bobcat753 bucket wont move

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got a deal on this bobcat 753 diesel but the bucket wont move very much i think it could be the spools have 2 red wires are they seposed to be hot or just one i jump it and it click with one hot wire the plug has grean black coming from the harnes the bobcat has been working fine and quit now it just jumps a little like its still lock but you can drive it around and runs good when i move the cylinder i see only one hose jumping like its only flowing one way dont know i can turn the aux on and it jumps it had a seal leaking and a united rentel mechanic fix it and that went it quit working the leak was in the valve body thanx crackerwithcheez
 

Tazza

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The bucket as you mention, are you talking a 4 in 1 or is it a problem with lifting the arms?
With regards to HOT, do you mean that they have power going to them? or are they running hot?
Sorry for all the questions but just trying to figure out what the symptoms are.
As far as i'm aware, the spool body had 3 electric solenoids. One is to lock out all hydraulics for safety reasons till the BICS tells it to open. The other 2 are to control the aux hydraulics. Only one side should be energized at a time. These solenoids don't always run 12v so don't just hook them up to 12v without being sure as you may damage the coil. From what i know of these coils, the necks are very delicate and any small piece of rubbish in the system can cause them to stick.
The twitching hose does mean its getting pressure, its a good way to work out what hoses are under pressure.
 
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The bucket as you mention, are you talking a 4 in 1 or is it a problem with lifting the arms?
With regards to HOT, do you mean that they have power going to them? or are they running hot?
Sorry for all the questions but just trying to figure out what the symptoms are.
As far as i'm aware, the spool body had 3 electric solenoids. One is to lock out all hydraulics for safety reasons till the BICS tells it to open. The other 2 are to control the aux hydraulics. Only one side should be energized at a time. These solenoids don't always run 12v so don't just hook them up to 12v without being sure as you may damage the coil. From what i know of these coils, the necks are very delicate and any small piece of rubbish in the system can cause them to stick.
The twitching hose does mean its getting pressure, its a good way to work out what hoses are under pressure.
the lifting arm and tilt and when i said hot i ment 12v and what i did wuz plug the third one to it to see if it work and they do click becouse the bottom one is missing and that might be the problem and that might be the main one for the bics thanx tazza
 

Tazza

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the lifting arm and tilt and when i said hot i ment 12v and what i did wuz plug the third one to it to see if it work and they do click becouse the bottom one is missing and that might be the problem and that might be the main one for the bics thanx tazza
It could even be a stuck needle causing oil flow to your aux hydraulics. This will cause the problems you are describing too. If you have an attachment you can hock up to the quick couplers to see if its indeed flowing.
I'm only new to the newer machines, i'm still learning!
 
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It could even be a stuck needle causing oil flow to your aux hydraulics. This will cause the problems you are describing too. If you have an attachment you can hock up to the quick couplers to see if its indeed flowing.
I'm only new to the newer machines, i'm still learning!
i know that it flowing i took a line of a cylender and shot 30ft is the bottom spool have to be hook up? because its not
 
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i know that it flowing i took a line of a cylender and shot 30ft is the bottom spool have to be hook up? because its not
well i orderd the coil for it and i hope that does the trick as tazza said its part of the bics lock so that could be the problem soon to find out i will keep you all posted thanx
 

Tazza

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i know that it flowing i took a line of a cylender and shot 30ft is the bottom spool have to be hook up? because its not
Oil may still be flowing but depending on how its setup you may not be getting full pressure because the oil is going over the relief. There was a member in here with a late model machine and it had a problem with the aux hydraulics sticking. He setup a loop hose on the quick couplers and the lift and tilt worked as they should. Before every function was slow and very weak. He obviously got the solenoid problem fixed but the loop showed it was a stuck valve.
 
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Oil may still be flowing but depending on how its setup you may not be getting full pressure because the oil is going over the relief. There was a member in here with a late model machine and it had a problem with the aux hydraulics sticking. He setup a loop hose on the quick couplers and the lift and tilt worked as they should. Before every function was slow and very weak. He obviously got the solenoid problem fixed but the loop showed it was a stuck valve.
i have orderd the bisc control valve coil because it wuz missing wich its not unlocking it as for the aux hydrolics i will have to check it out after i get it on i think it working because i can feel it locking and unlocking when i hit the switch that dont mean nothing i will know when i get the coil thanx tazza
 
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i have orderd the bisc control valve coil because it wuz missing wich its not unlocking it as for the aux hydrolics i will have to check it out after i get it on i think it working because i can feel it locking and unlocking when i hit the switch that dont mean nothing i will know when i get the coil thanx tazza
well i put the new coil in but still nothing i took valve out and check them and they work fine could it be any thing else like a check valve or what does the anti cavity valve do help!!!! thanx
 

Tazza

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well i put the new coil in but still nothing i took valve out and check them and they work fine could it be any thing else like a check valve or what does the anti cavity valve do help!!!! thanx
I really don't know much about these newer machines but i'm going to learn in a hurry as i have a 751 i need to work on. The hydraulics as far as i'm aware are the same. I would still check that something is not causing oil to flow to your aux hydraulics, this will cause these exact symptoms. I don't think there is just one anti-cav valve that controls both lift and tilt, i think there is one on the tilt and not sure on the lift, but they were seperate as far as i was aware.
If you can, hook up an attachment to the quick couplers and see if oil is indeed flowing or not. If its not you know for sure its somewhere else.
 

sterlclan

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I really don't know much about these newer machines but i'm going to learn in a hurry as i have a 751 i need to work on. The hydraulics as far as i'm aware are the same. I would still check that something is not causing oil to flow to your aux hydraulics, this will cause these exact symptoms. I don't think there is just one anti-cav valve that controls both lift and tilt, i think there is one on the tilt and not sure on the lift, but they were seperate as far as i was aware.
If you can, hook up an attachment to the quick couplers and see if oil is indeed flowing or not. If its not you know for sure its somewhere else.
If nothing else try a short loop of hose between the aux couplers and see if it is any better
 
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If nothing else try a short loop of hose between the aux couplers and see if it is any better
i dont have attachments to hook up but i can make a loop and get a gage and check it but i know all the coils are working aux and bisc do i check the top and bottom of the aux or just one will do or i might need to rebuild the control valve dont know
 

Tazza

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i dont have attachments to hook up but i can make a loop and get a gage and check it but i know all the coils are working aux and bisc do i check the top and bottom of the aux or just one will do or i might need to rebuild the control valve dont know
You don't need to check them both if you make a loop, it will simply let the oil from one go to the other if that is the cause. If not, you can do one at a time with a pressure gauge and if you get 2,500 PSI on one you know its either a stuck needle or the aux hydraulic switch may be stuck or a wire shorting out.
 
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You don't need to check them both if you make a loop, it will simply let the oil from one go to the other if that is the cause. If not, you can do one at a time with a pressure gauge and if you get 2,500 PSI on one you know its either a stuck needle or the aux hydraulic switch may be stuck or a wire shorting out.
yea thats what i ment test each one with gage what would the kind of psi would i need to look for somewhere around 3500psi
 

scottyk

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Your machine should be between 2,500 and 3,000 PSI so if you go 3,500 you will be safe.
Hi, I had this same problem on my 753 machine and it took me three weeks to find the problem. I hope this helps. First connect the hose loop you made (to check flow) onto the aux couplers(just one side if you don't have a guage on the loop) Start the machine and check for flow. (If you don't have a guage and there is flow, oil will start shooting at start up so be ready to turn off engine immediately.) If you have flow on start up without turning on the auxillaries, then go to step two. If you don't then your problem is different from minds and you might want to examine the exact part or parts your mechanic touched on the control valve. Step Two. Look at your control valve and control valve schematics. Find the Aux spool that goes horizontally through the valve body, (not the vertical ones with solenoids on the top) My Aux spool was capped off with covers on either side of the control valve. If yours is the same as minds it will be the third spool counting from the bottom up. Take off the covers and see if the spool valve goes back and forth freely. Minds was stuck in the open position (sticking more towards the front of the machine) which is why I had flow on start up. If it is stuck, get it free, pull it out and clean it. It took a couple of taps with a hammer to free minds. Reinstall, make sure to put springs back in correctly and it should work. Hope this helps. If your not sure, give me a call at 808-645-6145.
 

scar99

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Dec 24, 2007
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Hi, I had this same problem on my 753 machine and it took me three weeks to find the problem. I hope this helps. First connect the hose loop you made (to check flow) onto the aux couplers(just one side if you don't have a guage on the loop) Start the machine and check for flow. (If you don't have a guage and there is flow, oil will start shooting at start up so be ready to turn off engine immediately.) If you have flow on start up without turning on the auxillaries, then go to step two. If you don't then your problem is different from minds and you might want to examine the exact part or parts your mechanic touched on the control valve. Step Two. Look at your control valve and control valve schematics. Find the Aux spool that goes horizontally through the valve body, (not the vertical ones with solenoids on the top) My Aux spool was capped off with covers on either side of the control valve. If yours is the same as minds it will be the third spool counting from the bottom up. Take off the covers and see if the spool valve goes back and forth freely. Minds was stuck in the open position (sticking more towards the front of the machine) which is why I had flow on start up. If it is stuck, get it free, pull it out and clean it. It took a couple of taps with a hammer to free minds. Reinstall, make sure to put springs back in correctly and it should work. Hope this helps. If your not sure, give me a call at 808-645-6145.
I am new to the site but I might be able to help. The red wire are for you auxillarys. They should not have power until the button on the panel is pushed and he trigger is pulled. The green and wire at the front of the valve is for the pedal locks. These would onle have power after the seat bar is lowered and the button is pushed. If those where bad you could remove them and run the machine with out them to test. They are a 1inch hex and just unscrew. There is 1 other stem in the center of the bics valve. This would unlock your lift and tilt functions. You said it was replaced. It sounds like you changed the pedal lock. Did you replace the solinoid or the stem. If you over tighten the nut on the stem it can damage the stem. Do you know if the machine is an F series or a G series. The F will have the BICS behind the seat and the G would be on the left dash panel. Make sure all of the lights are on after the button is pushed. The seat bar sensor or the seat sensor could cause all the same problems as above. Let me know if this helps.
 
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I am new to the site but I might be able to help. The red wire are for you auxillarys. They should not have power until the button on the panel is pushed and he trigger is pulled. The green and wire at the front of the valve is for the pedal locks. These would onle have power after the seat bar is lowered and the button is pushed. If those where bad you could remove them and run the machine with out them to test. They are a 1inch hex and just unscrew. There is 1 other stem in the center of the bics valve. This would unlock your lift and tilt functions. You said it was replaced. It sounds like you changed the pedal lock. Did you replace the solinoid or the stem. If you over tighten the nut on the stem it can damage the stem. Do you know if the machine is an F series or a G series. The F will have the BICS behind the seat and the G would be on the left dash panel. Make sure all of the lights are on after the button is pushed. The seat bar sensor or the seat sensor could cause all the same problems as above. Let me know if this helps.
what does the load check valve do its ajustable and do you think i should take the valve body off and check it and what should i check for
 

scar99

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Dec 24, 2007
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what does the load check valve do its ajustable and do you think i should take the valve body off and check it and what should i check for
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.
 
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