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  1. #1
    Super Member Highbeam's Avatar
    Join Date
    Feb 2005
    Posts
    5,039
    Location
    South Puget Sound, WA
    Tractor
    Kioti CK30HST

    Default 3pt oscillation- MLS valve?

    I have another issue with my machine and I promise to try my best to keep it minor.

    First thing in the morning when first starting up the tractor and beginning to unload it from the trailer I have begun to get an updownupdown of the 3pt hitch when I raise it up. I always wait a couple of minutes to begin to let the tractor warm up before I back it off the trailer so hydraulic pressure is established and the ambient air temps are 50+. The 3ph smoothly raises to the set point and then bang bang bang up and down a few inches. I set it down and try again in a minute and eventually this entirely goes away when warm and works as normal for the rest of the day. When I set the 3ph all the way down it acts as normal. Fairly minor inconvenience but obviously not right and since my machine was going to the dealer I had him check into it along with replacing my cinematic on the loader control.

    I described this to the dealer mechanic and he tried to fix it. The labor write up described his efforts as adjust, then remove, clean, reinstall, and readjust the MLS valve. I don't know what MLS means and am fairly ignorant of hydraulics for the 3ph.

    The 3ph raised and held when he test ran it to show me. He also said that he wasn't sure it was totally fixed and that he could order a new MLS valve for replacement the next time I am scheduled to go in which should be in 3 months.

    He did the MLS work with my boxblade attached. I did some blading and burning after retrieving my tractor and then went to mow my fields the same day. With the mower on the 3ph the oscillation is very rapid but smaller when the machine is warmed. RPM changes make it worse at lower RPMs and almost go away at high.

    The part that bothers me is that it feels like the 3ph is always fighting itself. Like when the 3ph is raised and held in position the engine is doing some work, you can hear the engine loaded. When I set the 3ph implement on the ground, the engine is unloaded and gets quieter. I worry that the MLS was adjusted to apply hydraulic pressure against itself to fight the oscillation and now it is always loading the hydraulics when an implement is off the ground.

    Another symptom. If the 3ph implement is raised and then I use the loader to lift something, the 3ph lowers a few inches and then comes back up when I unload the loader.

    I worry that the constant hydraulic pressure will overheat the fluid or cause other damage to the system. I do not recall the tractor engine laboring to simply hold the boxblade in position and certainly don't remember the boxblade dropping a few inches when hydraulic demand was placed on the loader.

    Is this an emergency type deal or is it fine for three months? I reach down every now and then and feel the HST filter for temperature and it never got too hot.

    Is this something that a mechanic really needs to be good at to handle? Please tell me what you think might be going on.


  2. #2
    Super Member Highbeam's Avatar
    Join Date
    Feb 2005
    Posts
    5,039
    Location
    South Puget Sound, WA
    Tractor
    Kioti CK30HST

    Default Re: 3pt oscillation- MLS valve?

    I got to thinkning that this is more of a generic question and will repost it in the repair section where maybe someone will be familiar with it. Thanks for looking.

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