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I have a 4020 diesel that has developed an annoying habit of veering off to the right when driving. If you are quick and turn left it will straighten up but obviously it is dangerous on the road. When i start it and it is stationary it turns to the right on its own. Any ideas what is causing it? I am thinking a seal or ring has failed somewhere but i have heard that it is a tricky job refurbing the steering valve block? New to this site so hello and hope you can help.
 

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Welcome from WV.

The valve should not be to hard to rebuild for some one that is moderately mechanically inclined. I would suggest ordering the service manual before you start.


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Welcome from WV.

The valve should not be to hard to rebuild for some one that is moderately mechanically inclined. I would suggest ordering the service manual before you start.
:laugh: I take it it you've never seen the guts of a JD steering valve. Back when I was a JD dealer service manager I had several mechanics that couldn't get the valves adjusted correctly the 1st time and they had to REDO their valve adjustments again. The 4 valves inside require a special adjusting plate plus dial indicator to get correct clearances. Plus I think the problem is leaking o-rings in the steering motor which can be replaced by removing frt axle & one side frame.
 

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Welcome from Ohio.:greentractorride:
 

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I was going on my recollection of the tech manual for 318 and figured they would be about the same.
The steering valve on a 4020 is a completely different animal. I would go as far as saying it's like being in a different universe.
 

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Discussion Starter · #8 ·
:laugh: I take it it you've never seen the guts of a JD steering valve. Back when I was a JD dealer service manager I had several mechanics that couldn't get the valves adjusted correctly the 1st time and they had to REDO their valve adjustments again. The 4 valves inside require a special adjusting plate plus dial indicator to get correct clearances. Plus I think the problem is leaking o-rings in the steering motor which can be replaced by removing frt axle & one side frame.
Thanks Jim, will do o rings in steering motor and see if it does the trick.
 

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Steering

Hello to TX Jim, Newbie here, I have a similar steering problem. I was told to unhook the hose from the front steering section at the top of the hydraulic cooler tower and plug the nipple quickly as it will leak at top of tower. Then put hose in can and let it drain. Then start tractor and turn wheel to the right and see how much oil comes out. Turn to the left and see how much oil comes out. If it's just a few drops, the front steering section is OK, if there is a stream the front section is not good. You should have an assistant to do this.

I've explained my steering to some service mgr's, ie. locking wheel,wont turn, when turned to the right, wheels following steering wheel turn some time later by as much as a few to 5-10 seconds(kind of a guess). This happens on startup after sitting even a day. Have changed hyd fluid, filter, and tranny screen was clean. This is a 69 3020.

I was also told that bleeding the steering valve is also accomplished whenever the steering is at full left and right and it's not necessary to do a manual bleed of the steering valve.

3 service mgr's have said its the steering valve block under cowl. Please comment on this if you would be so kind. Thanks
 

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billyboy
It's been since '87 since I was a dealer service manager plus I don't have access to a 4020 tech manual so my diagnostic memory is limited. I think steering motor in frt is your tractors problem but I will ask a good JD technician friend of mine for correct answer This technician repairs enough of the JD hyd components that he built a super nice test stand to bench test the repaired components before installation or shipment.

Update
I sent tech an email with your question.
 

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billyboy, I am anxious to hear what TxJim's friend says to see if he agrees with me. In my experience, your symptoms are usually caused by the front steering motor. Have you tried the test by unhooking the steering motor bleed line? Your symptoms can also be caused by worn seals in the steering valve. With these symptoms, I usually do the leak test at the hose on the oil cooler, although it is not a absolute test result. I have found worn seals in the steering motor even when the leak test is inconclusive. My recommendation would be to reseal the steering motor even if the test shows OK. It is cheaper and easier to repair. Plus in my experience, it is the problem at least 75% of the time.
 

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I did the leak test at the hyd. cooling tower by unhooking the hose from the front steering motor and putting it in a can and then started tractor, 69 3020, turning wheels first to the right and then to the left and I got just a few drops of oil with each direction turn.

I'm hearing and reading that it's the front motor or the steering valve, would just like to know which it is for sure if at all possible before I tear stuff apart.
Hopefully TX Jim will get something more on this,,, I'm a bit concerned about driving into the ditch sometime if it all goes south suddenly, It works ok after it's run for a minute or two.


Thanks for the reply
 

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My tech friend sent me his test stand photos but forgot to answer my power steering question but I'll ask him again. Here's his test stand which I wish I had access to one similar to it when I was service manager. IIRC the yellow guard covers the drive shaft from electric motor to hyd pump.
 

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Thanks for the time and effort.

Today I tried to bleed the air at the steering valve, there were air bubbles for a bit and it was foamy,but the bleeding went along as anticipated. About the 3rd left to right pass in the bleeding process, the steer wheel locked when i tried to turn it as the oil flowed smoothly from the bleeder. Closed the bleed valve and it steers like it should.

This tractor has had a loader on it forever. When you turn to the left/right stop there is a physical lift of sorts on the front wheels like a bit of a slope up at the end of it's travel, or a pitch shift. I can feel and see the wheels do a shift but I can't explain what the heck is causing it or what is happening.
I grew up on 2 & 4 bangers, have run everything since. I'm use to wheels that turn smoothly one side to the other.

Guess I'll take a look at the front end. Thanks,
 

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I'll bet the knee has had the angle altered from heavy FEL loads. I've seen gussets added to this area for extra strength to help eliminate this problem or later model(42330/4430) frt ends utilized.
 

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I did the hydraulic/air bleed at the steering motor back on the 18th of the month and I let the tractor set for a few days between each startup and the steering worked just fine on three tries now. Do you suppose that was the trouble with it or will the steering problem come back to haunt me again? Any thoughts would be appreciated.

Tex Jim, If you should add to this could you tell me where and what the knee is on the front steering you mentioned in your last post. Thanks,
 
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