New Holland L555

[owens96]

I have an older New Holland L555. I recently replaced the pump that controls the right side of the machine. The machine worked fine for about an hour and then while tilting the bucket and lifting the arms the machine began to whine. The arms still raise, but much slower. I trammed the skid steer back up the road I was working on and when I turned it around I lost all hydraulics. The bucket would not lower and the wheels would turn the machine. The machine headed down the hill and I exited, because it was heading for disaster. Unfortunately the machine survived and since I have already invested so much money I thought I might try to fix the problem. Can anyone help me with this problem? Once we removed the skid steer from the bushes the wheels pulled, but the arms still whine and move slowly. While we were inspecting the machine the belt broke and the alternator was not turning. Any help would be appreciated.

 

[Tazza]

Do you know why the old pump failed and in what way? If it chewed up it's insides, you could have had metal in the system. With the new pump in, it could have moved it everywhere causing more damage. If a pump or motor fails badly, you really need to flush the system out before installing anything new.
Personally i'd start with pulling the hydraulic filter. Carefully cut it open as to not put shavings inside it. With it open look for metal particles. I use a large pipe cutter, but not everyone will have one of these.... It will give you a better idea of what has happened.

 

[Mike10]

Tazza has it right. If you had a pump failure and did not flush the entire system or remove the hydro motor and at least check it for damage you proabaly have a lot of metal circulating through the sytem. The standpipe screen where the hydraulic pump draws it's oil may be completely plugged causing the hydraulic pump to squall as it tries to pull oil into it. While the screen does a good job of keeping metal out of the hydraulic pump, it is still possible that some got through to the control valve relief valve partially sticking it open which would cause the hydraulics to operate slow and squall.
If the screen is full of metal, then the first thing I would do is remove both hydro pumps and check them both for further damage. I would then pull the hydro motors and check them for damage. You need to determine how much damage you have before you decide whether to fix it or not.
Flushing the system is a time consuming job since everything in touch with the hydraulic oil needs to be cleaned. The oil cooler should be replaced because you can not get all the metal out of it. You are looking at chain cases, hydraulic cylinders, all hydraulic lines, control valve, hydrualic pump, axles, etc.

 

[owens96]

Tazza has it right. If you had a pump failure and did not flush the entire system or remove the hydro motor and at least check it for damage you proabaly have a lot of metal circulating through the sytem. The standpipe screen where the hydraulic pump draws it's oil may be completely plugged causing the hydraulic pump to squall as it tries to pull oil into it. While the screen does a good job of keeping metal out of the hydraulic pump, it is still possible that some got through to the control valve relief valve partially sticking it open which would cause the hydraulics to operate slow and squall.
If the screen is full of metal, then the first thing I would do is remove both hydro pumps and check them both for further damage. I would then pull the hydro motors and check them for damage. You need to determine how much damage you have before you decide whether to fix it or not.
Flushing the system is a time consuming job since everything in touch with the hydraulic oil needs to be cleaned. The oil cooler should be replaced because you can not get all the metal out of it. You are looking at chain cases, hydraulic cylinders, all hydraulic lines, control valve, hydrualic pump, axles, etc.

When we changed the pump we drained all of the hydraulic oil from the system and looked for metal. The chain cases have large magnets and we looked for metal there, because everyone told me we needed to be sure to remove all of the metal. I replaced the hydraulic oil and ran the machine for a little bit and replaced the filters and drained the oil. We repeated this twice. I don't know if that is sufficient to clean the system of metal shavings. I will look in the screen and filters to see if I can find any metal. Thank you guys for taking the time to help me out.

 

[Mike10]

When we changed the pump we drained all of the hydraulic oil from the system and looked for metal. The chain cases have large magnets and we looked for metal there, because everyone told me we needed to be sure to remove all of the metal. I replaced the hydraulic oil and ran the machine for a little bit and replaced the filters and drained the oil. We repeated this twice. I don't know if that is sufficient to clean the system of metal shavings. I will look in the screen and filters to see if I can find any metal. Thank you guys for taking the time to help me out.

Unless you removed the hydro pumps and motors, and disassemble them,when you have a hydro pump failure the grit remains in the hydro system since it is more or less a closed system with the only new oil added as leakage occurs in the system. What type of failure did you have? Be sure to check the standpipe screen.

 

[owens96]

Unless you removed the hydro pumps and motors, and disassemble them,when you have a hydro pump failure the grit remains in the hydro system since it is more or less a closed system with the only new oil added as leakage occurs in the system. What type of failure did you have? Be sure to check the standpipe screen.

I apologize for taking so long to post. I haven't had much time to work on the skid steer. After reading the advice, I took the standpipe screen out and it was completely stopped up. After cleaning the filter, the machine returned to normal. Thank you for your help. I hope that the skid steer continues to operate properly.