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  1. #1
    Silver Member
    Join Date
    Oct 2001
    Posts
    210
    Location
    Placerville, CA.
    Tractor
    1998 New Holland 1920

    Default Perplexing Hydraulic Problem

    I had this posted in NH Owning Operating and Thought I'd try it here.

    Fortunately AFTER I dug my trenches, my 757C backhoe lost hydraulic power slowly to the point of nothing in just a few minutes. Interesting thing is, the front loader still works. Redirected the Backhoe line back to the 3 Pt. Lift and it doesn't lift either.

    So I thought, perhaps one of the lines was clogged up, but it appears that there is pressure coming out of the manifold line that the FEL lines come from as well (How much I don't know). Fluid level appears to be fine so what am I missing here? Can anyone give me a pick list of items to go through in succession? Thanks in Advance TBN'ers.

    Todd
    Placerville, CA.

  2. #2
    Silver Member
    Join Date
    Oct 2001
    Posts
    210
    Location
    Placerville, CA.
    Tractor
    1998 New Holland 1920

    Default Re: Perplexing Hydraulic Problem

    Further Diagnosis: After testing various things, The 3 Pt. Lift does lift if I crank it up to 2500 RPM's but even then it is not fast and can easily be stopped by hand. The backhoe works a little bit but not all levers and does not generate enough power to lift the main boom.

    My thinking at this point is that it could be something as simple as changing the Hyd. filter, which I'll do tomorrow or it could be in the manifold or hose that services both the 3 Pt. and the Backhoe. We'll see.

  3. #3
    Silver Member
    Join Date
    Oct 2001
    Posts
    210
    Location
    Placerville, CA.
    Tractor
    1998 New Holland 1920

    Default Re: Perplexing Hydraulic Problem

    OK, this is still stumping me. I want to the NH dealer and picked the mechanics brains. They said the following:

    Overfilling the Hyd. Fluid could not cuase this problem.
    The Hyd. Filter, which I changed could not cause this problem and incidentally, did not fix it.
    They suggested adjusting the set screw which directs fluid to the Power Beyond or to the FEL, no impact.
    Last but not least, remove the manifold that drives the FEL and Power Beyond and check for blockage from dirt, debris, teflon tape etc...There are not alot of moving parts in it they say, but it had them somewhat stumped as well.

    Is this the next step? I thought I'd have an easy diagnose and fix but alas, it's not.

    Todd in Placerville

  4. #4
    Veteran Member
    Join Date
    Sep 2000
    Posts
    1,371

    Default Re: Perplexing Hydraulic Problem

    Todd,
    I don't know anything about your tractor or backhoe, but have you tried disconnecting and reconnecting the "quick disconnects for the hoe? If you have the hydraulic schematics look for common elements for the hoe and the three point that are not shared by the loader. Like perhaps the selector valve or relief valve.
    Al

  5. #5
    Silver Member
    Join Date
    Oct 2001
    Posts
    210
    Location
    Placerville, CA.
    Tractor
    1998 New Holland 1920

    Default Re: Perplexing Hydraulic Problem

    Believe me, I've coupled and uncoupled numerous times so I don't think it's a jammed quick connect in the hose. The common element appears to be pointing to either the manifold that power comes into for the FEL and also provides power beyond or the primary power beyond hose.

    At this point, I fortunately have use of the FEl as I have to get Sand into my power trench for final inspection next Monday. Then I can push the dirt back and then I can start tinkering with the problem. Thanks Twinkletoes. Input of any kind is appreciated at this point. I'm determined to figure this out without having to go to the shop with tractor in tow!

  6. #6
    Super Star Member Egon's Avatar
    Join Date
    Aug 2001
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    17,782
    Location
    Nova Scotia, Canada

    Default Re: Perplexing Hydraulic Problem

    More questions but no answers.
    Do the FEL and Three point run off the same hydraulic system?
    Is it possible for the three point controler to have gotten out of adjustment and allowing fluid to bypass? Example; if the lever on my tractor gets stuck in fully up for three point all the fluid is bypassed and nothing works.

    Egon

  7. #7
    Silver Member
    Join Date
    Oct 2001
    Posts
    210
    Location
    Placerville, CA.
    Tractor
    1998 New Holland 1920

    Default Re: Perplexing Hydraulic Problem

    Egon, Thanks for chiming in. Yes they run off the same Hyd. Sys. Anything is possible but I can honestly say I don't know if the 3Pt. may have gottn out of adjustment. When the backhoe is attached, the 3 Pt. is in it's lowest position. In order to get the 3 Pt. up after removing the backhoe, I rev her up to about 2500 and it slowly raises. Reving up this high also get's the backhoe to respond sloooowly and inconsistently. On this tractor, the power beyond comes out of a manifold that the FEL lever is on as well. One hose (power Beyond) comes out of this manifold/valve and is quick connectoed to either the 3 Pt. valve or the backhoe hose-Not both at the same time. This is what leads me to believe it's either the hose or the manifold.

    Do you think I could have blown an O Ring somewhere in the system? Friends say if this happened, I'd have visible leakage of Hyd. Fluid, which I don't.

    Still Stumped.
    Todd in Placerville

  8. #8
    Super Member
    Join Date
    Apr 2000
    Posts
    5,666
    Location
    Cedartown, Ga and N. Ga mountains
    Tractor
    1998 Kubota B21, 2005 Kubota L39

    Default Re: Perplexing Hydraulic Problem

    Todd, is it possible that a relief valve is stuck open? I am no mechanic, but I believe on my kubota the 3pt has a separate relief valve and that is the same system that runs the backhoe on mine. I could see how high RPM’s might let enough fluid flow to allow limited movement. Just another thought.

    Good luck,
    MarkV

  9. #9
    Super Star Member Egon's Avatar
    Join Date
    Aug 2001
    Posts
    17,782
    Location
    Nova Scotia, Canada

    Default Re: Perplexing Hydraulic Problem

    The fellow mentioning the relief valve just may be on the right track.

    Egon

  10. #10
    Elite Member
    Join Date
    Mar 2000
    Posts
    3,239
    Location
    Eastern Virginia
    Tractor
    EarthForce EF-5 mini-TLB (2001)

    Default Re: Perplexing Hydraulic Problem

    Todd - Your tractor has an open center hydraulic system. So, if there was a restriction in the circuit going to the three point hitch or the backhoe, the engine would be loading up and the relief valve would be opening to relieve the pressure, which you should definitely be able to hear. This would also be the case if one of the quick-connects were stuck. Since you don't have these symptoms, it's not that.

    Since there's no restriction, but almost no movement, either, there's almost no pressure getting to the back. We don't know if there's any flow or not - you could only tell that by comparing the temperature of the rear hoses with the front hoses (after warming the tractor up and using both ends a bit), or by taking the quick disconnects off the end, putting them in a bucket and having someone start the tractor for a few seconds, then turn it back off.

    The front end loader is working normally, correct? Therefore, you must have a normally operating pump. Also, the relief valve affecting the loader circuit must be working, as well. I don't know if your tractor has two relief valves, or one. If it has separate relief valves for the loader and rear system, then it's possible that you have a bad rear relief valve, but only if you have flow back there. If you don't have any flow at the back (remember, that's not the same thing as pressure), the problem has to be in the distribution block or front manifold, whichever you prefer to call it. If you do have flow, but no pressure, there's got to be a relief valve broken somewhere - and it has to be a different relief valve than the one that affects loader operation. (It could also be a spool that's broken, but you've confirmed that the same circuit is non-functional with both the three point hitch and the backhoe, so it's very unlikely that you'd have broken valves in both.)

    Now you're really confused, right? [img]/w3tcompact/icons/smile.gif[/img]

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