LX 665 Boom Hydraulic Problems

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dbolt

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Feb 26, 2008
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1999 LX 665, has intermittent times when the boom will: 1. Rise slowly (1/2 speed) 2. Drifts rapidly downwards when centered. after a few inches the rate slows. 3. When it is exhibiting this condition, it also drops very perceptively (couple of inches) when the boom is attempting to raise. At other times the boom works fine. Replaced boom circuit relief valve, and checked the centering springs of the bucket and the boom spools to no avail. Looking for suggestions!!
 

mllud

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Jun 29, 2007
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Is your hyd. oil level good. If mine gets low it acts similar. Sounds like you were working in the right place. Your gear pump may have a problem? Acts like it would if you had air in your system. Mike
 

mllud

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It seems like you started working in the right place.Im sure you have checked your hyd. oil. It would act similar with air in the system.I dont know if a failing gear pump would act like that. Mike
 

mllud

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It seems like you started working in the right place.Im sure you have checked your hyd. oil. It would act similar with air in the system.I dont know if a failing gear pump would act like that. Mike
I thought I lost that first post. Crazy
 

Tazza

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It seems like you started working in the right place.Im sure you have checked your hyd. oil. It would act similar with air in the system.I dont know if a failing gear pump would act like that. Mike
When you mention the arms falling i sort of suspect your load checks too. These are used to hold your high pressure in place to prevent the load from dropping when you activate the controls.
 
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dbolt

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When you mention the arms falling i sort of suspect your load checks too. These are used to hold your high pressure in place to prevent the load from dropping when you activate the controls.
Thanks to all who have replied to my posting. Oil is in good condition, and full all other hydraulics working fine (bucket and aux) so presume pump is ok and when the problem is not occuring, lifts great, holds great. Will investigate the checks, The manual indicates a "plug and orings" does anyone know if / how this affects this problem? Thanks again to all who responded.
 

Tazza

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Thanks to all who have replied to my posting. Oil is in good condition, and full all other hydraulics working fine (bucket and aux) so presume pump is ok and when the problem is not occuring, lifts great, holds great. Will investigate the checks, The manual indicates a "plug and orings" does anyone know if / how this affects this problem? Thanks again to all who responded.
If the plug and O-rings are on your load checks yes it will.
I had an old 731 that i could lift the arms up shut the machine down and you could see the lift arm sticks retracting, would have been a few inches/minute. I replaced the ram seals, no change! I pulled the control block and re-sealed it. When i pulled the load checks out the O-rings and backup rings were shredded. Re-installed the control block and it was spot on! Was a great machine!
 
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dbolt

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If the plug and O-rings are on your load checks yes it will.
I had an old 731 that i could lift the arms up shut the machine down and you could see the lift arm sticks retracting, would have been a few inches/minute. I replaced the ram seals, no change! I pulled the control block and re-sealed it. When i pulled the load checks out the O-rings and backup rings were shredded. Re-installed the control block and it was spot on! Was a great machine!
Thanks to all who posted to my problem.. Got it fixed...piston was loose on one of the boom lift cylinders. Mechanic indicated that this is a frequent problem on the NH skid loaders. Thought I would offer this as other may need the same fix....
 

Tazza

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Thanks to all who posted to my problem.. Got it fixed...piston was loose on one of the boom lift cylinders. Mechanic indicated that this is a frequent problem on the NH skid loaders. Thought I would offer this as other may need the same fix....
All my cylinders had Loctite on the threads for that exact reason. Its surprising yours wasn't done too.... I hope the movement didn't cause too much damage!
 

skidsteer.ca

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All my cylinders had Loctite on the threads for that exact reason. Its surprising yours wasn't done too.... I hope the movement didn't cause too much damage!
I have seen where poly pac piston seals will diplay intermittant symtoms like this too. They get torn and depending on how the loose piece ends up back in the hole in the seal they may leak or not for a period of time before they really fail badly.
Ken
 

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