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  1. #1

    Default Hydraulics Diagnosis

    I have a John Deere 950 with a third-party loader of unknown make. I've been experiencing a hydraulic problem, and I'd like to ask for any suggestions. I have the JD service manual, and think it's quite good, but when it comes to the hydraulics I just don't have all the special test equipment that seems to be at the core of the troubleshooting section.

    The FEL and 3pt operation has been slow, jerky, and getting worse over the last few weeks. This past weekend operation was so very slow that I didn't even try to take it out and do any work. This is Alabama, so it's pretty hard to blame it on cold. Besides, I've used the tractor with snow on the ground and the ground itself frozen, so temps in the 50s shouldn't be causing any trouble.

    Here's what I know, in order that it comes to mind:
    1. Slow and jerky operation raising either the FEL or 3pt (box blade). Lower just fine.
    2. Dumping and curling are also slow and jerky. Sometimes when dumping the bucket just stops and won't go any farther. If I curl and dump, curl and dump, it will eventually go on past that point like it should.
    3. On a couple occasions when I put the bucket on the ground and then try to dump, an operation that normally picks the front wheels off the ground with no trouble, I notice that the bucket forces the loader arms up instead of raising the tractor. Then if I lower the arms, there's a long wait when it seems like nothing is happening, but then it will very slowly lift the front wheels.
    4. I don't have a float position on the FEL.
    5. I've tried just sitting and running the FEL and the 3pt up and down, thinking maybe to work the problem out. This has grown less and less effective (it takes longer and longer to get to smooth operation). Weekend before last it never did smooth out in 2-3 hours operation. Transmission was warm to the touch. Transmission is also the hydraulic reservoir on this tractor.
    6. I use JD's recommended fluid, and the level's where it should be.
    7. New fluid and filters about 50 hours ago. That's supposed to be a 600-hour service interval.
    8. I don't hear the relief valve open while these symptoms are occurring.
    9. I have noticed a hissing sound, and this weekend found that it seems to come from the hydraulic pump, or at least that area.
    10. System relief valve is at the rockshaft.
    11. Someone suggested air in the system, but I can't figure how it would get there, because I haven't had the system open except at the dipstick since before I serviced the filters 50 hours ago. And if air were in the system, I thought all the raising and lowering would work it out. Instead things are getting worse.
    12. Engine starts right up and runs fine, doesn't seem to be loaded or anything.

    That's all I can think of. Any hints, suggestions, questions of symptoms I may have missed?

    Thanks,

    Steve

  2. #2
    Super Star Member RoyJackson's Avatar
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    John Deere 4400 MFWD, Deere 855D UTV, Z920A Zero Turn Mower and assorted implements

    Default Re: Hydraulics Diagnosis

    It sure does sound like air in the system.
    I've no idea what would be involved in bleeding your system, but I strongly suggest you replace the hydraulic fluid (might be worthwhile having the system flushed, as well) and the filter.
    Unlike liquids, air compresses... That could explain the jerky and slow motion you've described.

  3. #3

    Default Re: Hydraulics Diagnosis

    Check for a suction line leak, it may look like a small amount of fluid or build up in the area of the leak. It also could be the hyd pump is going out. Both of these things can cause oil foaming hence the air in the sytem causing what you describe when curling the bucket against the ground and the loader boom moving up. What does the fluid look like after you run it for a while? If it looks milky then you have air. It could also be water contaminated. The best way to tell the difference is to drain some out. Let it sit for a while (sometimes it takes till overnight) If it clears up and there is no water at the bottom of the container then it's just air. If there is no obvious suction leak and your filters are clean (you did check/clean the suction filter located at the left rear side of the tractor) then the problem could be the hyd pump.

  4. #4
    Gold Member
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    l245dt

    Default Re: Hydraulics Diagnosis

    i am by far no hydro exert but to mee sounds as if the pump is going out

  5. #5
    Epic Contributor Soundguy's Avatar
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    ym1700, NH7610S, Ford 8N, 2N, NAA, 660, 850 x2, 541, 950, 941D, 951, 2000, 3000, 4000, 4600, 5000, 740, IH 'C' 'H', CUB, John Deere 'B', allis 'G', case VAC

    Default Re: Hydraulics Diagnosis

    That suction filter is a must, for cleaning. We were experiencing problems on my fathers jd 2240.. seems the mechanic had always been servicing the regular filters, but never pulled the suction side 'tube'.. was nearly solid...

    This sounds almost like a started out pump... that is bad... as it will cause cavitation... and cavitation will eat a pump up quick.. sounds like this may have already happened to some degree.

    Soundguy

  6. #6

    Default Re: Hydraulics Diagnosis

    Thanks for the suggestions, guys. I do know about the suction filter, and had it out and cleaned it when I changed the fluid 50 hours back.

    I'll be:
    1. Looking for suction line leaks. I did look for leaks a little Saturday, but can certainly look a little more and a little closer.
    2. Run it for a while and then drain some fluid for a look.
    3. Maybe pull the lines at the pump for a look at the o-rings.
    4. Worry about needing a pump.

    Thanks again,

    Steve

  7. #7
    Epic Contributor Soundguy's Avatar
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    Default Re: Hydraulics Diagnosis

    We'll be here, waiting to here what you found.
    Hopefully we can come up with a treatment for you... and hopefully it isn't expen$ive.

    good luck, and Happy thanksgiving to all!

    Soundguy

  8. #8
    Veteran Member
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    russellville, arkansas
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    Kubota M4900, B7510 and RTV

    Default Re: Hydraulics Diagnosis

    looks like its time to pull the filters and if your tractor has it, the screen: and see if theres anything there that shouldn't be; what you describe happened to me on my JD1020 when the brakes went bad and stopped up the screen and filters for the hyd system; but when i removed the screen and filters, it was pretty obvious what the problem was. are your brakes making any noise?
    heehaw

  9. #9

    Default Re: Hydraulics Diagnosis

    No, no brake problems.

    Progress for tonight: Wiped all the lines down in hope of making any leak a little easier to find. Ran the tractor a little more than an hour, raised and lowered the FEL and 3pt a few times, shut down and drained out about a quart of hydraulic fluid. The fluid was full of little air bubbles, and may be a shade darker than new. Not sure about that. Left the jar of fluid to sit and see if it seperates while I do Thanksgiving.

    My next step, I think, will be to drain the fluid and have a look at the filters.

    Thanks,

    Steve

  10. #10

    Join Date
    Sep 2002
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    Location
    Ohio
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    ford 3000,case SI..Just purchased a 404 Futon (40 hp 4wd) with a koyker FEL

    Default Re: Hydraulics Diagnosis

    Steve,Kinda courious as to what you came up with.My Ford 3000 has the same kinda problems.ie: conflict between the loader and 3 pt.I thought my problems was the slave block for the loader...o-rings and ports seemed clean.Next step is removing the suction filter in the houseing.If not that will check hoses for a switched hose...last resort (ulp) would have to be something internally for the 3pt (bypassing)...Sid

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