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  1. #1
    New Member
    Join Date
    Sep 2008
    Posts
    8

    Default L4610 3 POINT HITCH PROBLEM

    I recently purchased a kubota L4610HST with 330 hours on it. Used the tractor for a month and everything was working great so I decided to purchase a new Kubota front end loader. I installed the loader and added almost 1 gallon of super UDT Kubota hydraulic oil to top of the system after running the loader long enough to fill the lines and cylinders. Used the tractor for about a hour one evening (both the loader and three point hitch) and everything worked fine. I was using the tracor tractor over the weekend to move dirt and the boom lift on the loader quit working correctly. It would only lift a few inches then stop and would only lower if the valve was put in the "float" position. The boom functions would work if the control valve handle was pulled/pushed at an angle which would enable a bucket function at the same time as a boom function. Example- It would lift the boom and curl the bucket at the same time; but would not lift only. It would quit lifting the boom as soon as the bucket had reached the end of its stroke. The bucket funtions continued to work fine. I removed the plastic cover on the valve thinking the linkage was messed up; but it was working correctly. Then I iunhooked the the hydraulic hose on the valve with the quick disconnects and then put them back on. Started the tractor and the front end loader was working correctly; noticed the 3 point hitch arms were all the way down and the selector lever was in the up position. The 3 point hitch arms will not raise!! I completly unhooked and the hydraulic hoses going to the loader control valve from the tracor and re-installed the factory plugs. Now the loader is not attached to the tractor hydraulic system. The 3 point hitch arms will still not raise. This is with no implement attached. You grab the lift arms and raise them by hand with no resistance. With the loader attached, there is plenty of hyd. pressure, the loader will pick the front of the tractor off the ground. Help greatly appreciated.

  2. #2
    Gold Member
    Join Date
    Mar 2005
    Posts
    418
    Location
    Woodbury, CT
    Tractor
    B3030

    Default Re: L4610 3 POINT HITCH PROBLEM

    I am no tractor expert, but I can offer that my B3030 manual states that after you change the hydraulic fluid, if the 3 pt. hitch will not function, get air out of the hydraulic system by turning the tires from side to side? Just a thought. Good luck.

  3. #3
    Elite Member rbargeron's Avatar
    Join Date
    May 2000
    Posts
    2,540
    Location
    MA
    Tractor
    L5450, L48, L3250, L345

    Default Re: L4610 3 POINT HITCH PROBLEM

    Couple questions - in disconnecting/reconnecting the hydraulic lines did you change the position of selector valve on the hydraulic block under the tractor. With all ports plugged the slot needs to be horizontal for the 3-point hitch to get power. The lift function symptoms sound like a pair of hydraulic lines are switched from where they should be. It worked for a while untill the air was out of the cylinders but now it's getting blocked?

  4. #4
    New Member
    Join Date
    Sep 2008
    Posts
    8

    Default Re: L4610 3 POINT HITCH PROBLEM

    Yes- I did change the position of the selector valve on the hydraulic block back to the original postion when I plugged the ports. The arms will not raise. I hooked the loader lines back up to the hydraulic block, changed the selector valve, and the loader will work fine; but no 3 pt hitch arms. After mounting the loader and adding hydraulic oil, I used the loader and 3 pt hitch for at least and hour one day and 15 to 20 minutes in another day before I started having problems with the loader and then the 3 pt hitch.

  5. #5
    Elite Member rbargeron's Avatar
    Join Date
    May 2000
    Posts
    2,540
    Location
    MA
    Tractor
    L5450, L48, L3250, L345

    Default Re: L4610 3 POINT HITCH PROBLEM

    This is a head scratcher.

    The 3ph gets power either straight thru the block or from the power-beyond hose on a loader valve, if installed. If the loader valve work ports were connected wrong that might explain the interaction of boom and bucket functions. But the fact that it all worked fine for a while points to something coming loose inside the loader valve and moving to block flow. Even so the 3ph should still work fine, especially when you have it routed straight thru the block.

    Ok some dumb questions (don't be offended) Is the loader valve a kubota model? Was it new? Anybody try to covert it to closed-center for a John Deere application? Is the hose back to the hydraulic block really the power-beyond hose? What position is the draft lever in? Is it's linkage ok? Is the 3ph lift lever linkage ok? Does the hyd block selector valve feel ok? (maybe try moving it to see what effect you can get). Does this tractor have any remote hydraulics? What type? How are they plumbed?

    Back on the interaction of boom and bucket, Kubota's loader valves have an internal regenerative port that makes use of pressurized oil in the cylinders to augment the supply. The result is faster loader operation. If the main exhaust flow path is blocked, the regen circuit would be the only path available - so that sounds like what you were seeing with the loader. Not sure how a problem like that could "come and go". And I sure don't know how it could affect the 3ph.

    I think we need MadReferee for this one.

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