bypass valves....looks like you can turn them out about 3 to 4 turns based on image of the bypass valves in this model. If it comes out no big deal, just a bit of oil lost just screw it back in quickly.


The DUP10 is most likely very close to the DUP10S....At the back of this manual is a troubleshooting guide. It also shows you the guts and all the torque values for assembly in a step-by-step......

RevB said:

Might want to check....most of these hydros use 30 wt motor oil, not "hydraulic" oil. Here is the link for anything past 2006 and yours still uses the Kanzaki DUP10 pump.

https://john-deere.manymanuals.com/gardening-equipment/z425/user-manual-11765/44

Now the pump, if defective, can be rebuilt and it's not all that hard. How easy?.....try this video.

I don't recall seeing any oil filters on any of these pumps in any of the images I've seen, just oil resevoirs. Can you confirm this? If so, that's a made to fail methodology. Additionally you may not need new parts if the internal plates are lightly scratched. But that's not saying they are.

Just found where your "T" handles are..bypass valves....looks like you can turn them out about 3 to 4 turns based on image of the bypass valves in this model. If it comes out no big deal, just a bit of oil lost just screw it back in quickly.

Client Challenge

The DUP10 is most likely very close to the DUP10S....At the back of this manual is a troubleshooting guide. It also shows you the guts and all the torque values for assembly in a step-by-step......

Click to expand...

I think, and I’m way out over my skis here, I read about an oil filter for the hydraulic pump. This pic is of an oil filter in the same location as whatever manual I read said it would be in. But, I am new to all of this. I’ve read and watched so much it all kinda runs together. Forgive me if I’ve misidentified something.

I’m also attaching pic of the oil reservoir for the hydraulic pump. That may not be the right piece of equipment.

And I would love for someone to tell me what the heck is in the third picture. I’ve seen ANY JD manual that has one on it and I’ve never seen it on another mower. Weird! I’m referring to the red t-knob. It has to be turned correctly or the mower won’t start.

Someone had asked me about a cable close to the t-rod. It is close but doesn’t contact.

bryanfaz said:

I think, and I’m way out over my skis here, I read about an oil filter for the hydraulic pump. This pic is of an oil filter in the same location as whatever manual I read said it would be in. But, I am new to all of this. I’ve read and watched so much it all kinda runs together. Forgive me if I’ve misidentified something.

I’m also attaching pic of the oil reservoir for the hydraulic pump. That may not be the right piece of equipment.

And I would love for someone to tell me what the heck is in the third picture. I’ve seen ANY JD manual that has one on it and I’ve never seen it on another mower. Weird! I’m referring to the red t-knob. It has to be turned correctly or the mower won’t start.

Someone had asked me about a cable close to the t-rod. It is close but doesn’t contact.

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Did you buy this new or from someone? That red knob looks like a battery disconnect....anti theft. The key doesn't pull out of the socket does it? If it doesn't start in one position but does in the other that's what it is.

bryanfaz said:

I think, and I’m way out over my skis here, I read about an oil filter for the hydraulic pump. This pic is of an oil filter in the same location as whatever manual I read said it would be in. But, I am new to all of this. I’ve read and watched so much it all kinda runs together. Forgive me if I’ve misidentified something.

I’m also attaching pic of the oil reservoir for the hydraulic pump. That may not be the right piece of equipment.

And I would love for someone to tell me what the heck is in the third picture. I’ve seen ANY JD manual that has one on it and I’ve never seen it on another mower. Weird! I’m referring to the red t-knob. It has to be turned correctly or the mower won’t start.

Someone had asked me about a cable close to the t-rod. It is close but doesn’t contact.

Click to expand...

And disregard on the 30 wt trans oil....manual says JD Hygard was used at the factory. My bad. And that is your trans filter. Might want to change that as well. The cheap thing to do is cut open the filter can and take the filter element out....just pleated paper....and spread it out and see if there are any metal bits in the pleats. Standard practice in the automotive and aircraft industry....not so much in the lawn equipment class tho.

bryanfaz said:

I think, and I’m way out over my skis here, I read about an oil filter for the hydraulic pump. This pic is of an oil filter in the same location as whatever manual I read said it would be in. But, I am new to all of this. I’ve read and watched so much it all kinda runs together. Forgive me if I’ve misidentified something.

I’m also attaching pic of the oil reservoir for the hydraulic pump. That may not be the right piece of equipment.

And I would love for someone to tell me what the heck is in the third picture. I’ve seen ANY JD manual that has one on it and I’ve never seen it on another mower. Weird! I’m referring to the red t-knob. It has to be turned correctly or the mower won’t start.

Someone had asked me about a cable close to the t-rod. It is close but doesn’t contact.

Click to expand...

More to think about......found this interesting. The higher viscosity TuffTech oil would mask some wear issues but it's still not certain that this isn't just an air purge problem......

And a better source for your operators manual.....

RevB said:

And a better source for your operators manual.....

OMM154566_D7

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Thanks RevB! Here are today’s updates. The JD dealer recommended 20W-50 oil. And I filled up to the top fill line. Went through the purge procedures for roughly 30 minutes. Both wheels will turn with the control arms with the bypass valve (T-rods) wide open. I would have thought just the opposite. I checked on something that surprised me. After all that, with the bypass valves completely shut, the right side wheel still turns freely. That should be evidence of the problem. Right?

bryanfaz said:

Thanks RevB! Here are today’s updates. The JD dealer recommended 20W-50 oil. And I filled up to the top fill line. Went through the purge procedures for roughly 30 minutes. Both wheels will turn with the control arms with the bypass valve (T-rods) wide open. I would have thought just the opposite. I checked on something that surprised me. After all that, with the bypass valves completely shut, the right side wheel still turns freely. That should be evidence of the problem. Right?

Click to expand...

This is one of those problems that invites a parts cannon approach. What are the fluid pressures being delivered to each drive motor? Are they different? Are the drive motors actually the problem or is it the pump? The DUP10 is just two pumps side by side in the same case delivering fluid under pressure to their respective wheel drive motors. The only way to definitively know is to be able to measure the flow rate and pressure of the fluid.

As for the bypass valve being open and the wheel motors moving the bypasses don't stop the fluid flow, it just short circuits the flow so it's not going to the wheel motors and goes around the pump section. There may be reresidual pressure that gets to the motors so that's not unsurprising.

In the owners manual I've not seen any procedure that calls for the bypasses to be open when exercising the levers fore and aft. An example for trans filter replacement...

"3. Clean area around hydraulic oil filter (B).

4. Place drain pan with at least a 9.9 L (10.5 qt) capacity under hydraulic oil filter, turn filter counterclockwise to remove and allow oil to drain completely.

5. Apply a film of clean oil on gasket of new filter.

6. Install filter. Turn filter clockwise until gasket makes contact with the mounting surface. Tighten 1/2 to 3/4 turn after gasket contact.

NOTE: Reservoir capacity is approximately 8.5 L (9 qt). Total system capacity with filter is approximately 9.9 L (10.5 qt).

7. Fill oil reservoir with approximately 8.5 L (9 qt) of oil.

8. Install reservoir cap.

9. Start engine.

10. Move throttle lever to the 3/4 fast idle position.

11. Unlock park brake.

12. Run engine in full forward position for five minutes and then cycle motion control levers forward and rearward several times. Check for leaks around filter.

13. Stop the engine. Check oil level in reservoir. Add oil as necessary."

That's it. No one is screwing with the bypasses to purge the system. Leave them closed except for when you want to hand move the machine. Try that.

If that isn't it you'd need to tee in a pressure guage on the right at the motor to verify a no pressure issue....