543 with slow lift/bucket action

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elbowcarey

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Feb 3, 2012
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Hey guys
This winter I am ready to tackle this project but need a little help. I know that I have slow operation up/down and curling/dumping but how do I prove what is the problem? Is this an obvious symptom of the pump or do I have to check the charge pressure? I would have to order or make something for this. Also can I buy replacement parts for the pump to rebuild it? I was looking for the pump and can only find one on loadersource.com and it doesn't seem to fit within my serial # so I'm not sure where to get parts for it. Also I already bought the reseal kit for the control valve so I plan on doing that and was wondering if I should also do the port block while everything is torn down. Any info would be great, I can do the work but I just need a little help on the right way to tackle this. Thanks Craig
 

OldMachinist

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The only for sure way to test the pump is to do a pressure and flow test but most people don't have access to the tester to do that so your next best thing is to check the hydraulic system pressure at the aux. connectors and see if adjusting the main relief valve helps. The 543 pressure should around 1500 psi at full throttle. The relief valve is adjusted by adding shims inside it to raise the pressure. Each .010" shim increases the pressure 100 psi.
 
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elbowcarey

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The only for sure way to test the pump is to do a pressure and flow test but most people don't have access to the tester to do that so your next best thing is to check the hydraulic system pressure at the aux. connectors and see if adjusting the main relief valve helps. The 543 pressure should around 1500 psi at full throttle. The relief valve is adjusted by adding shims inside it to raise the pressure. Each .010" shim increases the pressure 100 psi.
Thanks. What do you need to use to check the pressure at the Aux. Conectors? Also in the manual for this machine it says that you can adjust the pressure without removing the relief valve by turning the allen screw under the cap clockwise to increase and counterclockwise to decrease. In another section it mentions adding shims will increase pressure and not to exceed 4 shims (.040) I see what you mean about getting a reading at the aux. couplers so system pressure can be benchmarked before adjusting, but what do you adjust first and is it safe to assume that if adjustments to raise the pressure to 1500 are not successful that the pump is in need of replacement? Or is there rebuild kits avaliable? Thanks again
 

OldMachinist

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Thanks. What do you need to use to check the pressure at the Aux. Conectors? Also in the manual for this machine it says that you can adjust the pressure without removing the relief valve by turning the allen screw under the cap clockwise to increase and counterclockwise to decrease. In another section it mentions adding shims will increase pressure and not to exceed 4 shims (.040) I see what you mean about getting a reading at the aux. couplers so system pressure can be benchmarked before adjusting, but what do you adjust first and is it safe to assume that if adjustments to raise the pressure to 1500 are not successful that the pump is in need of replacement? Or is there rebuild kits avaliable? Thanks again
To check the pressure at the auxiliaries you can use a quick connect fitting or remove one of the quick connects to put a minimum 2000 psi gauge.
There were several different control valves depending on serial number.
The pump also depends on what serial number you have.
 
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elbowcarey

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To check the pressure at the auxiliaries you can use a quick connect fitting or remove one of the quick connects to put a minimum 2000 psi gauge.
There were several different control valves depending on serial number.
The pump also depends on what serial number you have.
Photo373.jpg

I checked pressure at the aux couplers at 1200 psi, manual says I am suppose to be approx. 1575 psi. The picture is the hose from the port block to the inlet side of the pump, its hard to see in the pics but it is sucked in, not round. I am going to replace it but is this a sign of a restriction somewhere prior to the pump causing this low pressure? The machine drives great, I need some help on what order to troubleshoot this problem any help would be great.
 
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elbowcarey

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I checked pressure at the aux couplers at 1200 psi, manual says I am suppose to be approx. 1575 psi. The picture is the hose from the port block to the inlet side of the pump, its hard to see in the pics but it is sucked in, not round. I am going to replace it but is this a sign of a restriction somewhere prior to the pump causing this low pressure? The machine drives great, I need some help on what order to troubleshoot this problem any help would be great.
Hey guys,
Well I replaced the bad hose on the inlet side of the pump and tried to adjust the relief valve but no dice, still 1200PSI. Next I'm gonna take the pump off and disassemble to see if there is any visible damage, I'll take some pics. Bobcat only carries a seal kit no rebuild kit so if its bad I'll have to buy the whole thing. Googled the # stamped on it 24206 RAT and found a new one for $390 @ Loader Parts Source (Eaton 26016LAL gear pump)
 

antfarmer2

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Oct 28, 2013
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Hey guys,
Well I replaced the bad hose on the inlet side of the pump and tried to adjust the relief valve but no dice, still 1200PSI. Next I'm gonna take the pump off and disassemble to see if there is any visible damage, I'll take some pics. Bobcat only carries a seal kit no rebuild kit so if its bad I'll have to buy the whole thing. Googled the # stamped on it 24206 RAT and found a new one for $390 @ Loader Parts Source (Eaton 26016LAL gear pump)
Did you make sure the aux is just not stuck on?
 
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elbowcarey

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Did you make sure the aux is just not stuck on?
I'm checking the pressure @ the lower aux coupler so when I move the right stick all the way to the right that's when it shows the 1200psi and when its moved to the left it goes back to zero. Or same thing if I put it in detent. When the machine is running with nothing being used and the gauge in the aux coupler it is at zero too. The machine does not creep and I would think with almost a 400psi loss that if another valve was partially open it would move slowly at full rpm? I was going to try to inspect the pump but yeah if anyone has a better idea I would appreciate it before replacing a $400 part
 

antfarmer2

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Oct 28, 2013
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I'm checking the pressure @ the lower aux coupler so when I move the right stick all the way to the right that's when it shows the 1200psi and when its moved to the left it goes back to zero. Or same thing if I put it in detent. When the machine is running with nothing being used and the gauge in the aux coupler it is at zero too. The machine does not creep and I would think with almost a 400psi loss that if another valve was partially open it would move slowly at full rpm? I was going to try to inspect the pump but yeah if anyone has a better idea I would appreciate it before replacing a $400 part
Did you check the upper aux as well?
 

jerry

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May 3, 2007
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No I did not check the upper. I will try it today. The hydraulic filter was changed. Appreciate the help
It would seem your problem is flow not pressure, have you ever resealed one of the cylinders and not recovered all the bits of the broken seals? Did you take the relief valves out and make sure there is no trash there or on the seat? If you have the old filter cut it open if you can to look for bits of things in there. You would think that with a empty bucket 1200 lbs should raise it almost as fast as 15 would. I do know of one bobcat that the tilt cyl seal has gone on twice and they have a lot of intermittent trouble from the bits of seal in the system.
 
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elbowcarey

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It would seem your problem is flow not pressure, have you ever resealed one of the cylinders and not recovered all the bits of the broken seals? Did you take the relief valves out and make sure there is no trash there or on the seat? If you have the old filter cut it open if you can to look for bits of things in there. You would think that with a empty bucket 1200 lbs should raise it almost as fast as 15 would. I do know of one bobcat that the tilt cyl seal has gone on twice and they have a lot of intermittent trouble from the bits of seal in the system.
I have not had to replace any seals since I bought it like 3 years ago but it is an older machine. I did replace the right-side drive because that side stopped working and one of the drive hoses but besides changing fluids and filters thats it. I did take the relief valve out but it looked clean to me so I put it back in. Is it suppose to be taken apart and cleaned or how do you know if it is working properly? And if the previous owner did reseal something and there are bits in the system how do you troubleshoot that? Remove all hoses and fluid?
 
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elbowcarey

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I have not had to replace any seals since I bought it like 3 years ago but it is an older machine. I did replace the right-side drive because that side stopped working and one of the drive hoses but besides changing fluids and filters thats it. I did take the relief valve out but it looked clean to me so I put it back in. Is it suppose to be taken apart and cleaned or how do you know if it is working properly? And if the previous owner did reseal something and there are bits in the system how do you troubleshoot that? Remove all hoses and fluid?
Removed the port block today and found a bunch of metal shavings in the oil-cooler bypass port and scarring on the inside of the fitting which was keeping the valve partially open. Inspected the rest of the ports and they are all clean. This Sucks!!!! Well since all the hydro fluid is drained out next I am going to the control valve. Do you guys have any thoughts on where these shavings would of come from? When I bought this machine I got it cheap because the right-side drive was bad and the guy didn't want to fix it. When I replaced it I didn't see any shavings however all I did was replace that drive could this be where these shavings came from? Thanks guys fo your help
 

antfarmer2

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Removed the port block today and found a bunch of metal shavings in the oil-cooler bypass port and scarring on the inside of the fitting which was keeping the valve partially open. Inspected the rest of the ports and they are all clean. This Sucks!!!! Well since all the hydro fluid is drained out next I am going to the control valve. Do you guys have any thoughts on where these shavings would of come from? When I bought this machine I got it cheap because the right-side drive was bad and the guy didn't want to fix it. When I replaced it I didn't see any shavings however all I did was replace that drive could this be where these shavings came from? Thanks guys fo your help
I would fix all you see and flush out the best you can and go from there
 
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elbowcarey

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I would fix all you see and flush out the best you can and go from there

Hey guys well I took the pump off and this is what it looks like..... A chipped tooth on the one gear and there's a few nicks in it and the other as well, the wear plate has circular pattern scratches in it, and the inside of the housing is scratched up real bad on both sides. I'm not sure what a brand new one would look like but I'm thinking not like this...
 

antfarmer2

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Oct 28, 2013
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Hey guys well I took the pump off and this is what it looks like..... A chipped tooth on the one gear and there's a few nicks in it and the other as well, the wear plate has circular pattern scratches in it, and the inside of the housing is scratched up real bad on both sides. I'm not sure what a brand new one would look like but I'm thinking not like this...
Tazza has used glass and wet and dry sandpaper I would look him up on the forum and email the info and pics to him he is the MAN
 

antfarmer2

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Oct 28, 2013
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Tazza has used glass and wet and dry sandpaper I would look him up on the forum and email the info and pics to him he is the MAN
Also call loadersourse they have more than what is on their website and can rebuild but would try Tazza first he is busy and a another time zone down under but has a wealth of wisdom
 

jerry

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Also call loadersourse they have more than what is on their website and can rebuild but would try Tazza first he is busy and a another time zone down under but has a wealth of wisdom
When I bought my 632 took the hyd filter off and it had collapsed internally, bobcat filter also. so then took the port block bronze filter out and it was full of metal wiry shavings. I cleaned out the port block as best I could and noticed that the wheel motors had been changed so that was probably the source of shavings. If your hyd charge pump is bad I think you are pretty much in for a new one, The wear plates in the hydro piston pumps can be resurfaced to a point but hyd pump is a different thing.
Despite all the crud in the 632 I never had anymore trouble after changing filters.
 

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