John Deere 710D rear bucket problem ...

[CoOlSlY]

I am planning to purchase a John Deere 710D 1993...

The rear digging bucket will move automatically to the left or right when not operating (ie. when the ignition is switched off, after a few minutes if the pin is not installed). Like if it loses all pressure and moves automatically, very slowly. Otherwise, when operating, everything is normal but if I shutdown the backhoe, it will go left or right after a few minutes...

Would it be more the control valve or a cylinder?

The control valve seal have been changed and the problem is still there so wondering if I should just skip the buy or if it's a minor problem.

Thank you

 

[stinky64]

That's an injury or lawsuit waiting to happen....

 

[Delmer]

It wouldn't bother me, you should always leave the attachments on the ground or locked.

I'm not sure which control valve seal was changed, I 'd have to look at how that valve functions, but it doesn't sound terribly serious in the scheme of what goes wrong with old backhoes...

 

[Willie B]

I am planning to purchase a John Deere 710D 1993...

The rear digging bucket will move automatically to the left or right when not operating (ie. when the ignition is switched off, after a few minutes if the pin is not installed). Like if it loses all pressure and moves automatically, very slowly. Otherwise, when operating, everything is normal but if I shutdown the backhoe, it will go left or right after a few minutes...

Would it be more the control valve or a cylinder?

The control valve seal have been changed and the problem is still there so wondering if I should just skip the buy or if it's a minor problem.

Thank you

Some of the sections in the backhoe valve have port relief valves. These are more important in boom valve for example. The boom cylinder is pressure relief protected at say 3500PSIG. Lift a heavy object, the valve then closes. If you then push your crowd out, or extend the dipper, leverage on the boom cylinder will increase well beyond 3500 PSIG. A port relief allows that excess pressure to return to the filter.

Port reliefs are 1.5" long, 1" diameter, but cost more than gold. They are no longer available for a 410C, but I did get a rebuild kit.

 

[Tinkerer]

Not everyone that takes those valves apart re-assemble them correctly.
I had an experience with a loader valve. Some dummy left a spring out of it after installing new O-rings.

 

[Willie B]

If I understand the valve there are several points where leak by could happen. I believe a tiny hole is normally plugged with a needle held in place by a spring. The force holding the needle in its seat is adjustable.
When high pressure pushes the needle out of its hole, a bit of oil flows into a cavity & lifts a piston. This opens a larger valve, letting high pressure oil flow from a hydraulic cylinder to the filter, then back to the transmission.

 

[CoOlSlY]

I went to do an extended test on the backhoe... It's not as bad as the seller said (looks like an honnest seller). The rear backhoe will move left or right randomly if the lock pin is not in place and that you move the backhoe for about 100 feet even on a not bumpy terrain. When the backhoe is not moving the boom will not move. It's when moving and hitting a little bump, the boom will move left or right! I read all the answers but where should I look at in the first place for the problem to see if somethings wrong?

 

[CoOlSlY]

I went to do an extended test on the backhoe... It's not as bad as the seller said (looks like an honnest seller). The rear backhoe will move left or right randomly if the lock pin is not in place and that you move the backhoe for about 100 feet even on a not bumpy terrain. When the backhoe is not moving the boom will not move. It's when moving and hitting a little bump, the boom will move left or right! I read all the answers but where should I look at in the first place for the problem to see if somethings wrong?

 

[CoOlSlY]

Sorry for the double post, it seems I don't have the option to delete the duplicate

 

[Delmer]

at this point, I'm not sure it wouldn't have done this the day it left the factory. It could be much worse because of the hammering from slop in the pins causing the reliefs to "cushion" the blows from rocking back and forth.

I guess you could raise one side higher than the other and stick the boom straight back and see how long it takes to swing over to that side, then try the other direction with the same angle. If those times are fairly close, and not unreasonable to use the backhoe, then I don't see a problem.

They put a lock on that for a reason.

 

[Willie B]

You might have a total internal piston bypass of both swing cylinders. It could be a leak in the swing valve, but I believe you would experience other symptoms, like weak backhoe function. I expect you will find a leaky port relief. They are the hex bolt on top & bottom of all the sections in the backhoe control valve.
In my case, I had a tiny bit of debris jamming the needle valve open. Refresh kits I believe are available from John Deere. Mine cost about $53. plus shipping.

 

[Delmer]

If it is only one port relief that's bad, then the backhoe will swing/leak off faster one direction than the other. I mean when it's not supposed to be swinging, like you're describing.

It would only take one leaky hydraulic cylinder for it to move, they're plumbed together.

 

[BarryB]

I had basically the same problem with a 410B. It would swing slowly to the "low" side, running or not. The swing cylinders are hydraulically "in series" thus one cylinder's leaking piston seal can cause this. I rebuilt one swing cylinder and it solved the problem.

 

[Delmer]

I had basically the same problem with a 410B. It would swing slowly to the "low" side, running or not. The swing cylinders are hydraulically "in series" thus one cylinder's leaking piston seal can cause this. I rebuilt one swing cylinder and it solved the problem.

If you want to test for this, start the backhoe up cold, extend the backhoe and dig the bucket into the ground so it won't swing. Then at low idle, hold the swing all the way to one direction for thirty seconds, then shut it off, and hop off and feel the valve and cylinders for a warm spot, if you find a warm spot, that's your leak. If you do this test on a damp misty morning when the backhoe is covered in dew, you might see the part "steaming".

 

[BarryB]

I like it!!, thanks. I wonder what the fix turned out to be with CoOISIY?

 

[CoOlSlY]

If you want to test for this, start the backhoe up cold, extend the backhoe and dig the bucket into the ground so it won't swing. Then at low idle, hold the swing all the way to one direction for thirty seconds, then shut it off, and hop off and feel the valve and cylinders for a warm spot, if you find a warm spot, that's your leak. If you do this test on a damp misty morning when the backhoe is covered in dew, you might see the part "steaming".

Just want to make sure I do it properly, I dig a hole but leave the bucket under the "soil" so it won't move (not just putting the bucket on the ground). At low idle, I hold the swing all the way in one direction, it will not move since it's underneath the "soil" correct? I then shut it off and check for a warm spot and if there's a leak, it should be warm (?)

 

[CoOlSlY]

I like it!!, thanks. I wonder what the fix turned out to be with CoOISIY?

For now, the problem is unsolved. The guy selling the backhoe said he changed all the seals (internal and external) in one swing cylinder and he changed also the main control valve seal. He opened the second swing cylinder but didn't had the seals but said they were in perfect condition and suspect that one of the cylinder might be "oval" (is it bs, idk). So, while everything points to a swing cylinder seal, the seller is saying he looked at it and *he's* saying it's not the seals.

 

[Delmer]

yes, it's a closed center system so the system is under standby pressure all the time, any leak will create heat because it's full pressure. The engine won't have any load if nothing is moving. The bucket could be stuck in the dirt, or leaned against a stump, there's not that much force with the bucket all the way out.

On second thought, maybe MG or somebody will correct me if the port relief is lower than the standby pressure? that would cause the valve to heat up even with everything correct, it would not affect the cylinder. The cylinder will not heat up unless it's leaking, whatever the valve is doing. I thought the boom down was the only port relief that was lower than standby, but I don't have a book handy, and it wouldn't be a 710 book anyway.

 

[mg2361]

correct me if the port relief is lower than the standby pressure? that would cause the valve to heat up even with everything correct

Correct. Standby is 2550 psi and the swing port relief is supposed to be 2750 psi. If a port relief is low it would heat up at that spot. Also it would only drift one direction.

the seller is saying he looked at it and *he's* saying it's not the seals.

I have seen many swing cylinders with a piston seal that looks good but the expander ring under the piston seal is shot. If it is apart then repack it.

 

[Willie B]

yes, it's a closed center system so the system is under standby pressure all the time, any leak will create heat because it's full pressure. The engine won't have any load if nothing is moving. The bucket could be stuck in the dirt, or leaned against a stump, there's not that much force with the bucket all the way out.

On second thought, maybe MG or somebody will correct me if the port relief is lower than the standby pressure? that would cause the valve to heat up even with everything correct, it would not affect the cylinder. The cylinder will not heat up unless it's leaking, whatever the valve is doing. I thought the boom down was the only port relief that was lower than standby, but I don't have a book handy, and it wouldn't be a 710 book anyway.

410C has 7 port reliefs set at lower, if I remember correctly. The boom sag port relief is the same part but it would be factory set at 4500 so it is a different part number.