I bought a JD 310SE at an auction, that has a hydraulic problem. The backhoe seems to work to some degree, not optimal, but the loader will barely move. I'm aware that the SE, unlike the E has a two-stage hyd. pump that I believe works together with a switch on the seat in conjunction with a solenoid on the pump that increases the flow when you need it. Anyway, if someone has run across this issue before, maybe you could tell me what it was. If I don't hear from anybody, in the meantime, I will go through the regular things, suction strainer/filter, pump relief valve, pump worn out, control valve relief valves, to see if anything helps. I'm wondering also, if the pump is putting out too much pressure and it's opening the relief, in that case I should check the pressure that the pump is putting out. Thanks for any help. Craig
Start with the system relief. The SE backhoe had issues with the old style relief causing slow/intermittent/no hydraulics. It mounted in the backhoe control valve.
OK, so I'm straight, the relief that's on the hoe control valve will affect the loader hydraulics, because the backhoe is working, although maybe not up to 100%. Thanks, Craig
There is a serial number break for the SE which will make a difference on which hydraulic system it has and also determines which style of system relief it has. What is the last six digits of your serial number? Also how is the steering on this machine? Does the steering work with bucket empty and full?
mg2361, The steering seems to work ok and the backhoe works, although maybe not optimal. The loader takes 5 minutes to raise 2 inches off the ground and the hydraulic oil from the pump to the loader control valve, back through filter and back to tank gets extremely hot. Note that the rest of the valve is not getting that hot oil, so it doesn't get hot, so the oil is going from the pump to the inlet of the valve and back to the tank. I took two relief valves apart and cannot see anything wrong with either. After reading some other info on this, it suggested that the pump is operating at 'over relief pressure', so I assume, it's holding the relief valve open? The sn is 855593.
If it is only getting hot at the top section of the control valve then it would most likely be a relief valve or the priority valve is sticking/stuck. Does your oil get hot without moving any functions? Did you take the two stage relief out? That would be the system relief. It has a hose that goes into the end of it. It should be the one on the top left (rearward) (while viewing from the ground) of the control valve. Also does the backhoe still move with the seat facing front? The second pump in your hydraulic pump only moves oil to the backhoe when the seat faces the rear. That pump is not used for loader operation.
mg2361, The backhoe operates the same no matter what position the seat is in. The book says that when you turn the seat to the backhoe controls, that you will get the xtra flow and pressure from the pump's second stage. I believe the inlet part of the control valve gets hot without operating anything. I've looked into the valve that you are talking about, that is screwed into the top left of the control valve (inlet section) and has a hose attached to the other end which goes around to the bottom of the control valve. I took it apart but couldn't visually see any problems. Maybe the spring is just weak. The Deere dealer wants $500+ for it and I found another oem for $400. I just hate to spend that much, not knowing for sure that is the problem, but I'm running out of things to try. I might have to bite the bullet.
Take a look at the attachment. Check the Priority Spool ("C" in picture) to see if it is stuck. Careful, the spring is under tension. This spool is right next to the relief valve.
Also, make sure orifice "E" is in place inside the spool. It is threaded into place and may have come loose.
I'll check those couple things and let you know.
Pulled the spool out and see that it has a hole all the way through. There is nothing else there besides the spool and spring. Is there a pin that is supposed to block that orifice? If so, this one is not there. Thanks.
The orifice should look like a set set screw with an allen head drive to remove/install. If that orifice is missing that could give you some of the symptoms you are seeing. See attachment.
mg2361, It's possible that this is the problem. I don't see anything screwed into the orifice, like a jet or restrictor. It had what looked like debris in it. After pushing a rod through it, it looks like a straight, gun drilled hole all the way through.
Does have a spot within the drilled passage with threads? If so you may have to make an orifice from a set screw that would fit.
Thanks for the advice. I'll check. Couldn't see any threads at first glance.
I didn't have a chance to pull the spool to check for threads, but I shimmed the spool and was able to get the loader to operate, so I think the problem is the lack of an orifice, like you thought. I tried to get some info from the JD dealer as to the orifice or the thread size, so I could make one out of a set screw. They didn't have a clue & tried to sell me a priority valve for $2,050.00.
Well, we tapped the spool, because there were no threads left, and drilled a set screw and installed, like you suggested and we have a sellable machine. Thank you mg2361, for your help. Took some time, but saved a lot of $$. Almost bought a used priority valve for $1200 and a relief valve for $400.
Does this machine have auxiliary hydraulics, to run hammer or thumb? It sounds like a valve is stuck. Some times the aux is foot switch or pedal or switch on the dash. Have you plumbed in a gauge to the test port on the inlet section of the backhoe valve just below the relief? Also that micro switch under the seat, they break all the time. To test put the machine in fwd. and swivel the seat about 90 degrees. it the stop alarm comes when seat is swiveled switch is good. But I also kinda think that that 2 stage pump is active whenever the shifter is in neutral. Only on the E model. On the G-series they went to using the seat switch for the 2 stage pump.
We found that the .030" orifice in the priority valve spool was missing, therefore leaving a 5/32" hole through it.
I did not see an answer to the question before but is the bucket curl slow as well? or just loader lift? I have seen this issue with blown loader lift cylinder packings. Because they are hook together they will act weird.
Both loader functions were basically inoperable, but after installing the tiny orifice, it seems to be working ok.
Where is the loader priority valve located on john deere 310 SE backhoe,
It is on the loader control valve which is mounted on the frame under the right side step cover. The supply oil from the pump feeds the valve through the priority valve section.
I put a 5000psi gauge in the GP port and had backhoe at full throttle and I did the loader roll back and it read 2300psi and than I did the hoe lift and it read 2800psi. Did I check the pressures correctly to see if the hydraulic pump is going bad on mine.
Is any one still active on this feed. I have a 310SE with the same ( but worse ) issues. We sent this machine in and it worked for 6 months now it is back and all the same problems came right back. Front bucket will only lift with throttle , more throttle the faster it will go up. same with curl. Same with backhoe boom and down riggers. I just happen to notice that while holding curl and deadheading the rear boom seams to work fine. Let off curl and rear boom stops. The bottom section of the loader control valve was replaced by another shop and the valve body at the rear for the backhoe controls. Seams they just threw parts at it. (4 k worth) Everything I have read here seams to make me believe this is the same issue. Also the steering is effected it will not steer if stopped and only with throttle will it start to steer. The JD memo states steering would still function. Thanks
I got on here to research the exact symptoms you had Macktruck907, did you ever find out the issue?