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490 E Hydraulic problem -Help Please

Discussion in 'Excavators' started by badinf, Oct 4, 2009.

  1. badinf

    badinf Member

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    Location:
    Kansas
    I have a 490 E John Deere which is built by Hitachi, it has around 5200 Hrs. on it. I recently rebuilt the main hydraulic pump with the following new parts - cylinder, pistons, driveshaft, spring, servo piston, and valve plate.

    After getting it together and the air out of the lines evrything was working as it should. I went to work it for the 1st time and after 10 minutes the hydraulics would just shut off. I would shut the machine off and restart it and have hydraulics for just a few seconds then stop working.

    The engine does not pull down or change the way it is running. It seems to be more of an electrical problem.

    When I re-assembled the head I was careful to make sure the valve plate pin was in the angle sensor arm. Is it possible I didnt get it in properly? Or did this need adjusted after rebuilding the pump? I am at a loss and hoping someone on here has an answer. Thanks in advance for any help.
     
  2. -3Doc

    -3Doc Well-Known Member

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    Have you checked the wiring going to the pump displacement solenoids on the pump? When you hooked it back up you may have got the wires switched, you can try and switch them and see what happens, It will not hurt anything. Also check that all fuses are good in the fuse box. Two fuses are for solenoids and two for computers. If none of this works let me know and I will send you the procedure for setting up the angle sensor. It does sound like an electrical problem to me. When you shut the machine off it will restart in full swash and will slowly cut back to zero swash if it gets no electrical signal to the solenoids.:canada
     
  3. -3Doc

    -3Doc Well-Known Member

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    Here are the instructions for setting the angle sensor. In installation Item #2 it should read make sure the punch mark on the shaft and the wiring harness face you when installing onto side of pump. I have seen some new angle sensors with the label stuck on the wrong side and that will screw you up!!:canada
     

    Attached Files:

  4. POWERENG

    POWERENG New Member

    Joined:
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    Location:
    egypt
    thanks so much
    but can you tell me how to adjust the ( tvc ) fro the proper swash plate angle suited with the engine .....

    thannks
     
  5. badinf

    badinf Member

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    -3 Doc, thanks for the response, when i did the rebuild I didnt pull the whole unit so the pump displacement solenoids were not disconnected, so we can rule that out. I didnt pull the angle sensor either. When I put the head on, I just tried to make sure the swash plate dowel was in the angle sensor arm.

    Doc- do you think the angle sensor needs adjusted or could I have messed up the angle sensor?

    Thanks again.
     
  6. -3Doc

    -3Doc Well-Known Member

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    :)
    I would pull the angle sensor out and stick a screwdriver into the slot that it is in and easily try to turn the shaft, if it turns then you have missed the slot with the pin. That is a good place to start.:)
     
  7. -3Doc

    -3Doc Well-Known Member

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    Not sure what you are asking for?? TVC??:confused:
     
  8. badinf

    badinf Member

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    Seems tobe fixed

    -3 Doc, I pulled the angle sensor and checked it, It was engaged properly, I was noticing a pulsing noise coming from the valve body. I kept messing with the machine and got the controls to stay working, I took it out to the pasture and worked the machine for an hour or so and the pulsing noise quite and controls all worked properly.
    Is it possible I had air still in the system and a sensor not seeing pressure and shutting down the controls ? All seems to be working properly now.
    Thanks for helping me out I do appreciate it.
     
  9. -3Doc

    -3Doc Well-Known Member

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    Anythings possible!! As long as it is working good now that is all that matters, glad I could help!:)
     
  10. Andre-1

    Andre-1 Active Member

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    Must there be a pulsing 24 volts at the pump displacement solenoids or does the voltage vary? (490e deere excavator)
     
  11. -3Doc

    -3Doc Well-Known Member

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    The computer controls the ground wire from each of these solenoids and turns them on and off as oil flow is needed or not. It is not a regular pulse but on and off as the computer monitors pressure and engine rpm.
     
  12. Andre-1

    Andre-1 Active Member

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    Thanks 3Doc. I monitored the voltage across each solenoid with my multimeter and got varying voltages; 6v,8v and 13volts. This must mean i have a bad harness.
     
  13. shopguy

    shopguy Senior Member

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    help me out here 3doc dosent he need to
    check across term.1 (with the lockclip turned up it is the wire on the left)of solenoid harness and ground for 24 volts
     
  14. Andre-1

    Andre-1 Active Member

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    yes shopguy I did that and i got 24 volt with the key switch on when checkin between the harness and ground. i tried monitoring the voltage while the machine is running to see whether the solenoids are being turned on and off by checking the voltage across the solenoid but I dnt get 24 volts. Today I checked it and got 2 volts max. must it be 24 volts going to the solenoids when they open?
     
  15. shopguy

    shopguy Senior Member

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    ok,the 24 volts on that wire is constant the ground comes from the pvc (no 2 wire)as needed that is the pulse it is very very quick. use a test light and you should see short flash.also (with key off) unplug solenoids check ohms on them both
     
  16. Andre-1

    Andre-1 Active Member

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    When testing for 4.4Volts at the Angle sensor which two wires should i probe. the instruction above just says connect to harness.I need to know which wires specifically because there are three wires on the connector. Ground, signal, reference. Please help.
     
  17. jey_c

    jey_c Senior Member

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    Between signal and ground.
     
  18. Andre-1

    Andre-1 Active Member

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    Thanks jey_c, I adjusted it today with the punch mark away from the harness side and made adjustments unitl i got 4.4 volts between signal and ground. The machine no longer stalls when i fully extend or retract any cylinder. My problem now is that when booming up and simultaneously pulling the arm in, the arm comes in very slowly and with this motion continuosly repeated there comes a point when the arm will pause for like 3 seconds then sudden jolt and it continues moving in. I tested the arm in pressure switch while operating the arm in function from the joystick but the switch doesnt close. neither does the swing pressure switch. swinging and booming up causes the swing to slow down. the only two pressure swithes that close whenever its corresponding function is operated is the boom raise switch and the arm out, boom down bucket pressure switch. I checked the wires using my multimeter from the connector end to the end that goes to the pvc and i have continuity with no shorts. What could be preventing the other switches to close when they should . I read that this could cause the symptom the machine has, which is slow combined operations. you can actually feel the pressure dropping in the joystick for the arm when your moving more than one functions.
     
  19. rgl726

    rgl726 Well-Known Member

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    cebu city, philippines
    if thats the case check your pilot pump pssure. at least it should be 700 psi with a very little pressure flactuation when you are giving pilot command.

    the pump pressure i deceiving you mush monitor it when giving pilot command.

    weak pilot pump would result to poor combined operation
     
    Last edited: Sep 12, 2011
  20. Andre-1

    Andre-1 Active Member

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    Thanks ,gonna do that