help i was using it to day and all of a sudden the boom started only going up when i boom down is goes up slow when i boom up it goes up normal this is a 2006 Hitachi zx160lc no dash S/N FF01F1Q006474 any idea where to start i have a drzx and a presser test set thanks in advances
Does the boom stay still with the joystick centered?
it does bleed off real slow it has done that for a long time
it does bleed off real slow it has done that for a long time
Check for a stuck plunger on the joystick first. After that I would check the pilot pressure at the main valve spool ends for the boom. If that pressure is comparable per side, it will be time to approach an issue with the main valve centering or a sticking valve spool.
Just started checking some more information it does not mater what Joy stick I move or which way I more them the boom goes up. The "boom up pilot" reads MPA ~75 when raising boom, and when I move any other direction with the joy sticks it reads about MPA ~30 for a split second. Boom angel reads .25 volts no matter the angel.
This is sounding like your main control spool has an issue.
I think you are right with the pilot boom up disconnected it still went up Any way to test the main spool? And where is it located And thank you thank you for all the help
You can follow the boom cylinder hoses to the main control valve. Then follow the pilot lines to where they go to on the main control valve. Make sure all your moving functions are rested on the ground before you disconnect anything. I would remove the spool caps on each side first and see if one of the centering springs is broken and wedged inside the cap. Once the caps are off you should be able to freely move the spool back and forth..........if not something is in the spool bare and is preventing it from proper movement. Since you stated that the boom had been previously drifting, I'm thinking there is part of a cylinder packing wedged in there somewhere. I am not extremely familiar with your particular machine hydraulics, so I don't have a schematic to guide you with. What info I'm giving you is "general rule of thumb". Taking pics of the main valve may help. I believe the pic you took is of the pilot manifold.
You can follow the boom cylinder hoses to the main control valve. Then follow the boom pilot lines to where they go to on the main control valve. Make sure all your moving functions are rested on the ground before you disconnect anything. I would remove the boom spool caps on each side first and see if one of the centering springs is broken and wedged inside the cap. Once the caps are off you should be able to freely move the spool back and forth..........if not something is in the spool bore and is preventing it from proper movement. Since you stated that the boom had been previously drifting, I'm thinking there is part of a cylinder packing wedged in there somewhere. I am not extremely familiar with your particular machine hydraulics, so I don't have a schematic to guide you with. What info I'm giving you is "general rule of thumb". Taking pics of the main valve may help. I believe the pic you took is of the pilot manifold.
Site was lagging bad.............sorry for 2 responses saying the same dam thing.
No problem on the double post I had the same problem yesterday I do have the tickets Manu I was not sure if you were talking about the boom spool or something else Now I under stand And yes I did my pilot test at the manifold And I can't thank you a nuf For pointing me in the right direction Do you know if the spool can be rebuilt or just replace Thanks again
There really isn’t anything to rebuild. Once the spool is removed you can used compressed air and clean the bore. Use some fine Emory cloth and clean up any scratches on the spool, then lube it with clean oil and stick it back in the bore. If it slides back and forth easily with your fingers then you are done. If it still sticks there is a possibility the spool may be bent. That’s a bit trickier but possible.
Thanks Will let you know what happens
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
Good day Similar situation, the piston head had become divorced from the piston rod. If you can by using the shock valve lower the bucket to the ground when you raise the boom, you will hear a clonk from the boom cylinders. Kind regards Uffex
Well went to work on it today I got 1 side opened up the swing spool is real tight there are no burbs I cleaned it with 800 grit papper and then cleaned it it did not chang it at all so I took a difrent spool to test the boor and it was OK so I think I have a bent spool with that said I have no problem with the swing And then the snow hit so I had to cover it up and leave I will check to see if the spool is bent is it OK as long as I don't have any problems with the swing Thanks
I’m not understanding why your messing with the swing spool. It didn’t have an issue did it? Don’t use different spools in different bores……they are machine fitted.
Sorry I was moving them all to check for free movement I take it that was a mistake And correct swing is working Don't you just love working with amateurs I hop I did not mes up to bad
Have you tried the boom spool yet. Concentrate on that one
i saw i guy use that as a testing method. Port fluid on the retract side and if the cylinder extends its bad seals.
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
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
If you take care of it now it’s the difference between $300 and $3000. The machine has already given you a warning……proceed with caution.
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
1 foot in 10 minutes is way too much.
They do. Bucket loaded and curled, arm all the way out. Maximum drift is 15mm in 5 minutes measured at the bucket to ground.
In your professional opinion Next step redo the boom cylinders
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
I agree, that is just what the manual says. Later units have specs for rod travel so you are not subject to the influence of other cylinders leaking.
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.
LOL.....thats like almost nothing! 12" in 10 minutes? It may be 5 feet in 10 minutes stretched out.
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
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.
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.
I see, thank you
I believe this video represents some of whet Vtech63 is talking about.
You are right again got one cylinder pulled apart the best I could it was put together wrong the cushion was in backwards the shim was on the wrong end the wrong end the nut was not even finger tight there was no set screw in it As with every problem I have had on this machine it has been from whoever worked on it before they messed everything up I cannot get the piston off it moves about a 1/2 inch and that's as far as it'll come off I believe part of the scheme has gotten wedged in there My plan is to use a hydraulic pull to get it off let me know if this is a mistake or if you have a better idea again thank you for your help
Well the snow finally all melted away So I got the other side done today It was not as bad but the set screw was lose and the nut was finger tight but it was put together right I Maseru the bleed off at the boom it was 3/4" on 10 minutes I will check the anti drift valve next unless you got a better suggestion Thanks
Cleaned the anti drift valve solid as a rock now I learned a lesson I need a o ring the kit I had had the standard rings so I put in the right size for the valves cover did it 3 times The o ring was pinching in to the spring and leaking I went to the shinny o rings that it had and problem solved Thanks for the help