B7100 double trouble with hydraulics, HELP

TxMidget

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Equipment
Kubota B7100
Jun 26, 2015
6
0
0
Whitesboro, TX
Im at my wits end on the tractor. Its a b7100d 1978 wilh a Kelly FEL. The steering went out 3 years ago and has just been sitting in the field. Decided to fix it and did ok with rebuilding the steering box. The control valve was pretty bad rusted but appeared to work. The hydraulics are running me crazy. The hydraulic pressure was showing 2000lbs with a gauge on the IN port of the control valve when either spool was activated. However when I pull the up lever it rolled the tilt at the same time or just barely lifted at all. This is an open circuit system so thought maybe was getting some cross flow in the valve. But I noticed after about 15 minutes of warming up ALL hydraulic pressure is lost. I have removed the screen filter 3 different times and flushed the system twice and it still does the same thing. I thought since the spool was rusty I might be bypassing pressure when spool was activated. I ordered a new hydraulic control valve and installed it, but it does the exact same thing. Rolling the tilt at the same time when the lift lever is activated and losing all pressure after 15 minutes. None of the lines have ever been changed except to switch them to the new control valve and I numbered them before removing and have checked for cross over several times. The pump is rated at 8 gpm and the valve is rated for 8 gpm. The new control valve is different from my old one as well. There is a hydraulic block on the high side of pressure pump. One line goes to IN port of controller, Out Port goes to the tank, and the Power beyond port goes back to the other side of the hyraulic block and continues to 3 pt hook up. If I put the little plug in the controller PBY as shown in directions the pumps squeals and shows 2000lb so apparently it blocks all pressure. Without the small plug inside it appears correct, but the bucket doesnt lift or roll correctly. Can any body help me figure this out. I have a new pump in the box, but havent installed it, as it doesnt seem like I should go from 2000lbs to 0lbs in 15minutes.

Original Old Valve with Power Beyond hooked up



B7100d hydraulic system. Line 5 was cut in the middle and a hydraulic block added with a line out to INPORT of controller valve and line return from POWERBEYOND. on control valve.


Hydraulic block






Loader hydraulic system.




New Prince Wolverine MB control valve. how is the High pressure plug and power out port suppose to be hooked up. When plug is in, it causes the pump to max pressure and go thru the relief valve. Uninstalled it appears to be open circuit, but both tilt and lift are activating at the same time when either spool is engaged.
 
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TxMidget

New member

Equipment
Kubota B7100
Jun 26, 2015
6
0
0
Whitesboro, TX
It works when the lifts on the FEL are working when they quit, it also quits. The gauge shows 2000lbs when lift is applies but it goes to 0 as well after about 15 minutes. I had to replace o rings on the 3pt piston to keep it from bleeding back down, recently.
 

ShaunBlake

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B6100D; B219; Piranha bar; Hodge stabilizers; Filled Ag rears; R322T w/48" deck
Dec 21, 2014
902
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80
Sugar Hill -- next door to Buford, GA
Sorry, I don't have hydro experience (yet); I want to follow your thread because I expect to need to utilize your lessons in the near future.

Why did you remove the filters so many times, and flush it twice? Just checking, or did you actually find crud?

Seems like a line is crossed (I know, you replaced the lines exactly the same way they originally were)... I wonder if the Prince control is actually different from the OEM control.

Soon some of the hydra (oops! I mean hydro <smirk>) heads will be chiming in, maybe tonight, certainly tomorrow.
 

North Idaho Wolfman

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L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
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Sandpoint, ID
If your using the pump that is on the back of the injector pump it's 3GPM not 8GPM, but that won't effect pressure just flow.

Disconnect the added hydraulics, so loop the in and out on the hydraulic block so that your only powering the 3 point, find out how that works, if you still have loss issues then either the pressure relief valve, or the pump is failing, lean towards the pressure relief valve.

On that set up you only need in and out of the valve.
from pump to in and from PB to three point cap the tank.
Make sure that the PB adapter is in it or the loader will raise and then will not go down.
If you have 2 lines swapped on the rams it will give you weird results. double check that each spool section only goes to one set of rams.
 

TxMidget

New member

Equipment
Kubota B7100
Jun 26, 2015
6
0
0
Whitesboro, TX
I did find crud on the filter screen the first time. The second time it looked ok and I checked it a third time. Just to be sure. I used fresh oil each time to be safe. The filter was a real pain to get in and out. The banjo fitting was about a quarter inch out of line. Had to take the tire off and make a spreader to get it back in, thought I might of messed up an o ring and maybe was sucking air, but don't see a leak and don't know if it would make a difference anyway.

I will try bypassing the control valve and use the 3 point only to see if that makes a difference. Don't know where the relief valve is for the 3pt, under the seat I would guess, and have never messed with it. Someone suggested that the controls could be getting some backflow thru the return line to the tank into the lift cylinders. Doesnt really sound logical.

I would think a pump would just gradually loose power, but not all the way from 2000 to 0. I put my gauge on the wrong side of the control valve originally and thought the pump was bad because I was getting a 0 reading and ordered a new pump. Its still in the box because I'm hoping I can return it. I've already invested more than the tractor is probably worth.

It I cap the return line to the tank, where does the relief pressure from the cylinders go? Downsteam via the PB outlet? That was the way it was set up when I bought it a long time ago and haven't changed it and tried to rig the new valve the exact same way. But it that will work I would be glad to do it, the return line is plugged into the fill hole and the hose is always in the way.
 
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North Idaho Wolfman

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L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
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Sandpoint, ID
Yes the "used" oil will be returned via PB.

Just a query, is the new valve an open center valve?
 

kubotasam

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Equipment
B2410, B7100dt, B7500,Woods BH750,Landpride 2660RFM, Tiller, B2781 Snowblower
Apr 26, 2010
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Alfred Maine
The documentation you posted talks of the "internal pressure carryover plug and a steel plug" being place in port C. Are you sure you are not confusing the two and accidently setting the valve to closed center?

Also you stated you think you might have damaged an O-ring on the suction tube/strainer. It will suck air causing the pump to cavitate. This might be the reason for the loss of pressure after a few minutes.
 

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TxMidget

New member

Equipment
Kubota B7100
Jun 26, 2015
6
0
0
Whitesboro, TX
I have tried it with the high pressure plug in and with it out. I have not tried it with the steel plug in, as I need the pressure downline to my 3pt. With the steel plug installed I have no way to return flow downstream I will be trying bypassing the control valve al together to see if the 3pt will stay working and at least see if I can eliminate it being or not being the pump.
 

TxMidget

New member

Equipment
Kubota B7100
Jun 26, 2015
6
0
0
Whitesboro, TX
Update: Tried disconnecting the return line and plugged it, result was hydraulics went up and would not come down, pressure jumped t0 3000 while holding control open ( I stopped pretty quick afraid was going to blow lines).
Bypassed the control valve to test 3pt and started having problems only to find that I had put on a new seat and it was compressing the lift lever, only when I was sitting on it. This appears to be the big problem with why the pressure was staying up with the high pressure plug in. Fixed that problem.
I removed all lines and flushed them and put the high pressure plug in and I switched the FEL lines from spool 1 and spool 2 and vice versa. Hydraulics appear to be trying to work properly. The tilt works properly whether on ports 1 and 2 or 3 and 4 with 2200lbs pressure. The lift has only 500lbs on lifts and 600lbs on pushing against the ground whether on spool 1 or 2. Haven't run it long enough to see if it still loses all power still.
I'm assuming I have at least 1 lift cylinder bypassing internally, I have not been able to locate and exact match for the seal kit, For 2inch hydraulic cylinder, part number shows to be scy1038 but haven't been able to locate one. I read somewhere that it calls for a hercules repair seal, if anyone can help me on that and how to test the cylinder it would be appreciated.