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Totally Off Topic: Need Some Farmers Help


SuiteSuccess

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I have a Kubota B7200 with a front end loader. The hydraulic valve that operates the front bucket is "sticking" when trying to lower the bucket arm making it very jumpy going down. All other functions are normal. Any hints before I tear into the valve or have to purchase a new one? I have tried lubricant etc with no luck. Seems to be internal to the valve.

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I've used a product called "Seafoam". It's an additive that cleans gunk and gummy deposits. I know it can be added to gasoline and diesel fuel. Check the label and see if it would be OK to add an ounce to the hydraulic fluid. If you can, the Seafoam might clean your hydraulic system.

 

http://hildstrom.com/projects/seafoam/

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SeaFoam is made to be burned off. I wouldn't put it into a hydraulic system. It does sound like an O-ring has unseated or some dirt has gotten into the valve body itself. Is there a filter on the system anywhere like our steering systems on the trucks? I'm thinking that it's a regular push/pull plunger type valve with several O-rings. Not hard to rebuild with the right kit.

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Leave the bucket a couple feet in the air when you tear into the valve, it will make a great youtube video!

 

Seriously get everything down and solidly resting on the ground to avoid the joy of getting sprayed with oil and launching the small bits into the weeds which makes finding them for reassembly so much fun.

 

Might be worth flushing and refilling the system if it is older, a new filter if you have one is a great idea too.

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Try this:

 

https://parts.cat.com/en/catcorp/1u-9891-1u-9891

 

It is an additive from Cat to eliminate a sticking cylinder.

 

It has worked on everything we have put it in with "sticky" parts that have a build up on them.....

 

If that doesn't work, you will need to tear into the valve body to see what is going on.

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Carl;

Try to avoid pulling the valve spool out of the valve body if you can. Look at the centering spring and make sure it is not broken or collapsed. Change the fluid filter if there is a separate system. I don't recommend additives such as rust inhibitors or anti foaming agents for hydraulic oil. Should already be in the oil. Open the old filter and see how much crud is in it. Silt is normal, chunks aren't. If you do pull the valve spool out, make sure that you mark it in some indelible fashion so you can reinstall it EXACTLY as it was removed. Keep the sandpaper, emery cloth, whetstones, and files in the tool box. They just make a "leaking by" situation worse. Do not smooth the sharp edges of the spool lands. Exception is for a gouge in the spool with a matching gouge in the valve body. If the gouge is only part way across the land and there is a raised sharp edge on the edge of the gouge, you might get by with very carefully stoning the edge of the gouge. Remember that the spools are hand fit (even the cheap ones) unless they are the low pressure o-ring type, so anything you do that removes material from either the spool or the valve body increases the "gap" between the spool and the valve body and, consequently, increases the potential for leaking past the internal seals.

 

Paul

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No additives. Like Prego, it's already in there.

 

It sounds like you have a sticking spool valve, as Paul suggests. My guess is that you have an o-ring that's got a tear in it, with a sliver getting caught in the lands. I'm not that familiar with Kubota valves, but it can't be that difficult. The fact that it's happening when you're trying to lower the unit leads me to believe it has nothing to do with a clogged filter.

 

Like Stanley said, be sure ALL pressure is bled off before any dis-assembly.

 

Can you post a pic of the offending valve?

 

One other thought, you might ask the service manager at your Kubota dealer. It might be a common problem.

Yet another idea: does the valve stick when the tractor is not running? Try just moving the lever without starting. If it sticks, you need to service the valve. I'm gonna go out on a limb and suggest it will involve no more than a pin and a packing nut to access the spool valve.

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Thanks to everyone. Rick will try to get a pic this afternoon. Unfortunately the Kubota people here just want to sell new parts. Every time I've been in with a question always get the " just need to replace it" talk. And Kubota parts are pricey.

GeorgiaHybrid, my tractor has a common sump apparently with the hydrostatic transmission so the Cat product wouldn't work but thank you for the help.

Stan: very aware about releasing all pressure on system. Changed out a leaking quick connect without all the pressure off. Lucky I was in the grass or my garage would have been a mess.

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Leave the bucket a couple feet in the air when you tear into the valve, it will make a great youtube video!

 

Seriously get everything down and solidly resting on the ground to avoid the joy of getting sprayed with oil and launching the small bits into the weeds which makes finding them for reassembly so much fun.

 

Might be worth flushing and refilling the system if it is older, a new filter if you have one is a great idea too.

 

Ha, ha, ha !!!!!!!!!! That one caught me off guard Stanley. Definitely youtube is the place to watch that stuff.

 

But I would change the hoses between the curl and the lift and see if the valve still sticks to make sure there is nothing down stream causing an issue.

 

Then rest everything on the ground and look into the valve for a faulty back up ring or galling on the spool. Kubota is good at keeping things clean and is a good brand of tractor. However, a small particle of something can still get past and end up between the spool and bore, or between the o-ring and it's back up ring.

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Look at the springs that center the valve spool they should be on the ends of the valve spool usually opposite of the handle. The O-rings and wipers to seal the valve spool should be on the ends of the spool, the internal seals are the grooves around the spool and close tolerances, no rubber parts, it's called a Labrith seal, ck spelling. If the valve operates smoothly with the handle your problem is somewhere else, either in the cylinders or lines, most likely a hose delaminating internally and acting like a flapper valve.

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The Sea Foam that was mentioned earlier was the Sea Foam Trans Tune which is made for Transmissions and hydraulic systems. It is harder to find than the Sea Foam for engines. I have used the Trans Tune in hydraulic systems to eliminate "stiction" and it has worked. It is not totally magic, so it won't cure everything but it is often worth a try....just my opinion, though. Charlie

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Suite: We really need to know what Rick says above. There is a major difference between a valve that "feels" stiff, so its hard to feather the motion, and the actual movement that jumps when you activate the valve.

If its the loader itself that jumps, you may have a bad hydraulic coupler. See if you reverse hoses to isolate the problem. I also know of a loader that jumped because of a sticky check valve on the lower function (designed to hold the loader from sinking...it worked a bit too well!)

A stiff lever on the other hand...go ahead and pull apart the valve, clean thoroughly, and replace the orings. Make sure any "indent" ball/spring assemblies are loose. A very common problem is a frozen indent ball. Do not let them talk you into a whole new valve body for this unless its leaking. See if you can't find a exploded parts diagram...ask your dealer for a print "so you can see what part you will need!" :D

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Here are some pics of my valve. My loader is a Woods not a Kubota so sorry for the mistake. The sticking seems to be in the valve itself. As I push the stick up you can feel a catch then it will " break" and the bucket will jump. The tractor is Kubota

 

Make of the loader doesn't matter now. You've isolated the problem to one spool valve. These things are crazy simple. Take your time and pull it apart, being careful that nothing falls into the grass. A catch pan is good, a towel is better (parts won't bounce).

 

I'm betting on an o-ring with a bad spot hanging in the bore. I'll go out further on that limb and predict you only need one o-ring, but if they offer a seal kit for each valve, get it. Can't be more than a few parts in the entire kit. Look up your model # loader and see if they have an online parts catalog. Kits are normally at the bottom of the page.

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It's too bad we aren't about 200 miles closer. You have some interesting projects. I just have maintenance.

 

For instance, I drained about 9 gallons of 3 y/o gas out of the generator tank today. Doesn't smell that bad. I'll run it through my only gas tractor. At 66 years old, it won't care. Now I need to get 5 gallons of av gas to put in the genny tank and run it for a bit.

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It's too bad we aren't about 200 miles closer. You have some interesting projects. I just have maintenance.

 

For instance, I drained about 9 gallons of 3 y/o gas out of the generator tank today. Doesn't smell that bad. I'll run it through my only gas tractor. At 66 years old, it won't care. Now I need to get 5 gallons of av gas to put in the genny tank and run it for a bit.

 

Just curious, but what is the advantage (other than higher octane) to using av gas?

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