All Hydraulics leak down

[J_J]

regularjay,

Just about all loader valves leak to some degree. The leakage is based on the specs that the valve is made. If the spools, and the valve body are made from different material, the expansion rate may be different. I don't think that anyone has done a consumers report on hydraulic valves, to give us an idea which valves are best, better, or just plain junk.

When the bucket leaked down with the hose disconnected, did the amount of fluid match what would have been in the cylinder? That would be a true test of a leaking valve. Do a 12 hr test with bucket up and tilted up.

If your loader valve is using the PB port, the leakage could be leaking out the PB port,or the valve out port. To check something like this, raise and tilt the bucket up, and shut off engine, then remove the hoses from the out port, and the PB port. As the lift arms. and bucket drop, you should see the results of a leaking valve. It would be hard to imagine two or 4 cylinders leaking, unless really worn out. The cylinders should leak down a little bit until the pressure equalizes, and if the valve spools are good, then they should hold in place.


A cylinder test can be performed by pressurized one side of the cylinder with fluid , and collecting the fluid from the other port to see if the fluid is bypassing the piston o-rings. Just about all hydraulic shops have the ability to test all your hydraulic items, cylinders, valves, relief valves, priority valves. etc.

Did you do your test while the fluid was cold, or hot. In theory, more load /pressure, should cause an increase in leakage, however, pressure/heat may cause a better seal.



Some valves are so bad, that one can watch the bucket drop. I have had my valves tested, and they tested good as for as the relief activated, and I don't know if they did a leakage test, as that would take some time for a non pressure test. My loader arms will drop from fully raised to full down in about 15 hours. As long as the machine will lift the rated load, I will have to accept that , as it would be difficult to be searching for that zero leak valve, but I could use a gate valve to shut off the cylinders, and keep the load up .

 

[regularjay]

I talked with my local Kubota dealer Friday and learned that a "seal kit" is available for this valve. The parts guy showed me the diagram of the valve with what looked to be just a bunch of O-rings for $65.00 He was unable or unwilling to speculate if replacing the o rings in my valve would improve my situation. I would really like to fix this for around sixty bucks instead of a couple hundred for a new valve. I have no external leaks at all so it would seem that fluid has to be "bypassing" inside the valve. Is it feasible to think new seals might cure this? I need this fixed but dont want to be further in the hole for a fix that isnt.

I did not disconnect a hose, the "out" port of the loader valve has a hose that goes into a "T" fitting on top of the tranny with a cap on one end of the "T". I removed the cap, and with the empty bucket elevated I could see a very small amount of fluid coming in through the "return" hose. The amount of fluid did not seem like near enough to account for the leakage but I don't know where else it could be going. The PB port I believe powers the 3-point which leaks down way faster than the bucket! I have ordered a replacement "O-ring" for the 3-pt cylinder and really hope that fixes that. A 12 hour test would waste 11:50 as my bucket even when empty leaks down in under 10 minutes.

 

[J_J]

Did you put the hose from the loader in a container, and collect the fluid for the time it took the loader to drop to the ground. If so, then you should have collected the amount of fluid in the cylinders. The only other place the fluid can go is from one side of the cylinder to the other side of the cylinder. You can rebuild the valve, but if the spools are worn, there is nothing that will fix that, even with new spools. The precision of these spools are not what you think. One vendor makes the valve body, and it might be made from one grade of steel, and the spool might be made from another grade of steel.and maybe another vendor makes the spools, and they only have to meet specs with a small variation. If a new valve leaks when tested, they remove the spools and reach in the bucket and install another one until it meets specs. So, even a new spool might not help, because the valve body of the spool might be worn. That is why some manufactures have posted that some leakage is acceptable, even to stating the amount of drops of fluid within a certain time frame. You can certainly rebuild the valve, and it just might fix the problem.

Just because the loader will leak down, does not necessarily mean the loader is not working right. In a static situation, like a loader fully raises, and engine off, there is a certain amount of force on some of the cylinders, caused by the down weight of the the loader. This pressure will vary based on the weight of an empty bucket and a full bucket, etc. Now, with the engine running and the pump building pressure, the pressure might help the seals do a better job at sealing by forcing the material to expand and do the job of sealing. However, if the seals or o-rings are weak ,torn, deformed, fluid will bypass and leak down, and you may not even see the leak on the outside.

I forgot to ask if you collected all fluid going back to tank. Normally fluid from the cylinders exit the valve via the out port, but when a PB setup is used, if the valve is leaking trough the PB port, that fluid is going back to the rear remotes and then to tank, therefour the question about did you collect all the fluid going back to reservoir?

 

[GE222]

JJ, Thanks for all the info. I have been reading all of the posts in detail for the original post. I have a Kubota B7200 that barely even lifts its 3-point. All I have done so far is to change the fluid, and clean the intake screen. My next step was to put a gauge in the system.

At engine idle, the 3-point won't lift, but at a higher RPM, it will go up but very very slowly. Once up it will hold pressure, and stay up. Unfortunately due to more pressing issues,I haven't had much of a chance to spend much time on this tractor, but lately, it is becoming more of a priority.

 

[relaqbr]

regularjay,

Just about all loader valves leak to some degree. The leakage is based on the specs that the valve is made. If the spools, and the valve body are made from different material, the expansion rate may be different. I don't think that anyone has done a consumers report on hydraulic valves, to give us an idea which valves are best, better, or just plain junk.<snip> My loader arms will drop from fully raised to full down in about 15 hours. As long as the machine will lift the rated load, I will have to accept that , as it would be difficult to be searching for that zero leak valve, but I could use a gate valve to shut off the cylinders, and keep the load up .

I am a newbie here and I have a question. I have a new scut which I am really happy owning but the fel drifts down just a little. So being a very **** person I want no down drift . However, I am realistic on occasion and so my question. How much is too much down drift. I appreciate JJ's comment on there being no consumers reports on hydraulics. And was wondering about anecdotal evidence from the group. I would also guess that the load and thus the diameter of the cylinders would come into play. So is 200lb in a fel with two 2inch cylinders that drifts down 5inchs in 24H too much? Great group!

 

[J_J]

That is probably less than most of us have . As long it will lift the advertised load, I would not worry about it.

 

[regularjay]

I appreciate all the interest/responses regarding my problem. I have purchased new "o" rings for my 3 point cylinder as well as the rebuild kit for my loader valve. Once I've installed everything I'll update this post with the results.

Jay

 

[soulasphil]

I used to have a 1960 Massey Ferguson 35 with a Massey loader (single action hydraulics) and it could be left with the loader up for several months, it would stay exactly as you left it. I now have a brand new John Deere 3520 and the picture is quite different. I use a hedge trimmer with 3 cylinders and a hydraulic motor which will drift down overnight ( have found it in awkward positions in the morning several times). The 60 D deck will come down in a matter of hours and the 300 CX loader will drift down to the ground in under a week. My dealer says it's quite normal, nothing to worry about. I much prefered the way the Massey behaved !

 

[J_J]

I appreciate all the interest/responses regarding my problem. I have purchased new "o" rings for my 3 point cylinder as well as the rebuild kit for my loader valve. Once I've installed everything I'll update this post with the results.

Jay

Everyone can appreciate your interest in a leak free valve, but you know the old saying, if it ain't broke, don't fix it. By tearing the valve down, you might make it worse. If you ordered the FEL o-ring kit, save it for when it really does leak, unless you really want the practice, taking something apart. Some valves do not even have o-rings, and rely on the manufactures tolerance for a good fit. If you ever get a valve that is leak free, then it probably has been tested over and over, in all temperatures, etc. Even the leak you think is in the 3pt cyl, might be in the 3pt valve. There are ways to test all hydraulics on the tractor, but is for the most part not practical.

I don't think they will ever get to the point of stating we have a maintenance free tractor.

Like some else said they could lift a bucket in the air, and it would stay there for months. Perhaps good valves, perhaps check valves.

Most people don't leave their buckets up anyway, primarily for safety reasons. Just let a kid jump up on your tractor and touch that lever, and his little brother is playing around the tractor, you will probably never leave the bucket up ever again.

 

[soulasphil]

The way you can store your tractor varies considerably. In my case, there's no way I can get it inside my 19th century granite shed unless the loader is up and the bucket down. Changing from the Massey to the leaking Deere means I now have to rest the loader on one of the cider barrels. Lowering the loader on the Massey implied first to change the position of two valves before the main control acted on lhe loader instead of the 3 pt hitch or trailer. Mice, bats or children have never managed to do that in the fourteen years I kept the Massey.