Control valve?

   / Control valve? #1  

TSMART

Silver Member
Joined
Jul 11, 2005
Messages
200
Location
central florida
Tractor
jinma jm 224
Koyker 160. (2004) Bucket uncurls completely within 60 seconds. Within the same 60 seconds the main loader lowers from all the way up to halfway where it stops and stays there. Main hydraulic cylinder rebuilt a month ago; no problems till this started. No visible leaks. No air in lines. Control valve?? Or is this related to the rebuilt cylinder? Hydraulic fluid is full. Need advise thanks. Control valves pricey.
 
   / Control valve? #2  
Some questions:
Are you saying that while the bucket is uncurling (dumping) the loader also lowers to midpoint un-commanded (no up or down movement at the joystick)?
Can you raise and lower the loader completely without rolling the bucket?
Were both lift cylinders rebuilt?
Are you able to raise the front end of the tractor with the loader?
Can you hear anything that sounds like a pressure relief valve opening (like the sound it makes when a cylinder hits end of travel)?

You could swap the hoses at the control valve so that the "up/down" movement controls the bucket tilt and the "left/right" movement controls the loader lift. Awkward to use but would be useful indicator if the problem stays with the lift cylinders or if it stays with the control valve movements.
 
   / Control valve? #3  
I'll add to Piper's post:
Do you have a regen detent in your valve that lets you dump the bucket quickly, or a float position for the lift arms?
When you say "main hydraulic cylinder" what do you mean? There are two bucket cylinders, and two lift cylinders
 
   / Control valve?
  • Thread Starter
#4  
Some questions:
Are you saying that while the bucket is uncurling (dumping) the loader also lowers to midpoint un-commanded (no up or down movement at the joystick)?
Can you raise and lower the loader completely without rolling the bucket?
Were both lift cylinders rebuilt?
Are you able to raise the front end of the tractor with the loader?
Can you hear anything that sounds like a pressure relief valve opening (like the sound it makes when a cylinder hits end of travel)?

You could swap the hoses at the control valve so that the "up/down" movement controls the bucket tilt and the "left/right" movement controls the loader lift. Awkward to use but would be useful indicator if the problem stays with the lift cylinders or if it stays with the control valve movements.
I can lift the bucket all the way up but itll come down to halfway then stop. Within a minute. I can completely curl in the bucket but soon as I'm off the stick itll totally uncurl in a minute. One lift cylinder was rebuilt a month ago. I have not tried to lift front end with the bucket. Will do so first thing tomorrow.
 
   / Control valve?
  • Thread Starter
#5  
I'll add to Piper's post:
Do you have a regen detent in your valve that lets you dump the bucket quickly, or a float position for the lift arms?
When you say "main hydraulic cylinder" what do you mean? There are two bucket cylinders, and two lift cylinders
Lift cylinder rebuilt a month ago. I can float the bucket.
 
   / Control valve? #6  
I can float the bucket.
You should not be able to float the bucket, but you should be able to float the lift arms if circuits are plumbed correctly. So you do not have a regen circuit? Does it make any difference if the engine is running?
It sounds to me like a hydraulic lock is being created, but goes away when the joystick is moved.
 
   / Control valve? #7  
Koyker 160. (2004) Bucket uncurls completely within 60 seconds. Within the same 60 seconds the main loader lowers from all the way up to halfway where it stops and stays there. Main hydraulic cylinder rebuilt a month ago; no problems till this started. No visible leaks. No air in lines. Control valve?? Or is this related to the rebuilt cylinder? Hydraulic fluid is full. Need advise thanks. Control valves pricey.
let the pressure off and check quick connects for small amounts of water. Just small amounts of moisture / water can cause that.
 
   / Control valve? #8  
What you are describing is a leak down issue. The bucket leaks down all the way but the loader arms only leak down halfway.

The two things that can cause this that I know of are internal cylinder leakage (from one side of the piston to the other) or an internal leak in the control valve where fluid is leaking past a part that is supposed to be blocking it.

Unless fluid is leaking out of the quick connects, I can not see how they could be involved at all, water or not. Most hydraulic fluids contain emulsifiers that hold water in suspension of the fluid so that it will not pool up in the bottom of the tank or freeze solid. If you have water in the fluid it will most likely have a milky appearance to it.
That raises the question of what fluid are you using?
Also, why was the one cylinder rebuilt and what was done to it?
If you raise the loader all the way up and push the joystick into "float" how does it behave? Does it come down gently or slam like it has been dropped?
Did this issue start immediately after re-installing the repaired cylinder or did it work fine for a while before this started happening?
Does it leak down at the same rate with the engine off as it does with the engine running? (not sure why this would matter but it might be a clue)
 
   / Control valve?
  • Thread Starter
#9  
What you are describing is a leak down issue. The bucket leaks down all the way but the loader arms only leak down halfway.

The two things that can cause this that I know of are internal cylinder leakage (from one side of the piston to the other) or an internal leak in the control valve where fluid is leaking past a part that is supposed to be blocking it.

Unless fluid is leaking out of the quick connects, I can not see how they could be involved at all, water or not. Most hydraulic fluids contain emulsifiers that hold water in suspension of the fluid so that it will not pool up in the bottom of the tank or freeze solid. If you have water in the fluid it will most likely have a milky appearance to it.
That raises the question of what fluid are you using?
Also, why was the one cylinder rebuilt and what was done to it?
If you raise the loader all the way up and push the joystick into "float" how does it behave? Does it come down gently or slam like it has been dropped?
Did this issue start immediately after re-installing the repaired cylinder or did it work fine for a while before this started happening?
Does it leak down at the same rate with the engine off as it does with the engine running? (not sure why this would matter but it might be a clue)
Ok. I have a few more clues. Can I lift front of tractor off ground? Yes, but only for a second. When I drop the lift from way up, yes it comes down very quickly. Another clue: my boot on control arm broken for years. Since tractor was kept dry I figured no problem. But now you have me thinking I might have moisture in there. I know that in front of the seat there is a stack which controls speed of drop. Wondering if I should adjust or tighten. None of this affects the 3 point. It works fine. Thank you again for your assistance.
 
   / Control valve?
  • Thread Starter
#10  
The cylinder was rebuilt because it was leaking badly. Using hydraulic fluid. It has a spin on hydraulic filter.
 

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