L555 new holland flow problem

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sandhills-elect

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My bother has a new holland L555 we have flushed the hydraulic system 2 times because when he bought it, it had water in the oil. We used john deere hydraulic oil. It has somewhere between 2000 to 3000 hours. Everything works good execpt when you go up and down large hills the the low oil light comes on and won't let you move the loader or the bucket execpt to go down, when you drop the bucket sometimes the light will go off and contiune to work other times you have to shut it of for a few minutes. Sometimes when you restart the pump seems to howl. The oil is right to the top of the full mark siting and not running. We checked the inlet screen many time and nothing. The filter were changed everytime we flushed. It works very well when you stay on level ground, but if you go up and down a hill it will act up. It will do it if you backup the hill or drive foward. Any ideas would be appreciated, Thanks in advace Brent!
 

skidsteer.ca

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Sounds like the charge pump is having trouble maintaining pressure in the hydrostat system.
When you drop the boom gravity turns your boom cylinders into temporary pumps and raises the pressure is my guess. You need to add a guage to the charge pressure system (look for where the sender is tied in for your light) Then its a matter of figuring if the pump is low on flow or if the oil is escaping somewhere it should'nt.
Does it work ok when pushing into a pile of gravel or does the extra power requied to move the machine into the pile make it act up then too?
If its only on a hill, could it be the the pickup for the charge pump is sucking air?
Just a few thoughts
Ken
 
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sandhills-elect

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Sounds like the charge pump is having trouble maintaining pressure in the hydrostat system.
When you drop the boom gravity turns your boom cylinders into temporary pumps and raises the pressure is my guess. You need to add a guage to the charge pressure system (look for where the sender is tied in for your light) Then its a matter of figuring if the pump is low on flow or if the oil is escaping somewhere it should'nt.
Does it work ok when pushing into a pile of gravel or does the extra power requied to move the machine into the pile make it act up then too?
If its only on a hill, could it be the the pickup for the charge pump is sucking air?
Just a few thoughts
Ken
Thanks Ken It only seem to happen on hills works fine when loading into a pile, it seem to do it when traveling up and down hill, we found this out because my borther bought this to use around his new house and of course it is built into the side of a hill and you go up top to the garage and main level and have a walk out basement. Working on the hill is where it acts up. I think that the charge pump many lose its oil and sucks air, but its full of oil and the level raises when you check it running, i though maybe we should put more oil in and see what happen, is this a good idea or not? I don't know how steep of a grade they are to operate on but this is not that seep of a grade. On those L555 the sucksion is elevated the lenght of the screen in the cross overtube from the chain cases. It is up about 6inches and if you remove the cover to inspect the screen and remove it, the oil is lower that the pickup tube, that is what is funny about how it works. I don't think it has been modified in anyway, looks to be factory so you think there would be a reason for it. I think the dipstick is factory, just a little confused on how it works. Thank for the help Brent.
 
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sandhills-elect

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Thanks Ken It only seem to happen on hills works fine when loading into a pile, it seem to do it when traveling up and down hill, we found this out because my borther bought this to use around his new house and of course it is built into the side of a hill and you go up top to the garage and main level and have a walk out basement. Working on the hill is where it acts up. I think that the charge pump many lose its oil and sucks air, but its full of oil and the level raises when you check it running, i though maybe we should put more oil in and see what happen, is this a good idea or not? I don't know how steep of a grade they are to operate on but this is not that seep of a grade. On those L555 the sucksion is elevated the lenght of the screen in the cross overtube from the chain cases. It is up about 6inches and if you remove the cover to inspect the screen and remove it, the oil is lower that the pickup tube, that is what is funny about how it works. I don't think it has been modified in anyway, looks to be factory so you think there would be a reason for it. I think the dipstick is factory, just a little confused on how it works. Thank for the help Brent.
Does anyone know the gpm on the charge pump? Thanks Brent.
 

Tazza

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Does anyone know the gpm on the charge pump? Thanks Brent.
The charge pump is the hydraulic pump. It uses pressure from it to act as a charge pump so you would be looking at a guess 12-16GMP minimum. It would take a pretty crook pump for it to not suply charge pressure and if your hydraulics work fast and are powerful i would suspect the pump is still good.
Charger is the man for this, he works on them for a living!
 

skidsteer.ca

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The charge pump is the hydraulic pump. It uses pressure from it to act as a charge pump so you would be looking at a guess 12-16GMP minimum. It would take a pretty crook pump for it to not suply charge pressure and if your hydraulics work fast and are powerful i would suspect the pump is still good.
Charger is the man for this, he works on them for a living!
I'd try overfilling the reservoir a a gallon, then maybe 2 (if you can squeeze it in) and see if the behavier improves or not.
Worst case you make a mess.
Ken
 
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sandhills-elect

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I'd try overfilling the reservoir a a gallon, then maybe 2 (if you can squeeze it in) and see if the behavier improves or not.
Worst case you make a mess.
Ken
Thanks everyone!! Added more oil and seems to have fixed the problem, i ran it about an 1hr today and i think the charge pump is a little weak though, i think we may install a new one for no more than they are, might save the trans pump. Thanks agian Brent.
 

Tazza

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Thanks everyone!! Added more oil and seems to have fixed the problem, i ran it about an 1hr today and i think the charge pump is a little weak though, i think we may install a new one for no more than they are, might save the trans pump. Thanks agian Brent.
I'd check with charger first, you may be throwing a new pump at the machine when it doesn't need it. It could be as simple as a poppet that controls the charge pressure.
 
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