bobcat753 bucket wont move

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OP
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The load check is not adjustable. When you move the pedal to raise the arms it keeps the arms from dropping slightly before they go up.
well all i have is parts book so i am going to order the service parts book and that should help me!!!! thanx
 

Tazza

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well all i have is parts book so i am going to order the service parts book and that should help me!!!! thanx
I hope it sheds a bit more light on the problem..... Have you tried your local dealer? they may have some ideas too.
Now, i do suspect all the lights are lit on your BICS box? just wondering if its locking you out for some reason....
 
OP
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I hope it sheds a bit more light on the problem..... Have you tried your local dealer? they may have some ideas too.
Now, i do suspect all the lights are lit on your BICS box? just wondering if its locking you out for some reason....
yes all lights are on and i can drive it and the bucket just barley moves let me ask you something tazza lets say my set screw on my main relief valve back out some on its on could it cause the same problems?
 

skidsteer.ca

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yes all lights are on and i can drive it and the bucket just barley moves let me ask you something tazza lets say my set screw on my main relief valve back out some on its on could it cause the same problems?
If your relief valve set screw backed off or the relief had a broken spring, the pressure would drop and the hydraulics would be lazy as you describe. It's hard to imagine it getting so bad it won't move the empty loader arms. That would be under 500 psi imo.
Hooking a pressure guage into the front couplers would confirm if there is a lack of pressure (generally 2250 to 3000 psi) A worn out pump would act the same but get worse as the oil warms up.
If you idle the engine and move the foot pedals does the engine labour at all? like its trying to do some work. If you have no pressure the engines tone/sound should not change.
Ken
 

Tazza

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yes all lights are on and i can drive it and the bucket just barley moves let me ask you something tazza lets say my set screw on my main relief valve back out some on its on could it cause the same problems?
Theoretically it could *if* the poppet or spring were stuck it could allow oil to be by-passing giving you little or no pressure. Small adjustments of the relief pressure will do nothing to cause problems like this. All it will do is increase or decrease your main hydraulic pressure by a small amount, it would not normally cause you to loose essentially all hydraulic pressure to your hydraulics.
Did you find out if some how your aux hydraulics were coming on at all? You were looking at installing a pressure gauge, did you ever get to doing it?
As you have been tinkering with your main relief valve, you may want to remove it to check there isn't a part of an old o-ring stuck under the poppet. A relief valve problem would explain slow/weak hydraulics.
 
OP
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Theoretically it could *if* the poppet or spring were stuck it could allow oil to be by-passing giving you little or no pressure. Small adjustments of the relief pressure will do nothing to cause problems like this. All it will do is increase or decrease your main hydraulic pressure by a small amount, it would not normally cause you to loose essentially all hydraulic pressure to your hydraulics.
Did you find out if some how your aux hydraulics were coming on at all? You were looking at installing a pressure gauge, did you ever get to doing it?
As you have been tinkering with your main relief valve, you may want to remove it to check there isn't a part of an old o-ring stuck under the poppet. A relief valve problem would explain slow/weak hydraulics.
well i got i wild hair today and removed the valve body and took it completely apart and cleaned very good found a piece of a o ring and put it all back together and the tilt on the bucket went all the way down but still moving just a little bit one thing i did notice is that the spools had a little bit of scaring on the lift and on the tilt could that be my problem!!!! it took me about 10 hrs to do if its not the spools then it has to be the manual relief valve maybe or my main relief valve i am going to try to tighten it up tomorrow and check the manual relief i still got to go get me a pressure gauge and check it and make me a loop hose thanks for all the help and support
 

Fishfiles

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well i got i wild hair today and removed the valve body and took it completely apart and cleaned very good found a piece of a o ring and put it all back together and the tilt on the bucket went all the way down but still moving just a little bit one thing i did notice is that the spools had a little bit of scaring on the lift and on the tilt could that be my problem!!!! it took me about 10 hrs to do if its not the spools then it has to be the manual relief valve maybe or my main relief valve i am going to try to tighten it up tomorrow and check the manual relief i still got to go get me a pressure gauge and check it and make me a loop hose thanks for all the help and support
Does your tilt cylinder have a resistor valve on the down side of the cylinder , it is a fitting that is screwed onto the 90 degree fitting coming off the down side the cylinder , not all machines have these , they were put on to slow down the down stroke with a heavy attachmnet to prevent damage to the tilt cylinder , like a bent rod , the plastic orrifice inside of it breaks up and plugs up the flow , also if no other functions are affected I would look in the tilt cylinder , the nut or bolt depending on set up could have come off or loosened up
 
OP
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Does your tilt cylinder have a resistor valve on the down side of the cylinder , it is a fitting that is screwed onto the 90 degree fitting coming off the down side the cylinder , not all machines have these , they were put on to slow down the down stroke with a heavy attachmnet to prevent damage to the tilt cylinder , like a bent rod , the plastic orrifice inside of it breaks up and plugs up the flow , also if no other functions are affected I would look in the tilt cylinder , the nut or bolt depending on set up could have come off or loosened up
yes all the cylinders do have the allen head screw i will check it today thanx
 
OP
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yes all the cylinders do have the allen head screw i will check it today thanx
I got a gage on the quick couplers and my gage is only showing about 100 psi so i ajusted the main relief valve and still the same the only thing is that the moter bogs down does anybody know what can i check next or do i need to take the pump off and rebuild it thanx
 
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I got a gage on the quick couplers and my gage is only showing about 100 psi so i ajusted the main relief valve and still the same the only thing is that the moter bogs down does anybody know what can i check next or do i need to take the pump off and rebuild it thanx
well i took one of the couplers off and left one on and the gage went up to 3800 ---- well i need to turn it back down does anybody know what else to check out my bucket still don't work could it be a cylinders leaking all my fluid back
 

Tazza

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well i took one of the couplers off and left one on and the gage went up to 3800 ---- well i need to turn it back down does anybody know what else to check out my bucket still don't work could it be a cylinders leaking all my fluid back
No way you could have that much oil by-passing causing your arms to not move. I will re-read the thread and see if i can think of something... Its almost like your lift arm lockout isn't allowing you do operate it but i didn't think it would make the machine bog down, but i am new to later model machines.
 

Tazza

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No way you could have that much oil by-passing causing your arms to not move. I will re-read the thread and see if i can think of something... Its almost like your lift arm lockout isn't allowing you do operate it but i didn't think it would make the machine bog down, but i am new to later model machines.
The 100PSI i assume is when you just plug into the quick couplers without activating the aux hydraulics. When you activate the aux. thats when it should jump. Did you try both connectors? as oil will run from one to the other.
I re-read the thread, i can't think of anything else.... It still sounds like you have an electric solenoid that is sticking..... Have you contacted your local dealer at all?
 

scottyk

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The 100PSI i assume is when you just plug into the quick couplers without activating the aux hydraulics. When you activate the aux. thats when it should jump. Did you try both connectors? as oil will run from one to the other.
I re-read the thread, i can't think of anything else.... It still sounds like you have an electric solenoid that is sticking..... Have you contacted your local dealer at all?
Give me a call I went crazy with my bobcat for a while but found the problem. I had the same problem. 808-645-6145 Scott
 
OP
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Give me a call I went crazy with my bobcat for a while but found the problem. I had the same problem. 808-645-6145 Scott
ok got the main relief valve set but i took the lines of my tilt cylender and hook the gage up and i ownley have down pressure and not up what would cause this my aux hydraulics work fine
 

Tazza

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ok got the main relief valve set but i took the lines of my tilt cylender and hook the gage up and i ownley have down pressure and not up what would cause this my aux hydraulics work fine
I have been told a 753 is essentially the same as a 751 which i am currently working on. It has a small block plumbed to the main control block by 2 hoses. It has a small handle attached to it that as far as i understand is used to release hydraulic pressure when working on the arms. Could it be as simple as this being stuck open causing your oil to leak back to the tank?
Just a thought....
 
OP
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I have been told a 753 is essentially the same as a 751 which i am currently working on. It has a small block plumbed to the main control block by 2 hoses. It has a small handle attached to it that as far as i understand is used to release hydraulic pressure when working on the arms. Could it be as simple as this being stuck open causing your oil to leak back to the tank?
Just a thought....
yea i thought of blocking that line and see if it works but i think its my port relief valve maybe cant tale if its broke or not looks like it is could that do it i need to go by bobcat dealer and look at a new one the one i have the center peice is sunk in like maybe a piece of it broke off or not working
 
OP
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yea i thought of blocking that line and see if it works but i think its my port relief valve maybe cant tale if its broke or not looks like it is could that do it i need to go by bobcat dealer and look at a new one the one i have the center peice is sunk in like maybe a piece of it broke off or not working
i took it apart and it all looks good and sealed anything else please help what would cause this???????
 

Tazza

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i took it apart and it all looks good and sealed anything else please help what would cause this???????
I really can't think of anything else....
Can you take a pictures of the control block at all? I keep thinking it has to be something to do with your BICS locking the lift arms out.... I just keep thinking of that lockout solenoid. I remember you saying you could feel and hear it click as it was energized. It has to be in that area. Even if the block that removes the pressure from the lift arms was open, it only has 1/4" feel lines to it, if it was stuck open your arms would still lift, but have reduced speed and power. It however does not effect the tilt of your bucket.
Have you harassed your local dealer? you can try talking to the service department and see what they have to say.
 

perry

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I really can't think of anything else....
Can you take a pictures of the control block at all? I keep thinking it has to be something to do with your BICS locking the lift arms out.... I just keep thinking of that lockout solenoid. I remember you saying you could feel and hear it click as it was energized. It has to be in that area. Even if the block that removes the pressure from the lift arms was open, it only has 1/4" feel lines to it, if it was stuck open your arms would still lift, but have reduced speed and power. It however does not effect the tilt of your bucket.
Have you harassed your local dealer? you can try talking to the service department and see what they have to say.
I don't know if this helps but, what about the switch on the safety bar?.
 
OP
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I don't know if this helps but, what about the switch on the safety bar?.
yea everything is working that i know or all my lights would not come on some reason i am not building fluid up on my lift sides of the bisc block i getting down pressure and my aux works fine and i am going to call the dealer Monday but he want me to bring it to him i am going to check around at a different one
 

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