My FEL is bleeding down

[LD1]

Which basically was the point I was trying to make, if there is equal pressure on both sides of the cylinder seal. If you have lower pressure on one side of the than the other, you can have seepage past the seal to equalize the pressure, but because of the volume displacement would be almost unmeasureable

We are talking about hydraulics and not pneumatics. Pressures can equalize with no fluid movement at all. Remember, fluid is not compressible.

As long as "almost immeasurable" means "zero". The only movement that could happen, would be a result of the steel cylinder stretching and/or the rod seal bulging.

:thumbsup:

 

[J_J]

6) Leakage test for the boom cylinders/spool.

Place a load in the bucket that induces a pressure reading in the boom cylinder base end of approximately 1000 psi. Raise to approximately mid-stroke. After a short period of time note the pressure on the rod end side of the boom cylinders. It should be near zero and not increasing. If it is not near zero or is increasing, oil is leaking past one or both of the boom cylinder piston seals and the cylinders need to be repaired or replaced.

If fluid is leaking past the seals, where is it going, and is any parts moving.

Would the loader move at all?

If the seals never leak and things don't move, why are people repairing the seals on the loader cyl.

Why even have seals if they can hold a load without them.

Do you really think they replace all that many valves because of loader leak down?

Mysteries of all mysteries, what is causing the leak down?

How many of you really think the problem is the spool leakage.

It is not hard to test the spool valve, just remove the IN, OUT, and PB hose hoses with the loader raised, and see if any fluid is leaking past the spools. If fluid flows out any of the ports, then the spool is leaking.

When a hyd car jack leaks, and you don't see any fluid, where is it going. You might say past the valve, but really, can the bore and piston not wear and cause a leak down internally, and cause the jack to fail/descend.

I only seek the truth, not BS.

Who has the balls to razor blade their cyl seals, raise the loader and provide us a scientific answer which can be repeated.

So what some of you are saying is that with a perfect spool valve , no leakage, that the loader will never descend with engine on or off with no lever movement.

I may just have to sacrifice one of my cyl for a test.

When I took my loader valve in for a bench test, they said it was good, and did not mentioned any leakage. However after re-installing the loader valve and raising the lift arms, after 12 hours, the lift arms were on the ground. What is the logical answer.

Please don't beat me up and make me eat green bell peppers.

 

[k0ua]

6) Leakage test for the boom cylinders/spool.

Place a load in the bucket that induces a pressure reading in the boom cylinder base end of approximately 1000 psi. Raise to approximately mid-stroke. After a short period of time note the pressure on the rod end side of the boom cylinders. It should be near zero and not increasing. If it is not near zero or is increasing, oil is leaking past one or both of the boom cylinder piston seals and the cylinders need to be repaired or replaced.

If fluid is leaking past the seals, where is it going, and is any parts moving. With the control valve in the neutral position if there is cylinder seal leakage, the fluid goes to the rod side, and out the rod side hose down to the control valve, and if it leaks it goes to the tank.

Would the loader move at all? It depends, if the cylinder seals do not leak, and the valve does not leak (they all do) then no.

If the seals never leak and things don't move, why are people repairing the seals on the loader cyl. I give up

Why even have seals if they can hold a load without them. Because without seals, you would never be able to fill the cap side of the cylinder as it would just to the the rod side, out the port, down the hose to the valve, and immediately to the tank as the valve on the rod side is now open to tank to evacuate the rod side as the cap side fills.

Do you really think they replace all that many valves because of loader leak down? I don't know.

Mysteries of all mysteries, what is causing the leak down? I think most leak down is through the control valve.

When a hyd car jack leaks, and you don't see any fluid, where is it going. You might say past the valve, but really, can the bore and piston not wear and cause a leak down internally, and cause the jack to fail/descend. I am not sure how they are built, I need to see a diagram.

I only seek the truth, not BS. I think we all do.

Who has the balls to razor blade their cyl seals, raise the loader and provide us a scientific answer which can be repeated. Not me!

So what some of you are saying is that with a perfect spool valve , no leakage, that the loader will never descend with engine on or off with no lever movement. I don't see how it can ever descend, because with a perfect spool valve, a perfect Quick connect, and perfect hose, you have what amounts to a plugged port on the rod side. There is now way that fluid could ever leak into the rod side even if there was a leaky cylinder seal, because the rod side is full of fluid also, and it is incompressable. Of course we are assuming the gland seal does not leak too!

I may just have to sacrifice one of my cyl for a test.

When I took my loader valve in for a bench test, they said it was good, and did not mentioned any leakage. However after re-installing the loader valve and raising the lift arms, after 12 hours, the lift arms were on the ground. What is the logical answer. All loader valves leak.. ALL, so why would they mention it?

Please don't beat me up and make me eat green bell peppers.

I would never do that!

 

[LD1]

James did a pretty good job answering. I'll give you answers in my wording.

6) Leakage test for the boom cylinders/spool.

Place a load in the bucket that induces a pressure reading in the boom cylinder base end of approximately 1000 psi. Raise to approximately mid-stroke. After a short period of time note the pressure on the rod end side of the boom cylinders. It should be near zero and not increasing. If it is not near zero or is increasing, oil is leaking past one or both of the boom cylinder piston seals and the cylinders need to be repaired or replaced.

Notice it never said anything about cylinder drifting. The fact that they are going to the trouble of installing gauges instead of simply using the "cylinder drift" method should tell you something.

If fluid is leaking past the seals, where is it going, and is any parts moving.If there is leakage past the seals, the pressure on the rod side and cap side will equalize, but thats about it. if the valve holds, the fluid cannot go anywhere, just equalize pressure

Would the loader move at all?If the valve is good, no.

If the seals never leak and things don't move, why are people repairing the seals on the loader cyl.No one said the seals never leak or go bad. Just that when they do, they wont cause a loader to drift or leak down. I imagine alot of people are repairing them cause of false information of people telling them that is why their loader dont hold.

Why even have seals if they can hold a load without them. Power. If piston seals leaked, allowing system pressure on both ends of the rod, you would loose power. Cause with the valve moved to raise the loader, the situation is no longer a static one as with the valve in neutral. With the spool shifted, the base port is open to power, and the rod side port is open to tank. Therefore fluid can bypass the piston, exit the rod port, and return to tank through the valve. The worse the seals are, the less power you have.

Do you really think they replace all that many valves because of loader leak down?I have no idea. I dont work in a dealer service dept.

Mysteries of all mysteries, what is causing the leak down? Like I said before, it IS possible that there could be spool leakage that only effects the rod side port. But the base side port in the spool seals fine. Think about the fluid flow. Pressure INTO the base end of the cylinder. If seals in cylinder are bad, it can migrate to the rod side of the cylinder (but only if fluid can leave the cylinder somewhere). If it can leave out the rod side port and return through a leaking spool to tank, then there are acctually 2 things wrong. Cylinder seals AND spool. In this case fixing only the cylinder seals would solve the issue. Cause if fluid cannot get past the piston, it cannot leak at the spool. Likewise, fixing the spool would also solve the problem, because regardless of how much oil "can" get past the piston, if it cannot exit the cylinder, it wont move

How many of you really think the problem is the spool leakage.ME

It is not hard to test the spool valve, just remove the IN, OUT, and PB hose hoses with the loader raised, and see if any fluid is leaking past the spools. If fluid flows out any of the ports, then the spool is leaking. Yes, it is easy, but no need to. IF the loader is raised up, and drifts down, and there are NO other external oil leaks, then yes you will get oil out of the valve ports. It HAS to go somewhere for the cylinders to retract. So again, as long as there are no other leaks, it is pointless to do that test.

When a hyd car jack leaks, and you don't see any fluid, where is it going. You might say past the valve, but really, can the bore and piston not wear and cause a leak down internally, and cause the jack to fail/descend.It depends on how the jack is made. I have never tore one apart. IF the rod side is open to tank, then yes a worn piston would cause it to fail.

I only seek the truth, not BS. I dont think anyone is trying to BS you. Just give you the facts.

Who has the balls to razor blade their cyl seals, raise the loader and provide us a scientific answer which can be repeated.Not me. I just have a feeling that doing so, you would still not believe. And wouldnt believe what we are telling you till you do it for yourself. But no need to damage anything. Just remove the seals. That way you can put it back when done with the test. And remember, you must ALSO have a good valve. Lets call the rod side port "A" and base side "B". IF your spool is leaking from "A" port to tank but have good piston seals, you wont drift. IF you have bad piston seals, but a good valve, you also wont drift. It takes BOTH. But it is unlikely that the spool will only leak to tank on the "A" port. Leakage rate and wear should be close to the same for both "A" and "B" port. In which case you will see drift no matter how tight the piston seals are.

So what some of you are saying is that with a perfect spool valve , no leakage, that the loader will never descend with engine on or off with no lever movement. Correct. But no spool will ever be "perfect" An easier test would simply be to unhook the quick couplers from the valve. Or use a ball valve to isolate the cylinder. No matter how bad the piston seals are, If the cylinder is totally isolated so NO oil may exit the cylinder, the cylinder WONT retract no matter how much force is put on it (until it blows up or pops a hose)

I may just have to sacrifice one of my cyl for a test.

When I took my loader valve in for a bench test, they said it was good, and did not mentioned any leakage. However after re-installing the loader valve and raising the lift arms, after 12 hours, the lift arms were on the ground. What is the logical answer. Assuming you arent leaking anywhere? A weeping fitting or gland seal? Was that max height to ground in 12hrs? or just a few feet?

Again, assuming no external leaks, the only thing it can be is the valve. They "tested" it as good, but by what specs? Remember no spool is perfect. So when they tested it, what was the leakage rate and at what pressure? I imagine a loader spool valve has a tighter tolerance for leakage than something like a logsplitter valve. But this is a perfect place to test what we have all been telling you. Right now I imagine you are convinced the valve is good (as tested) and that your cylinder seals are bad. So do this, Raise the loader but not so high that you cannot get a floor jack and some blocking under. Then unhook the quickconnects so the loader isolated from the valve. Come back in 12 hours and you will either fine 1 of 2 things. 1:The loader will be in the same place you left it proving the seals have nothing to do with it. 2. The loader will be on the ground accompanied by oil that has leaked out of the gland seal or a fitting somewhere. If 2 is the case, fix that leak and repeat. To re-install, use the jack to take pressure off the loader so hooking the QC's back up is easy.

Please don't beat me up and make me eat green bell peppers.I hate green peppers so I wouldnt wish that on anyone:laughing:

 

[J_J]

Thanks, I appreciate everyone's response.

 

[TJP89]

Look, the bottom line is, in a perfect system, nothing would move. Who would design a loader that sinks by itself However, the loaders sink. Thus something isn't perfect. I think we've eliminated the cylinder seals, so it's got to be the valves. When the tractor is running, the pump is keeping everything pressurized and where it needs to be. When it's off, there is going to be some leakage through the valve.

 

[LD1]

I think we've eliminated the cylinder seals, so it's got to be the valves.

Now if only we can convince everyone else that.

 

[TJP89]

Now if only we can convince everyone else that.

Yes it took me a second to get that, as gases, which are compressible, are more my thing. Once you're there, it's pretty straight forward, maybe a schematic of the hydraulics of the loader would help.

 

[LD1]

Yes it took me a second to get that, as gases, which are compressible, are more my thing. Once you're there, it's pretty straight forward, maybe a schematic of the hydraulics of the loader would help.

I dont think a schematic would help, but I could be wrong.

It is the fundamental understanding that you cannot shove a cylinder rod into the cylinder bore without displacing the oil somewhere. Once everyone gets on board and can understand that, then perhaps a schematic to show just where that displaced oil goes would be of help. But we have to get over that first step. Too many still believe that the oil can just bypass the piston and stay contained within the cylinder and still allow the cylinder to retract without any oil leaving.

 

[murphy1244]

We are all learning new things so its all good. I have learned a lot from you guys and I appreciate it.