Hydrostatic Issue - Dealer says replace - About $8000

Wes Crawford · Aug 29, 2017

Background: 2004 JD 4410 Hydro, 1100 hours.

A few weeks ago I used my tractor with no issues. Worked fine. The next time I started the tractor, I got some serious movement hesitation with the hydro. Push the forward pedal and the tractor would jerk forward a few feet, hesitate for several seconds, then jerk forward again a few feet. No continuous movement forward. It was the same in reverse. I let it warm up for 20 - 30 minutes and then it worked much better with an occasional hesitation that went away when I started brush hogging a 2 acre field. The tractor ran fine the rest of the day and until I put it away. By the way, the loader worked as well as always and the PTO obviously worked. Last week I got started the tractor and the hesitation and jerky movement was back. This time I let it warm up and it got better, but still some occasional hesitation. I then went into the woods and brush hogged my logging roads and trails. It wasn't perfect, but it more or less worked. I thought it might need a clean filter, screen, and oil, so I changed the filter, oil, and cleaned the screen the next day. When I started it up the next time, the hesitation and jerky movement was even worse. The tractor would hardly move 10 feet in a minute.

So, I called the dealer yesterday and had them pick it up. They analyzed it per JD requirements and found that the internal pressure was only about 1000 whereas they said it should be about 5400. JD's recommended solution is to replace the hydro completely. They said they didn't have the capability to repair the pump assembly. So, they said the cost of a new hydro is $4350. Labor to replace would be about $3000 and miscellaneous seals, fluid, etc might be another $1000.

A new dealer bought out the one I originally purchased the tractor from in 2004. The techs are competent I imagine, however, I'd feel better about the diagnosis if an older guy who worked on the tractor before was still there. Can't hydro's be repaired instead of replacing the entire housing, gears, pump, etc? Does anyone have any words of wisdom or suggestions for me? Thanks!

Deere Dude · Aug 29, 2017

After changing my trans oil I can count on sluggish and erratic movement for a few weeks. Maybe to work all the air out, I don't know.

Later I found it was now working adequately after I changed the oil so I asked around on this forum as to suggestion. I knew the oil level was full, but then I rechecked it and found it was 1/2" below full. So I got a quart of Lo Vis Hygard and dumped it it. To my surprise it actually took a whole gallon from that point on the dipstick.

I would verify the level every day before using it and make sure it is the right oil. An $8000 pump wold make me squeamish and would check any alternative before that happens.

kennyd · Aug 30, 2017

I think I'd try the engine speed sensor, they are about $70 and can cause issues with the eHydro operation if the signal is not clean.

texasranger556 · Aug 30, 2017

I don't know how the "E" stuff plays into it but to me it sounds like low charge pressure. My 4400 was acting similar when I bought it although not nearly as bad as you described. We lapped the valve plates in the transmission, put it all back together and it did the exact same thing (the plates weren't very bad at all, 500 hours of use). The power steering pump is also used to charge the transmission, there is a regulator valve that holds 150 psi or so into the transmission. It is up next to the hydro filter on the front of the transmission. When we removed it the spring was sort of jammed. Took the spring and poppet type thing out, put it back in and it's been good ever since. In retrospect we could have saved a whole day of work, but in the end the transmission is like new now.

Ask them what the charge pressure was when they measured it. If you don't have good charge pressure, I don't believe you can trust the high pressure readings.

Tx Jim · Aug 30, 2017

5400 psi factory setting for hyd pressure sounds very high to me.

texasranger556 · Aug 30, 2017

6000 is what mine calls for, 200 for charge pressure. Here is the thread I started a couple years ago.

http://www.tractorbynet.com/forums/showthread.php?t=344133

texasranger556 · Aug 30, 2017

Regarding your question about repair, a lot of dealers won't do it because it's a lot of labor splitting the tractor and getting the hydro out. If they screw up or mis-diagnose then they end up eating the cost of doing it again, so they just quote a new transmission to be safe. Another dealer or independent shop may be willing to fix rather than replace.

When I was looking at repairing mine, the parts diagrams showed you can order individual components from Deere. I've seen HST parts available from Kubota too. On the ones I've seen, it's usually the valve plates that show the most wear due to cavitation, contamination, oil overheat/breakdown. Sometimes just wear. This lets oil leak between the ports instead of driving the motor. You can lap the plates back smooth and the only cost is labor. Or buy new plates if available. However this type of failure is normally gradual degradation, not immediate like you describe.

The pistons/slippers can also go bad which usually means buying the whole rotating assembly because the pistons I'm told are precision ground to fit the cylinder block so they sell as a set which is obviously more money.

In your case if the charge pressure checks out ok, then due to the rapid onset of issues I'd lean more toward a slipper failure. Once one fails it can score up the swash plate face and damage the rest of them pretty quick. If you run long enough the metallic particles can ruin the motor too.

I don't have any experience with the e-hydros as far as a control/sensor problem that could explain the behavior you experienced.

Dfkrug is also experienced with hydro transmissions, so he may add comment/corrections to what I've said. If you do end up needing a new transmission I would be interested in doing a teardown on the old one and post the details here. I periodically visit in-laws near Indianapolis.

dfkrug · Aug 30, 2017

texasranger556 said:
Dfkrug is also experienced with hydro transmissions, so he may add comment/corrections to what I've said. If you do
end up needing a new transmission I would be interested in doing a teardown on the old one and post the details
here. I periodically visit in-laws near Indianapolis.

All good suggestions.

A proper diagnosis at the dealer is to check fwd and rev relief pressure, AFTER verifying the charge pressure.

I do not know the e-Hydros either, but Deere HST parts are available so buying the whole thing is not
necessary.

I do hope that this unit gets properly diagnosed and a post-mortem performed and posted on TBN. I would do
it too, TEXAS.

Let's hope it is an e-Hydro component, or a bad flow divider on the PS pump.

Wes Crawford · Sep 8, 2017

Everyone, Thanks for the comments and analysis. I appreciate it. I'm having the dealer return my tractor to my tree farm. I called another dealer and explained the problem and the pressures to them and they weren't certain that a new transmission was needed. They have a technician who has 40+ years of experience and they are going to consult with him when he returns from vacation next week. I believe I'll have them pick it up so they can do a thorough diagnosis of the problem. They are farther from my farm, so I'll have to pay a $50 RT delivery and return, but that will be worth it. I'll see what result I get next week and then post what I find. I appreciate the offer to look at it when you are in Indiana, texasranger556.

RoyJackson · Sep 10, 2017

Please do keep us up to date on what the tech determines!

pmsmechanic · Sep 10, 2017

Subscribed.

stingray1 · Oct 30, 2017

Any updates?

BleedingOrange · Oct 30, 2017

A second opinion is NEVER a bad thing. Glad to read that you are getting one.
I would be asking for the diagnosis and solution to be put in writing, including estimated costs of all material and labor.
Scammers are less likely to want to document stuff, especially IF they are trying to rip you off.
Hopefully tractor repair shops are not becoming as bad as vehicle repair shops, with false claims and repairs.
Like someone else mentioned earlier, please keep us informed on what the real fix is, and cost, versus your first guesstimate.

mike48130 · Dec 5, 2017

Like said above, you need to check the charge pressure first, but that is tied to the power steering, so if the steering is good, you probably have enough pressure. There is a pressure relief valve that controls the hydrostatic trans pressure, you need to add shims to it to adjust. There is a seat there that might be damaged. Located under the center of the tractor next to the test ports. The hydrostatic trans is a pump and motor just bolted together. It is probably rebuildable, but not thru JD. My 4210 has a Sauer Danfoss tag on the trans I noticed when I was under there.

I just rebuilt a pump on a Bobcat, and when it was bad there was a chopping feeling when driving and loss of power on one side. These are usually variable piston pumps with piston or gear pumps. When a piston goes bad, it becomes a leak thru, but only when that piston is moving or should be moving fluid. It does not go away, if it is bad, it is bad.

The E part of all this is just a 12VDC coil that moves a magnetic hydraulic valve spool. Current controls the amount of movement of the spool. The spool sends the hydraulic fluid to a cylinder that moves the angle of the swash plate on the piston pump that controls the volume and thus speed. There is a test in the service manual for these I think.

When I first got my 4410, I noticed it was considerably slower than my neighbors 4410, so that is why I know most of this from testing mine. My pressure was low, and I adjusted the pressure to be right.

There is an order in which you need to check the pressures and such, and a good mechanic will do that so they know the whole story.

1100 hrs seems low for a trans to go out. I have 1100 on my 4410 and it is very strong.

I hope it is not bad, that is a big bill.

texasranger556 · Dec 6, 2017

mike48130 said:
Like said above, you need to check the charge pressure first, but that is tied to the power steering, so if the steering is good, you probably have enough pressure.

In my case the steering worked fine but charge pressure was low which caused the transmission to chatter at low engine RPMs. It ended up the charge relief valve that had jammed open. Removed it and re-assembled, fixed the issue.

The steering relief valve opens at 1500 psi then dumps to the charge circuit which reliefs at 100-150 psi.

I agree with the rest of your post.

dfkrug · Dec 6, 2017

texasranger556 said:
It ended up the charge relief valve that had jammed open. Removed
it and re-assembled, fixed the issue.

Did you have to buy a new charge RV? Is the charge RV adjustable, or fixed (welded) to keep you
from adjusting it? How did it fail?

texasranger556 · Dec 6, 2017

dfkrug said:
Did you have to buy a new charge RV? Is the charge RV adjustable, or fixed (welded) to keep you
from adjusting it? How did it fail?

From my understanding it's just a plug holding a spring into a round piece of steel that presses into the orifice to maintain charge pressure. It was my dad who actually took it out and he said the spring felt like it was jammed off center somehow. No clue how it got like that, but simply re-installing was enough to fix the issue, that was about 100 hours ago and still runs great.

You can add shims.

mike48130 · Dec 6, 2017

Here is the picture from the service manual.

It should be part number LVA12615 on the parts diagram I think. You need to order the shim kit which I don't see.

Part Number: LVA12615
Remarks: CHARGE RELIEF VALVE, (SUB FOR LVA11862) (ALSO ORDER LVU14595)

Daves_Farm · Aug 20, 2018

We’re you ever able to get the second opinion? What was the final result? Mine is not nearly that bad, but I’d be interested to know what came of it.

Thanks