Help me diagnose a hydraulic issue with my loader

[DOCatRU]

Once the tractor is at operating temp.....put a load on the forks and take a measurement. Wait a given time, however long it takes to make a measurable/noticable difference. Record movement vs time....

Now repeat the test with the quick couplers unhooked. Now be careful. They are under pressure and won't uncouple and recouple easily. But since you ONLY need to isolate the curl......you can uncouple them with the tractor off and loader on the ground and bled. Then with them unhooked, you simply restart the tractor, raise the loader, and start the timer.

It can be the valve or the cylinders with the curl circuit.

Contrary to what some believe....there are NO seals in the valve that can cause this. The valve spools are metal on metal....and thus "some" internal leakage is expected....and most valves have a spec on the amount of fluid per hour at a given pressure.

But no need to get into all that just yet.

First thing.....is this repeatable? Does it happing constantly and continuously Everytime you have a load on? Cause if not....I'd chalk it up to a little piece of debris, or the valve not coming back to perfect neutral and no worry about it any longer.

Second thing to do is isolate the cylinders from the valve. Do this by uncoupling the quick connects.

Once the tractor is at operating temp.....put a load on the forks and take a measurement. Wait a given time, however long it takes to make a measurable/noticable difference. Record movement vs time....

Now repeat the test with the quick couplers unhooked. Now be careful. They are under pressure and won't uncouple and recouple easily. But since you ONLY need to isolate the curl......you can uncouple them with the tractor off and loader on the ground and bled. Then with them unhooked, you simply restart the tractor, raise the loader, and start the timer.

Please report back the results of this simple test.

Hi LD1:

Thanks for the test instructions.

With the tractor at temperature and idling, it took 1 minute 45 seconds for the bucket to tip down 18" with a load of approximately 800 lb.

I did bleed the cylinder, but could not get the quick attach coupling off.

If this matters, with the tractor off it took 35 seconds for the buck to tip down 18 inches.

There is no perceivable leakage of hydraulic fluid from the bucket cylinder.

What's your best guess?

 

[LD1]

Hi LD1:

Thanks for the test instructions.

With the tractor at temperature and idling, it took 1 minute 45 seconds for the bucket to tip down 18" with a load of approximately 800 lb.

I did bleed the cylinder, but could not get the quick attach coupling off.

If this matters, with the tractor off it took 35 seconds for the buck to tip down 18 inches.

There is no perceivable leakage of hydraulic fluid from the bucket cylinder.

What's your best guess?

Tractor on or off does nothing to isolate the valve from the cylinder. And its actually odd that it bled down quicker with the tractor off.

Have you ever removed the loader before? Same process on the couplers.....just unhook ONLY the ones for the curl. Then fire it back up and raise the load. Really need to be able to do this so you can record the difference between cylinders AND valve in play vs JUST the cylinders with the valve unhooked.

Another thing you can try/notice but not as conclusive.......

When you do the test and let it bleed down......IF its the cylinders and NOT the valve.....as the rod extends the fluid in the cylinders will bypass the piston seals, but at the same time it will suck air into the system, likely from the gland seals, to replace the area that the cylinder rod once occupied.

So....if the cylinders are leaking by.....at the end of your test and 18" drop you should have a nice pocket of air in the cylinder. See if the machine exhibits any symptoms of that. Either by a few second delay when trying to curl after the test (delay while the fluid enters the air cavity in the cylinder but doesnt cause movement because the cylinder isnt full yet). Or without moving the curl....the bucket or forks will appear to "flop" around and not held rigid in place due to the air pocket in the cylinder compressing.

 

[DOCatRU]

Tractor on or off does nothing to isolate the valve from the cylinder. And its actually odd that it bled down quicker with the tractor off.

Have you ever removed the loader before? Same process on the couplers.....just unhook ONLY the ones for the curl. Then fire it back up and raise the load. Really need to be able to do this so you can record the difference between cylinders AND valve in play vs JUST the cylinders with the valve unhooked.

Another thing you can try/notice but not as conclusive.......

When you do the test and let it bleed down......IF its the cylinders and NOT the valve.....as the rod extends the fluid in the cylinders will bypass the piston seals, but at the same time it will suck air into the system, likely from the gland seals, to replace the area that the cylinder rod once occupied.

So....if the cylinders are leaking by.....at the end of your test and 18" drop you should have a nice pocket of air in the cylinder. See if the machine exhibits any symptoms of that. Either by a few second delay when trying to curl after the test (delay while the fluid enters the air cavity in the cylinder but doesnt cause movement because the cylinder isnt full yet). Or without moving the curl....the bucket or forks will appear to "flop" around and not held rigid in place due to the air pocket in the cylinder compressing.

LD1:

Thanks again for the advice. I went out and took a second crack at it. This time I was able to get one of the quick attach couplings off. The line that controls rollback (white).

I can get three of the four hydraulic lines off of the cylinder. The two down by the moving rod and only one of the lines by the cylinder end. The other one won't budge for now. Even with several applications of PB blaster. I'm going to soak that connection with my homemade "creeping oil" (Kroil, acetone and automatic trans fluid) to see if that helps.

In any case, With the rollback quick attach coupling off I raised the bucket. This time after 1:30 the bucket did not tilt down AT ALL!

So, any further guess?

Thanks again, in advance for the advice.

DOC

 

[LD1]

Well you only need to unhook two lines, as there should only be 2 for the curl and two for the lift.

But on any case.......if you truly isolated the cylinders from the valve, and it sounds like you have, and the problem went away.....then it isnt the cylinders causing you issues it is "something" to do with the valve.

It could be a number of things. But I would start by taking the can off the back of the valve for the curl function. Usually two or three bolts, and its just a cover. The actual spool protrudes BOTH sides of the valve. One side your lever (or cable to a joystick) hook to to control the function. The other end has the return springs and detent mechanism if applicable (like holding position in float for the lift). The "can" just covers and protects all that. Make sure there isnt crud and junk in there, or a broken spring causing the valve to not fully return to its closed neutral state.

If thats all good, its simply a matter of the valve being either worn out (if this was never a problem before) or its just a cheap valve. And the only remedy is likely replacement.

If the valve has load checks....you can try taking them out and making sure nothing is broken or debris in there.

If it were mine, Id take the valve apart and see what the condition of the spool and bores look like. But I dont know your mechanical ability. And if its something you cannot live with....time for a replacement. But at least you didnt waste money like so many people do rebuilding cylinders when they arent the problem because they fail to do basic troubleshooting.

 

[SPYDERLK]

I lived with that slow leak down FEL syndrome for a long time, just learned to compensate.

Last year I had a hydraulic failure that had me do a thorough overhaul of the front C/S driven hydraulic circuit.
Thinking my pump was shot I opened it to diagnose only to find it A-OK but the shaft was rusty where the seal met it.
I polished that shaft, installed a new seal (used the old one as a back up to prevent crud intrusion)'
Fortunately there was enough space to accept that dual seal mod.

Wow! I can now leave my FEL elevated and 24 hrs later it has not moved. Joy!
(NB: only that one elevated time just 4 testing as one should never do so for safety consideration)

Things at the pump should not affect leakdown.

 

[DOCatRU]

Well you only need to unhook two lines, as there should only be 2 for the curl and two for the lift.

But on any case.......if you truly isolated the cylinders from the valve, and it sounds like you have, and the problem went away.....then it isnt the cylinders causing you issues it is "something" to do with the valve.

It could be a number of things. But I would start by taking the can off the back of the valve for the curl function. Usually two or three bolts, and its just a cover. The actual spool protrudes BOTH sides of the valve. One side your lever (or cable to a joystick) hook to to control the function. The other end has the return springs and detent mechanism if applicable (like holding position in float for the lift). The "can" just covers and protects all that. Make sure there isnt crud and junk in there, or a broken spring causing the valve to not fully return to its closed neutral state.

If thats all good, its simply a matter of the valve being either worn out (if this was never a problem before) or its just a cheap valve. And the only remedy is likely replacement.

If the valve has load checks....you can try taking them out and making sure nothing is broken or debris in there.

If it were mine, Id take the valve apart and see what the condition of the spool and bores look like. But I dont know your mechanical ability. And if its something you cannot live with....time for a replacement. But at least you didnt waste money like so many people do rebuilding cylinders when they arent the problem because they fail to do basic troubleshooting.

Thank you so much, LD1.

I guess you are talking about the joy stick valve. Is this correct?

I have pdf copies of the shop manuals for the CK 30 and I am a pretty proficient shade tree mechanic.

I'm looking over the exploded parts diagram and pages of explanation.

It's a double spool remote control valve with load check valves in the spool passages.

I'll start puzzling my way through this.I guess I have few hours ahead of me crawling in the dirt under the tractor!

DOC

 

[LD1]

Yes its a double spool valve. And yes I am talking about the the joystick valve.

Some tractors have the joystick mounted directly to the valve itself. Other tractors....particularly on cabbed models....use cables to control the valve spool movement. So that is something else to check too. IF it is cable operated....make sure cables arent binding.

There are NO seals in the valve that seal the work ports and passages in the spool. It is very precision ground and tight tolerance stuff. With there being no seals....a minimal amount of internal leakage (which would result in cylinder drift) is considered acceptable. How much is all up to the manufacture of the valve and how cheaply or expensive they made the valve.

As they age and wear, leakage (and cylinder drift) becomes more and more noticeable. But at 900hrs on the machine you shouldnt be experiencing this much drift unless neglected like never changing oil and filters or using the wrong oil or allowing crud in the system from careless oil changes like debris on top of the bucket falling in, or around the fill hole.

I am not sure if you ever answered this....but is this a new problem? Or is it something that has progressively gotten worse?

Going from unnoticeable to 15" drift in a minute or two is a big sudden change that would seem to indicate something other than wear. As if it was just wear over time it progress rather slowly....from being almost unmeasurable....to just a few inches a minute....to maybe 6" a minute a few hundred hours later, etc

 

[DOCatRU]

Yes its a double spool valve. And yes I am talking about the the joystick valve.

Some tractors have the joystick mounted directly to the valve itself. Other tractors....particularly on cabbed models....use cables to control the valve spool movement. So that is something else to check too. IF it is cable operated....make sure cables arent binding.

There are NO seals in the valve that seal the work ports and passages in the spool. It is very precision ground and tight tolerance stuff. With there being no seals....a minimal amount of internal leakage (which would result in cylinder drift) is considered acceptable. How much is all up to the manufacture of the valve and how cheaply or expensive they made the valve.

As they age and wear, leakage (and cylinder drift) becomes more and more noticeable. But at 900hrs on the machine you shouldnt be experiencing this much drift unless neglected like never changing oil and filters or using the wrong oil or allowing crud in the system from careless oil changes like debris on top of the bucket falling in, or around the fill hole.

I am not sure if you ever answered this....but is this a new problem? Or is it something that has progressively gotten worse?

Going from unnoticeable to 15" drift in a minute or two is a big sudden change that would seem to indicate something other than wear. As if it was just wear over time it progress rather slowly....from being almost unmeasurable....to just a few inches a minute....to maybe 6" a minute a few hundred hours later, etc

Once again, you are giving me great information. Yes, my joystick is connected by cables to the valve which is mounted underneath just behind the front wheel.

This is a brand new problem.

A few weeks ago I did some brush hogging through some high stuff which had small branches mixed in. I'm going to crawl around underneath tomorrow and see if I can see any damage. I'll check for crud and perhaps remove the cover of the number 2 spool (which controls dump functions) to see what might be going on.

I have performed all of the scheduled fluid changes since I bought the tractor with 400 hours. I have been studying the shop manual which outlines which spools control the functions.

I'll let you know what I find out. Crossing my fingers that there is a simple explanation.

DOC

 

[PILOON]

Just a suggestion to try to isolate your problem.
A leaky quick connection might also be the cause as it takes very little leakage to lose pressure.
Are yours all nice and clean? or an oily messy area.
Just a 2 cent thought.

 

[LD1]

Worth a shot, but for it to leak down 15" in a little over a minute, I'd expect a puddle under wherever the quick couplers are.

Just a suggestion to try to isolate your problem.
A leaky quick connection might also be the cause as it takes very little leakage to lose pressure.
Are yours all nice and clean? or an oily messy area.
Just a 2 cent thought.