Weak rear bucket on JD 710D

[CoOlSlY]

Well well well... When we first tested the backhoe, we were unable to dig since the land was frozen for 4 feet. So we bought this good old and heavy JD 710D

Now that winter is over, our well guy had to dig with the 710D and he said he personnally had experience on the JD 710D so, great, go ahead! He tried to dig but he was not able to fill the rear bucket, the JD 710D was weak weak weakkkk. The front bucket has no problem lifting a bucket full of rocks but the rear end is weak. I heard people putting shims somewhere, I would have a guy test the pressure and have it do the job but I would like to do some troubleshooting by myself first. Is it common on those machines?

Thank's in advance

 

[Delmer]

Can you narrow it down to which function, or even which direction is weak? And how do you define weak? that is a heavy machine, so it might not throw itself around like a lighter machine will. It should lift the rear end and slide around side to side and forward and back with the stick straight down.

You do understand that if you bury the bucket it will just sit there with no load on the engine, controls doing absolutely nothing, no squealing, not even trying. That's the nature of the closed center system.

 

[CoOlSlY]

You are right Delmer with a bit of a lack of details :|

When I say weak, for example, if we try to "dig" (boom down), it's unable to dig into sand for more than a few inches for example. Then, let's say it's 1/4-1/2ft down in the sand, if I try to bring the bucket towards the backhoe (pull), it cannot and if I want to curl, it will not curl either, no noise whatsoever though. It will if I take 1/4ft in the sand but otherwise, it won't go deeper that's why i'm saying it's really, realllllly weak and don't know where to start off, I just want to do the basic troubleshooting before calling a professional.

 

[Delmer]

Sounds like the stick in has no power. Does the boom down lift the machine off the ground with the stick vertical? Does the bucket curl even after the stick has stopped with boom weight on the bucket? or maybe that's what you mean by won't curl. I assume the stabilizers have no trouble lifting the wheels clear of the ground with the backhoe stowed? The swing is supposed to be weak so ignore that.

After you figure out what functions are weak, I'd sit there with the stick buried and stick in "stalled" for thirty seconds, then shut the engine off, jump out and feel the cylinder for a warms spot, then feel the control valve for a warm spot. The warm spot is your leak.

 

[CoOlSlY]

1st: The stabilizers have no trouble lifting the wheels of the ground
2nd: When doing "boom down" it will lift the machine but it's still very weak when digging but I understand what you mean. I will test again. When you say "stick buried and stick in "stalled" for thirthy seconds, what to you mean?

Hopefully it's not the control valve (body valve), the seals were changed lately (like, 10 hours ago). I thought by reading it could be the relief valve (?)

 

[Delmer]

Try to dig with it and when the stick in/crowd function stops, just hold the valve open for thirty seconds, then shut off the engine, jump out and see whats warm.

If this was an open center machine, the hydraulics would be going "over the relief" meaning they're pumping oil through the relief valve when you hold a function stalled. With this closed center system, the pump should supply the standby pressure, but stop pumping volume as the oil flow stops. No oil through the relief valve, no heat generated. If you find heat, that's the leak. If you find no heat, then we look at the pump pressure.

 

[mg2361]

If just the whole backhoe is weak, then I would suspect a bad system relief valve in the inlet section. It can only be checked with a remote pump. The picture below may not be your serial number but should represent a general location regardless of the serial.

 

[mg2361]

I did not see that you could lift a pile of rocks with the loader, so disregard my last post. Too long of an explanation as to why the relief may have been the issue even though it affects both loader and backhoe.

 

[CoOlSlY]

OK, I can definitely take a pill of 0-2" with the front bucket. Maybe not completely full since i'm not an expert but it does seem to have no problem lifting 3/4 of a bucket full of rocks. I will look with the trick where it's hot and start from there. I will also write to the seller to see if he can do something about it after I find what the problem is...

 

[CoOlSlY]

Just wondering, what can we rule out if the front loader is working properly? I mean, can we rule out the pump and the body valve itself and it's probably just a seal somewhere?

 

[Delmer]

If the front loader is fast, smooth and strong, at idle when cold and hot, then the pump should be OK, and the backhoe valves shouldn't be leaking too badly. If the system pressure drops, then the priority valve will cut off flow to the loader valve to preserve pressure for steering and brakes, but the backhoe valve is not cut off (so if you use the backhoe while moving, you will lose steering and brakes).

I can't rule out anything else. and that bit is wishful speculation.

I'd try the heating up test when it's cool, it will be easier to feel or see the warm spot.

 

[lantraxco]

Not familiar with the 710D but most of the Deere hoe's had a priority valve that controlled pressures for some functions?

 

[mg2361]

I would still start with the pump charge and standby pressure tests regardless of what the loader is doing. Then we move on from there.