Link Belt 160lx hydraulic issues

[MikeRandazzo]

2004 link belt 160lx excavator
S/N K2J16053
4,300hrs

Two days ago, machine ran great, good power, all functions worked as they should. By the end of the day I noticed the stick (dipper) function slowed down considerably. I shut the machine down for the evening and returned to job the next morning.

Upon start up to warm the machine up, without the hydraulic control lever engaged the stick automatically went out all the way and I could not get it to come back in with the controls. I also noticed bucket function was very slow.

I shut the machine down with the boom raised and the stick drifted in to the 90 degree position (straight up and down).

Had dealer come out and they were pretty much dumb founded. The road tech snapped an allen wrench off trying to get the pilot pump off. After this he left assuming the pilot pump was bad. Next morning I successfully removed the pilot pump to look at the gears inside and everything looked great.

Has anyone ever experienced anything like this? Where should I be looking? I took the valves out of the main valve block for the stick function and everything looked good, no springs or seats broken.

All filters and fluid look fine to me.

 

[Acecadet]

Did you take the pilot section apart on the stick valve? This is where tiny debris can really cause trouble. It takes some really bad stuff to hang up a hydraulic spool. Just a bit of o ring or the inside of a hose deteriorating can plug up the small openings in the pilot section.

 

[uffex]

Good day
Cylinder seal allowing by-pass will always extend the arm may well be worth checking this out first.
Kind regards
Uffex

 

[MikeRandazzo]

Did you take the pilot section apart on the stick valve? This is where tiny debris can really cause trouble. It takes some really bad stuff to hang up a hydraulic spool. Just a bit of o ring or the inside of a hose deteriorating can plug up the small openings in the pilot section.

Thank you for the quick response…I did not take the pilot valves out, I took the valves for stick function out of the main valve….they were clean and nothing unusual, I would imagine the pilot valves would be right behind the cab?

 

[MikeRandazzo]

Good day
Cylinder seal allowing by-pass will always extend the arm may well be worth checking this out first.
Kind regards
Uffex

Uffex,
Thank you for the timely reply. Even with the hydraulic control lever not engaged in the cab? And when the stick goes all the way out I can shut the machine down and it will come down to 90 degrees slowly by itself. I did just have the stick cylinder repacked about 35 hrs ago…I will definitely be looking into having it taken apart. I figured the cylinder bypassing would make it go out like that but what’s confusing is that it will do it as soon as I start the machine and do not even engage the controls.

 

[John C.]

I would add to uffex's post that it is likely that the packing was damaged when the cylinder and rod were mated back up. I would suggest removing the hydraulic return filter and looking for packing material.

 

[92U 3406]

What made them suspect the pilot pump? Seems like a case of lets throw parts at this machine. Symptoms don't even really point to a pilot pressure problem.

 

[MikeRandazzo]

I would add to uffex's post that it is likely that the packing was damaged when the cylinder and rod were mated back up. I would suggest removing the hydraulic return filter and looking for packing material.

This will be the next step after I take a look at the pilot valves for stick in/stick out function.

thank you for the response and insight!

 

[MikeRandazzo]

What made them suspect the pilot pump? Seems like a case of lets throw parts at this machine. Symptoms don't even really point to a pilot pressure problem.

Quite honestly I have no idea…it didn’t make sense to me what the tech was saying and doing…I will check filters again, check pilot valve for stick in and out and of nothing else I guess I’ll be taking the stick cylinder back off to have it inspected. Thank you for your response and insight!

 

[uffex]

Good day
Attached may help out.
Kind regards
Uffex

 

[MikeRandazzo]

Good day
Attached may help out.
Kind regards
Uffex

Good morning UFFEX,

would you start looking into the pilot controls with the symptoms I have stated or would you inspect the internals of the stick cylinder first?
Any input would be appreciated.

Thank You

 

[uffex]

Good day Mike
If you can drag the arm in the out (Cylinder in) position, raise the boom as the arm drift's inwards raise the control lock out barrier (Safety) if the arm stops it means your issue is with the pilot system, if it continues to drift inwards I would be more inclined to suspect the cylinder or debris from the original failure. Come back with the results I will try to help some more.
Kind regards
Uffex

 

[MikeRandazzo]

Good day Mike
If you can drag the arm in the out (Cylinder in) position, raise the boom as the arm drift's inwards raise the control lock out barrier (Safety) if the arm stops it means your issue is with the pilot system, if it continues to drift inwards I would be more inclined to suspect the cylinder or debris from the original failure. Come back with the results I will try to help some more.
Kind regards
Uffex

Uffex,

The arm automatically goes out without the safety engaged to unlock the controls and I cannot bring the arm back in with the controls unlocked. The safety lever does not affect the arm cylinder from stopping automatically going out. If I shut the machine down with the boom raised, the arm will drift back into a 90 degree position (straight up and down). That being said, should the valves allow flow to the arm cylinder to make it go out automatically?

Thank You

 

[uffex]

Good day Mike
I need to be sure that I am understanding your post exactly please look at the attchment and confirm if I have the correcct pitcure.
Kind regards
Uffex

 

[MikeRandazzo]

Good day Mike
I need to be sure that I am understanding your post exactly please look at the attchment and confirm if I have the correcct pitcure.
Kind regards
Uffex

UFFEX,

this is EXACTLY my issues

 

[uffex]

Ok Mike first I would suggest a pilot pressure issue would affect more than just the arm, I would suggest a likely cause of the issue is that of debris from the original cylinder failure has lodged the spool in the open position. Fortunately, checking this out is not so difficult while my Link belt information is not as good as I would like I will assemble some information for you.
Kind regards
Uffex

 

[MikeRandazzo]

Ok Mike first I would suggest a pilot pressure issue would affect more than just the arm, I would suggest a likely cause of the issue is that of debris from the original cylinder failure has lodged the spool in the open position. Fortunately, checking this out is not so difficult while my Link belt information is not as good as I would like I will assemble some information for you.
Kind regards
Uffex

Thank you sir, I will wait to hear from you!

 

[uffex]

Hi Mike
Please see attached.
Kind regards
Uffex

 

[MikeRandazzo]

Hi Mike
Please see attached.
Kind regards
Uffex

Uffex,
Will do this tomorrow and report back, thank you as always.

 

[MikeRandazzo]

Uffex,
Will do this tomorrow and report back, thank you as always.

UFFEX,

I checked the difference between the Arm spool 1 and Arm spool 2, there is roughly a 5mm difference between the two…I am thinking this is where my issue lies. I would imagine the distances from the edge of the valve blocks should be identical and one is stuck in place allowing free flow to extend the arm automatically. Please let me know what you think.

Thank you as always