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help zx160lc when i boom down boom goes up

nowing75

Senior Member
Joined
Aug 5, 2009
Messages
898
Location
coatesville indiana
Good day
May not be the case however if the piston has sufficient leakage (bypass) the cylinder's will always extend to displace the fluid puping in.
Kind regards
Uffex
i saw i guy use that as a testing method. Port fluid on the retract side and if the cylinder extends its bad seals.
 

Btad

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Jun 7, 2021
Messages
111
Location
Vancouver wa
Have you tried the boom spool yet. Concentrate on that one
You are my hero
The spool was stuck I had to put a pry bar in the top spring to get it out I did not have to pry hard but I could not pull it out by hand i could not see any problems with it put it back in and it moved good so put it back to gether and it works again the doom still bleeds off slow like a foot in 10 minutes
But with all that said if it happens again I can fix it in about 30 minutes
I am a a pretty good mechanic bit I never worked on hydraulic before now
So thanks again
 

terex herder

Senior Member
Joined
Nov 10, 2017
Messages
1,778
Location
Kansas
My guess is there was a piece of contamination that stuck the spool. Watch for signs of something in the hydraulic system coming apart. Hopefully the contamination was a piece of the bad piston seal that is allowing your boom to drift.
 

Btad

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Jun 7, 2021
Messages
111
Location
Vancouver wa
My guess is there was a piece of contamination that stuck the spool. Watch for signs of something in the hydraulic system coming apart. Hopefully the contamination was a piece of the bad piston seal that is allowing your boom to drift.
I will probably look at the boom cylinder
One of these day soon when I get a chance
 

aongheas.macask

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Joined
Nov 12, 2008
Messages
105
Location
Scotland
Occupation
ex service manager
You are my hero
The spool was stuck I had to put a pry bar in the top spring to get it out I did not have to pry hard but I could not pull it out by hand i could not see any problems with it put it back in and it moved good so put it back to gether and it works again the doom still bleeds off slow like a foot in 10 minutes
But with all that said if it happens again I can fix it in about 30 minutes
I am a a pretty good mechanic bit I never worked on hydraulic before now
So thanks again
where did you measure the foot,was it on the cylinder or at the bucket,all excavators will have a certain amount of drift
On the cylinders unless you have load control / counterbalance valves fitted on the cylinder. Cat should be able to give you the allowable drift measurement
 

aongheas.macask

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Nov 12, 2008
Messages
105
Location
Scotland
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ex service manager
where did you measure the foot,was it on the cylinder or at the bucket,all excavators will have a certain amount of drift
On the cylinders unless you have load control / counterbalance valves fitted on the cylinder. Cat should be able to give you the allowable drift measurement
Sorry, Hitachi should give you allowable drift measurement
 

aongheas.macask

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Joined
Nov 12, 2008
Messages
105
Location
Scotland
Occupation
ex service manager
They do. Bucket loaded and curled, arm all the way out. Maximum drift is 15mm in 5 minutes measured at the bucket to ground.
They do. Bucket loaded and curled, arm all the way out. Maximum drift is 15mm in 5 minutes measured at the bucket to ground.
Seems strange to measure at the bucket,I would always measure at the hoist cylinder for an accurate reading if you suspect that is the one that is drifting, also if you suspect piston seals are bypassing them an easy test is to fully extend cylinder and hold against relief valve for a few minutes and if piston seals are bypassing the cylinder will beat up rapidly in the area where the piston sits.
 

aongheas.macask

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Joined
Nov 12, 2008
Messages
105
Location
Scotland
Occupation
ex service manager
Seems strange to measure at the bucket,I would always measure at the hoist cylinder for an accurate reading if you suspect that is the one that is drifting, also if you suspect piston seals are bypassing them an easy test is to fully extend cylinder and hold against relief valve for a few minutes and if piston seals are bypassing the cylinder will beat up rapidly in the area where the piston sits.
should read heat up not beat up
 

Vetech63

Senior Member
Joined
Aug 10, 2016
Messages
6,362
Location
Oklahoma
They do. Bucket loaded and curled, arm all the way out. Maximum drift is 15mm in 5 minutes measured at the bucket to ground.
LOL.....thats like almost nothing! 12" in 10 minutes? It may be 5 feet in 10 minutes stretched out.:eek:
 

Btad

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Joined
Jun 7, 2021
Messages
111
Location
Vancouver wa
Yeah ASAP! You could crater the cylinder and contaminate the entire hydraulic system. What you just dealt with is nothing compared to what that catastrophe while be.
Will order parts Monday morning
Any thing special that I should know when I put in new seal kits in
Won't the filter catch ant of the seal do it won't contaminat the system?
And again thank you do much
 

Vetech63

Senior Member
Joined
Aug 10, 2016
Messages
6,362
Location
Oklahoma
If you have trouble with the seal kit replacement just post pics. There are several different types of glands and I don’t know which you have.
The system is filtered on the low/return side of the system. A failure in 1 circuit can contaminate the others through the common control valve. As you use the failing circuit, the return side feeds back into the main control valve which may make that return oil available for the following circuit if it is being used at the same time. A lot of this also depends on the type of control valve your machine is equipped with, whether it’s open/closed center and open/closed port.
 

Acoals

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Wisconsin
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Jack of all trades/Master of none
Yeah ASAP! You could crater the cylinder and contaminate the entire hydraulic system. What you just dealt with is nothing compared to what that catastrophe while be.

As a general question, how much internal leak down is acceptable without running the risk of causing a major failure as you described? For reference my Cat 315's thumb will weep down, not 12" in ten minutes, but it will drop to the ground overnight from the folded position. I have a couple other functions on different machines that will weep down, or sag if they are holding a load.
Also, what exactly do you mean by "cratering" the cylinder? What would happen internally that would cause this, and what exactly would be cratered, the cylinder walls?
 

Vetech63

Senior Member
Joined
Aug 10, 2016
Messages
6,362
Location
Oklahoma
As a general question, how much internal leak down is acceptable without running the risk of causing a major failure as you described? For reference my Cat 315's thumb will weep down, not 12" in ten minutes, but it will drop to the ground overnight from the folded position. I have a couple other functions on different machines that will weep down, or sag if they are holding a load.
Also, what exactly do you mean by "cratering" the cylinder? What would happen internally that would cause this, and what exactly would be cratered, the cylinder walls?
It’s not necessarily the leak down that bothers me in the op’s situation. It’s the fact that something in that boom circuit is coming apart (I assume it’s the cylinder packing) and a contaminant had already made it’s way to the main valve and hung it up. He only repaired a symptom and not what is causing it. If chunks, big enough to lock up the control spool, are coming off then odds are the metal of the piston can start dragging the sides of the barrel…..beginning a infusion of metal particles into the hydraulic system.
 

Acoals

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It’s not necessarily the leak down that bothers me in the op’s situation. It’s the fact that something in that boom circuit is coming apart (I assume it’s the cylinder packing) and a contaminant had already made it’s way to the main valve and hung it up. He only repaired a symptom and not what is causing it. If chunks, big enough to lock up the control spool, are coming off then odds are the metal of the piston can start dragging the sides of the barrel…..beginning a infusion of metal particles into the hydraulic system.
I see, thank you
 
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