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Kubota KX91-3 lower boom will not extend

qphrfd01 ยท 2020-12-26 18:40

My 2004 Kubota KX91-3R1S 1,200 hrs. It was being used a couple days ago for about 4 hours when the lower boom stopped being able to extend out. With the R/H lever it moved up to the ROPS when the lever is pulled back but nothing when the lever is pushed forward. The thumb works with the switch on the R/H lever and the bucket tips back and forward when the R/H is activated side to side.

Replies13
  1. #1uffex2020-12-30 12:20

    Good day May I clarify is it that the boom will not raise - lower ? Kind regards Uffex

  2. #2qphrfd012020-12-30 18:34

    Hello, Thank you for your reply. The boom will not lower, the boom raises all the way back to the ROPS by using the right lever. On the right lever the bucket curls in and out and the thumb works. Since the post a dealer had me switch the 2 relief valves item # 250 on the parts diagram of the valve body. Also when I pulled back the boot on the right lever and exposed the pilot valve the port at 12 o/clock is free and can be compressed by finger. Also the cap screw on the upper right of the pilot valve is missing? and the level of fluid in the hydraulic tank is low just showing on the gauge. Thank you again

  3. #3uffex2020-12-31 05:13

    Good day If your machine has a pattern change valve please switch and see if the arm operates with the right side lever, this will tell us if the RCV (right side pilot valve) is working correctly. Kind regards Uffex

  4. #4uffex2020-12-31 05:21

    Looks something like the illustration

  5. #5qphrfd012020-12-31 17:36

    Hello and thank you again. I did switch the pattern and the left lever in the A position and did not reacted the same as the right lever. I guess we have eliminated the RCV as our problem? I really appreciate all your help. Thank you,Bill

  6. #6uffex2021-01-01 04:43

    Good day Bill As I have miss interpreted your response you have identified the problem as the RCV (Pilot control), our experience is that you can detect faults by response, it will feel different. The problem must be in the boom spool segment we will make an illustration for you in a short while. Not a good illustration but it is the best I have. Kind regards Uffex

  7. #7uffex2021-01-01 05:15

    Hi Bill The illustrated may not look identical but I guess it is fairly close. Kind regards uffex

  8. #8uffex2021-01-01 10:56

    Hi Bill I am a little concerned that we have not crossed wires so to say- the right side RCV will not lower the boom - when you switch to the left side (Pattern change) if you can lower the boom the right side RCV is bad if it is the same on the left side move on to check out the spool. Sorry if I have scrambled up the response. Kind regards Uffex

  9. #9qphrfd012021-01-01 15:36

    Good day After reading my response it seems confusing to me also, I will try to simplify. The lower boom will not operate down ( away from ROPS ) no matter what pattern I use. Thank you so much for your patience. Bill

  10. #10uffex2021-01-02 03:42

    Hi Bill Thats clear the RCV is fine check out the spool, if you are a little uncertain just follow the lines from the boom cylinders they must connect to the correct segment in the main valve chest, if you have any questions please come back. Kind regards Uffex

  11. #11qphrfd012021-01-02 09:45

    Hello OK sounds good, lets see what I find. Thank you for all your help. Bill

  12. #12uffex2021-01-02 13:42

    Hi Bill Just to be sure we have all the possibilities covered. KR Uffex

  13. #13qphrfd012021-01-02 17:50

    Hello I appreciate the tech sheet. It is suppose to snow all day tomorrow so it will be a good day to continue my trouble shooting in the shop. I will keep you informed Thanks, Bill