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  1. #1

    Default Hydraulic pump cavitation

    What does it sound like? My Yanmar 2420D has almost no hydraulic function. When you raise the engine speed above idle the line exiting the hydraulic pump just buzzes with vibration. The buzzing feeling is way less when you touch the pump or the power steering proportioning valve the line connects to about a foot away but they are firmly mounted. From the diagrams I have I don't think the pump has a relief in it. I have recently clean the strainer and changed the filter with one that fits but has a much smaller micron rating. The fiter is on the suction side of the pump. I have been waiting for weeks for the correct filter from an online source but that's another story. When the hydraulics get really warm the lines jerk like the fluid is going though in spurts and when the loader does work it's motion is often quite jerky. Help, this is turning into the gray market nightmare people speak of. Any suggestions would be seriously considered and appreciated, thanks.

  2. #2

    Default Re: Hydraulic pump cavitation

    <font color="blue">changed the filter with one that fits but has a much smaller micron rating. The fiter is on the suction side of the pump</font>

    From this (the smaller micron size) I would suspect that you're starving the pump and are truly causing cavitation. A very bad thing for your pump as well as the rest of the system.

    <font color="blue">the lines jerk like the fluid is going though in spurts and when the loader does work it's motion is often quite jerky </font>

    Another indication you're restricting the flow to the pump.

    After saying all that. What was the initial reason for changing the filter? Were you having problems or was it just time?

  3. #3

    Default Re: Hydraulic pump cavitation

    Sounds like fluid starvation to the pump to me too. Of course it could be sucking in air on the suction side somewhere too. How is the fluid? how long has it been since it was changed ? Does it appear tan or cream colored ? This indicates water in the fluid. Bad thing. If you have a suction screen and a suction filter and the pump is starving. I think it would be best to remove the filter until a correct one is procured. Dirty fluid is better than no fluid to the pump. Best is not to run the tractor until the proper filter is obtained.

  4. #4

    Default Re: Hydraulic pump cavitation

    I bought the tractor in December and the hydraulics always took a long time to warm up, about a half an hour but I thought that was because of winter. When it recently got much worse and the three pt stopped raising I started asking more questions online. The hydraulic filter had been changed when I bought the tractor (about twenty hours run time ago), not with OEM but the commonly used "will fit" Wix/NAPA filter with too small a micron rating. It was suggested that could be the problem so I changed it again with what was available (NAPA) and it was somewhat better for a day only then back to nothing. After weeks of frustration with lame or no hydraulics I just want to make sure that I'm heading in the right direction. The tractor has OEM power steering that also has recently developed hydraulic leaks (possible caused by the pulsing pressure) that I'm struggling with but no manuals appear available that cover this seldom seen option. I also ordered a hydraulic pressure guage to try and figure out what is going on where. I did finally contact the vendor where I had placed the order for the OEM filter so hopefully it's on it's way soon. thanks

  5. #5
    Elite Member
    Join Date
    Mar 2002
    Posts
    3,451

    Default Re: Hydraulic pump cavitation

    If the problem started after you changed the filter.......End of story.

  6. #6

    Default fluid condition

    After I noticed the hydraulics were weak my online research led me to suspect a plugged strainer. When I cleaned that (and it was mostly plugged) I changed the fluid at that point. It had been changed when I bought the tractor but with ATF not 303 equivalent hydraulic oil but it looked fine. thanks for your response, Bill.

  7. #7

    Default filter change

    Actually changing the filter made it better for an afternoon's use but then it went back to the way it was. It appears that the tractor has not had the correct filter since it bought it. Bill

  8. #8
    Veteran Member
    Join Date
    Jul 2000
    Posts
    1,344
    Location
    West Virginia (Eastern Panhandle)
    Tractor
    '78 Kubota B6100DT

    Default Re: fluid condition

    How long was it run with the ATF in it?

    I'd say you can't do much more at this point until you get the right hydraulic fluid and right filter in it. You seem to indicate that the filter has come out with crud on it a couple of times since you've owned it so before you make that final change I'd suggest "flushing" it with a couple of fluid changes.

    When I got water in the hydraulic system of my kubota a year or so ago, the Kubota mechanic recommended I fill and drain it a couple of times with a 50/50 mix of diesel and hydraulic fluid to flush it out.

  9. #9

    Default Re: fluid condition - ATF

    I might be wrong on it being ATF but it was red and smelled like it. It was probably in less than ten hours. Bill

  10. #10
    Elite Member
    Join Date
    Mar 2002
    Posts
    3,451

    Default Re: filter change

    The problem sure sounds like dirty screen/filter. I would suspect a clean screen and correct fluid/filter would have, and will, fix it.

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