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DDG
DDG, Service Coordinator
Category: Heavy Equipment
Satisfied Customers: 104
Experience:  2 years Truck shop experience, 12 years of Bobcat Compact Equipment experience
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Bobcat: the hydraulic system doesnt work..10 minutes..hydraulic pump

Customer Question

hi I have a bobcat s250 that the hydraulic system doesn't work when it's been seating a couple hours, after 10 minutes of being tryng then it start working fine, what else should I try, I had somebody to rebuit the hydraulic pump,
Submitted: 3 years ago.
Category: Heavy Equipment
Expert:  daves71 replied 3 years ago.

HiCustomer does the machine travel fine but the arms don't raise and lower, or does the machine not work untill it has warmed up at all? Let me know and we can go from there,thanks,

Dave

Customer: replied 3 years ago.

the machine works fine but the arms don't raise or does it real slow and when it raises won't go down and bucket doesn't change angle either, until I have been playing with the pedals for like 15 minutes

Expert:  DDG replied 3 years ago.

Are all of the BICS lights, such as seat bar, traction lock, and Lift/Tilt illuminated on the left hand panel?

 

You may want to inspect the BICS solenoid valve stem on the control valve to be sure the valve stem is not stuck or sticking closed.

 

Follow all Safety and Maintenance Procedures as illustrated in the Operation and Maintenance Manuals for your machine! Remember to click ACCEPT.

Customer: replied 3 years ago.
what is the bics solenoid, how should i inspect it, could i get a pic or diagram
Expert:  DDG replied 3 years ago.
This system does not have a way for me to give photos or diagrams. The BICS solenoid is the lone solenoid valve that has wires 2410 and 4410 connected to it.
Customer: replied 3 years ago.

where is located this solenoid, if I remove the solenoid what should i do? or how I test it, if you could send me a website where i could get the info that I need, or email me diagrams

Expert:  DDG replied 3 years ago.

The solenoid is on the main hydraulic control valve on the right side of the inside of the machine, under the cab.

 

I believe the solenoid itself is ok since you did not say there are fault codes beeping at you. Is this true?

 

I think the solenoid valve stem may not be opening when it should, to activate the hydraulics fully.

 

Is this machine equipped with ACS or SJC controls? If so, there could be a calibration problem with them as well. Your local dealer would have to test/calibrate the controls to troubleshoot that type of a problem.

Customer: replied 3 years ago.

there are no codes, what's acs or sjc controls.

 

what is the function of the electrical part of the solenoid, foot linkage should open and close valve manually, don't you think it would be related to hydraulic pump,

 

Expert:  DDG replied 3 years ago.

ACS is Advanced Control System, that lets you switch between hand and foot control of the lift and tilt. SJC is Selective Joystick Controls, that is hand controls only for drive, and lift/tilt, but lets you select between H pattern or ISO pattern controls.

 

If a pump is failing, it fails and stays that way. It does not act up a little here, then work correctly for a while.

 

The BICS solenoid is what activates the BICS (Bobcat Interlock Control System) which is what prevents the lift and tilt from moving when the seat bar is raised, or the cab door is open, etc. The BICS system locks the lift and tilt using PD10 lock valve cartridges on the main control valve. The solenoid provides pilot pressure (charge pressure from the hydrostatic pump) to unlock the PD10 lock valves to allow the lift and tilt to operate when you enable the system.

 

You said the boom will raise slowly, and will not come down and the tilt will not move. This sounds a lot like the BICS system not fully activating.

 

If you are not comfortable, or familiar with the system, the best advice I can give is to have your local dealer take a look at the problem.

Customer: replied 3 years ago.

is the any sensor that checks if the seat bar is in the right position or the cab, is that what I should refer to?

 

do you think that just the electrical part of the solenoid is preventing from operating the control valve?

 

is this solenoid mounted on the valve that the foot linkage goes to?

if a remove the solenoid is there any special care that I shoud take when removing this valve?

Expert:  DDG replied 3 years ago.

I do not think the problem is electrical since there are not any fault code occurring. The controller monitors the electrical portion of the systems and can detect faults with it.

 

Yes the stem is on the hydraulic control valve that the pedal linkages are attached to.

 

When removing the stem for inspection, follow all safety precautions as illustrated in your Operation and Maintenance Manual. Keep the boom down if possible, and if it must be raised while working on the machine, the boom support devise absolutely MUST be installed to support the boom from falling and causing injury.

 

I would inspect the BICS valve stem, and the two cartridge valves located next to it. Inspect for debris holding them, or for their plungers to be sticky instead of moving smoothly. You can press on the plungers with a small tool to feel their operation.

Customer: replied 3 years ago.
is there a diagram that I can get to disassemble the control valve, or a special tool? because the two cartrigde seem to be clean and the plungers from the control valve don't come off, one of them moves a little bit smoother that the other one they move in and out feels that they have a spring loaded when pushed or pulled.
is there another thing that i should check?
Customer: replied 3 years ago.
the attanchements don't work (hydraulic hammer), it is supposed to work when I push the
maximun flow button and there aren't any pressure on the lines when a try to operate.
Expert:  DDG replied 3 years ago.

Are there any active fault codes right now?

 

The aux flow is controlled by two more solenoids on the control valve. One at the top rear, and one at the top front. Were they possibly disconnected from when you were doing other work on the control valve. Check their connections?

 

Not trying to insult you with this question, just trying to rule out the simple stuff. Is the Max flow light on the panel illuminated, and did you press the trigger on the right handle?

 

Do you hear aux pressure load when moving the thumb switch on the right handle?

Customer: replied 3 years ago.
there are no codes at this right now, and I dont recall the front top solenoid, but for sure there is no disconnected solenoids, on the inside botton there is a solenoid that looks to have I jumped wires to itself.

the max flow and another opcion and the same button that i cant recall the name, it's lights are working fine when i push the buttons on and off, there is a button only on
the left of max flow that the light doesn't work, but i never used that button before.

I cant hear or feel aux pressure at all when a push any button on top or handle.
thanks for attending me again, didn't mean to wait too long, but I don't have my bobcat
close to me.
Expert:  DDG replied 3 years ago.
I assume that you were trying to operate the aux with the breaker hoses connected, right? The problem could be that the oil is leaking straight though the breaker. Disconnect the breaker hose couplers from the loader and try the aux that way. Do you hear the pressure deadhead with the hoses disconnected?
Customer: replied 3 years ago.
yes the hoses were connected from the hydraulic hammer to bobcat, but it doesn't feel any pressure when i disconnect the hoses and try to operate.
Expert:  DDG replied 3 years ago.
If you were using just the trigger, try the thumb toggle both directions. If nothing happens either direction, I suspect that the main control valve aux spool is stuck and not shifting to engage the auxiliary hydraulics.
Customer: replied 3 years ago.
yes I have tried all possible, buttons.

is this on the main control valve, and do you think is related to the problem when the arms doesn't move when is started after several hours,

Last night I noticed that the problem went away when accidentally pushed the release pressure button and I started up again, it worked fine even that was doing it just before i pushed the button and had been seating the whole day.

Of couse the aux pressure didn't make any difference.
Expert:  DDG replied 3 years ago.

Yes it is in the main control valve. The control valve has three main spools. Lift, tilt, and auxiliary.

 

If the aux spool ever sticks out of neutral for any reason, with no attachment connected, it could cause the lift and tilt to not work correctly. Usually it will cause the lift and tilt cylinders to not want to retract (boom down, bucket roll back). They would still extend (boom raise, bucket dump) but maybe a little slower than usual.

Customer: replied 3 years ago.
just before a spend the big bucks, is there other thing that you think i should check, or test, like electrical issue, the solenoid resistance or remove them and operate them applying power to them or like you said the codes should take care of that if it was electrical.


If I need to replace the control valve, what would you recommend, having it rebuilt or new let's say to save a few bucks,

after replacing valve, should I purge the hydraulic system (if apply) or there is a special way to do it, or just fill the reservoir?
Expert:  DDG replied 3 years ago.

Fault codes would indicate an electrical fault with the aux control system.

 

If the aux spool is hanging up, it is likely to have scored the bore in the valve body and will require a complete new valve. A new valve is cost competitive with the labor and parts for rebuilding it anyway. New is the way to go.

 

After the new valve is in place, fill the reservoir to full, start the machine and run at low idle, and slowly cycle all functions several times, slowly, and with no load, to purge air in to the reservoir. Keep an eye on the oil level and add as necessary to keep it at the acceptable level.

DDG, Service Coordinator
Category: Heavy Equipment
Satisfied Customers: 104
Experience: 2 years Truck shop experience, 12 years of Bobcat Compact Equipment experience
DDG and 4 other Heavy Equipment Specialists are ready to help you
Customer: replied 3 years ago.
I removed the valve and took it to dealer to have it rebuild, got it back after a couple of weeks, the bucket move perfectly, it worked for that part, but the the hydraulic hammer still don't work, the hammer has been working with another bobcat that makes me think that is not the hammer.

what else should i check, I am an ase certified electrical, but no expertise on this, so just guide me, i will doit.

Customer: replied 3 years ago.
I removed the valve and took it to dealer to have it rebuild, got it back after a couple of weeks, the bucket move perfectly, it worked for that part, but the the hydraulic hammer still don't work, the hammer has been working with another bobcat that makes me think that is not the hammer.

what else should i check, I am an ase certified electrical, but no expertise on this, so just guide me, i will doit.
Customer: replied 3 years ago.

I reveived an email message that I have free follow ups, it that true?

I didn't mean to finish the question but i pushed on the wrong button

 

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