Bucket Cyls not holding when off

[N1ST]

If I start my tractor after being cold for a while and lift the FEL, the bucket just rolls down with gravity (the bucket cyls do not hold it in position). If I then use the control to curl the bucket, it will then stay in the postion I leave it while the tractor is running. I never noticed this before, so I think it's something that started recently. It's a newish tractor and I don't see any fluid leaking. I also don't know yet how long I have to leave the tractor off before it acts this way.

What would make the bucket cylinders not hold their position?

 

[MFRED]

Try disconnecting the quick connects with it in the air. Be careful as they will be hard to get back on after and you may need a jack to relive the pressure. If while disconnected it still droops, its in the cylinders, if not its in the valve. Remember a certain amount of leakage is allowed.

 

[Soundguy]

As mrfred says.. the cyls may be leaking across internally, and thus you will not see an external leak.. same with the spool valve.. etc.

soundguy

 

[N1ST]

I think I understand. But, is "leaking across internally" a spool valve issue? What can happen to cause internal leaking start all of the sudden (on a newish tractor)? Could being a little low on fluid contribute to this?

 

[Willis Fecon Bushhogging]

If I start my tractor after being cold for a while and lift the FEL, the bucket just rolls down with gravity (the bucket cyls do not hold it in position). If I then use the control to curl the bucket, it will then stay in the postion I leave it while the tractor is running. I never noticed this before, so I think it's something that started recently. It's a newish tractor and I don't see any fluid leaking. I also don't know yet how long I have to leave the tractor off before it acts this way.

What would make the bucket cylinders not hold their position?

This is what I did to check my FEL droping. I wouldnt advise it, unless you are sure how to do it.I Loaded the bucket, Shut the engine off. I then disconnected the down line on one of the cylinders (Be careful, it may have pressure)
When you get the hose off, I guess there is a little leakage allowed, but if its steady running out of the cylinder fitting, its probrably bad. Now hook up the hose and try the other cylinder.
Use extreme caution and safe methods, if you try this. Of course, you could take both cylinders off and have them checked by a hydraulic shop. If one of them is bypassing, you have to rebuild both of them, or it puts a strain on the other one, causing it to leak. I learned this the hard way.

Another way, if you are using the FEL alot, stop after 10 minutes and check to see, what cylinder is the warmest, then check it again after another 10 minutes. The hottest one, probrably is bypassing. If you dont have a use for it now, just load the bucket with anything and raise and lower kinda fast and get someone to keep checking to see, which one is the hottest.

Another way, and it doesnt always work. Look at the tip of the bucket and see if you can tell what side starts moving first, its probrably that cylinder bypassing.
It sounds like a seal has cracked or rolled in the cylinder, or a broke oring in the spool valve.
Good Luck and always be safe with hydraulics

 

[john_bud]

I think I understand. But, is "leaking across internally" a spool valve issue? What can happen to cause internal leaking start all of the sudden (on a newish tractor)? Could being a little low on fluid contribute to this?

The seals in the cylinder piston can leak. You may have "cheap China" cylinders with the wrong material in the seals. That will allow them to deteriorate quickly. Or good cylinders with correct seals and some contamination in the oil.

95% of the time it's the cylinder and not the control. That's good as it's pretty cheap to fix a cylinder but you basically have to toss the control.

You may also have air in the cylinders from running it low on fluid. Warm everyting up. Extend the cylinders all the way and hold the control in that position for 5 seconds. Then retract all the way and hold for 5 seconds. Repeat that process for 5 cycles. Check the fluid level in the res and make sure it's up correctly. Test the drop time. (I doubt this is it....buy may as well check).

The way to check for internal leaks (aside from the methods above which are also good) is to extend the cylinders all the way to the stops. Then disconnect the hose from both cylinders that causes them to retract. Then use the control to extend the cylinder, building pressure in the cylinder. (the pressure relief valve will keep everything okey-dokey). You shouldn't get much flow out of the open port, if you do, it's the internal cylinder seals leaking.


For comparison, my 2000 kubota will hold the loader arm up and bucket up for 2 months with it only dropping 2 feet. (Had to store the loader over the mower this winter).

jb

 

[N1ST]

Thanks for all the suggestions everyone. I'm inexperienced working with cyls, so I won't try the risky ideas.

From what I understand, MF had a bad batch of bucket cyls. Not sure what the story was. One had a tiny slow drip - it took me weeks to determine if it was really leaking. Once this droopy bucket started appearing, I figured I needed to get it fixed (under warranty). I don't know if it was bypassing.

JB: Let me get some more detail on this approach...
I top off resevoir.
I extend the bucket cyls fully.
Turn off tractor.
Detatch the lower hose on one side and put in milk jug.
Turn on tractor.
Try to extend further (won't be able to of course).
See if fluid came out of hose.

...is this correct?

Can a cylinder be detached from the bucket and be extended and retracted for testing, or would the cyl be damaged, having no resistance?

When a pressure relief valve releases, it's all internal, yes - so there is no leak onto the ground like there would be when a furnace relief valve opens?

 

[rback33]

This is how I would do it.

Warm up the oil in the tractor. The valve should be warm to the touch, but not hot at all. Put some weight of some kind in the bucket. By rule you would want 500 PSI in the system at rest, but it's obvious that you will not have a pressure gauge. You could use a scoop of dirt, sacks of quikrete.. anything. Set the bucket level with the bucket about hood high so that part of the cylinders are extended. Disconnect all quick couplers from the valve. To be very specific, mark the cylinders before disconnecting and check mark them again after say 10 minutes. You can then provide the data to someone with the manufacturer and he can tell you what the fluid displacement was and whether or not it is in spec. If the loader does NOT move when disconnect then it is a valve problem. The same principal applies to the leak down of the valve, you just leave it all connected. Unhooking HOSES is an unnecessary and dangerous method in my professional opinion.

 

[Wayne County Hose]

Ummmm, professional what?
1. Cylinder drift tests are done with no load, not full load or half load. The load of the equipment the cylinder is holding as per the data plate as dealer delivered is the load anyone in the know would look for.
2. Disconnect qd's under pressure? I would bet a weeks pay he doesn't have this style. Disconnecting under a load is not safe and is also extremely difficult and may result in unnecessary injury.
3. 10 minute drift test? Most I've seen are 15 minutes. Could be 10 for these cylinders.

If I were to do a cylinder drift test, I would first contact the manufacturer for the specific details. But, I wouldn't bother as his issue is not cylinder drift while under use. Here is what I would do.
You need 4 steel plugs and 2 steel caps for the bucket cylinder hose connections. Lower your FEL to the ground, shut the engine. Move the valves thru their functions to relieve any pressure from the system. The bucket cylinders should be half retracted or more, if not, place blocks under the bucket so that they are in this position at rest with all pressure relieved. Remove the hoses from the bucket cylinders. As you remove them, install the steel plugs into the hose fittings. As you remove the rod side hoses, install the steel caps on the cylinder fittings. On the rod side only, very important. When done, start the engine. Lift the FEL off the ground a foot or so. Place drip pans under the uncapped ends of the cylinders to catch any oil. Now, just monitor over 4 hours or so. If you notice the cylinders drifting immediately and can see the movement, the piston seals are sauce. If the cylinders have moved all the way out within the 4 hours, the piston seals are sauce. Another way to test was described above. Leave the rod end hoses installed, remove the base end hoses. Start the engine and hold lever retracted for about 15 seconds. If oil comes out of the base end cylinder port, your piston seals are sauce. As with anything, work safe work smart. 10 fingers into the job, 10 fingers out.

 

[MFRED]

I'd bet a years pay says if he's doing it on that GC2310 in his sig, he's got quick disconnects. I'd probably bet another years pay says its the cylinders. Most quick disconnects can be coupled and released under pressure. A MF GC series tractor doesn't connect under pressure but it will release. A pressure release is needed to recouple either by releasing the pressure on the loader or you can wiggle the valve while holding pressure on the coupler. I guess you could pinch a finger, but I wouldn't worry too much about serious injury. Cracking lines & Pluging lines without the propper plugs, thats dangerous. I think we all know high pressure oil spray can puncture skin. That,s why man invented cardboard to check for external leaks.