Time for some hydraulics troubleshooting GC2410

[rjmack]

Well, I guess something had to break sooner or later. :laughing:

have been doing a lot of digging/traveling over the last week. today the bucket curl system gave up the ghost.

bucket will still curl relatively decent, but will not hold. requires constant pressure on the joystick while traveling with or without load.

main boom seems to hold, quick connectors are leaking the way they have from new but nothing unusual.

I'm guessing either both cylinders have failed, or an o-ring in the main valve body has calved.

everything was working fine one trip, next trip major weeping action, stayed the same thereafter.

If anyone has experienced the same thing on theirs, would appreciate hearing about what you found out.

 

[Fiziksgeek]

I think if you curl the bucket and disconnect the hydraulic lines, and the bucket still droops down, then the problem is in the cylinders (assuming the quick disconnects are leaking). If it stays up, then the problem is in the valve.

 

[oldnslo]

I think if you curl the bucket and disconnect the hydraulic lines, and the bucket still droops down, then the problem is in the cylinders (assuming the quick disconnects are leaking). If it stays up, then the problem is in the valve.

Sorry but that only works if you are retracting the cylinders. Reason being that the rod end volume is smaller than the cap end volume.

Since holding the lever in raise keeps it raised I would suspect you blew a cylinder seal.

If you dump the bucket slightly so Just the cutting edge is resting on the ground and then use the hydraulics to lift the front of the tractor do the cylinders stay put or drift? If they drift rapidly then you have a valve issue. If they hold fairly steady you most likely have a cylinder issue.

 

[rjmack]

Sorry but that only works if you are retracting the cylinders. Reason being that the rod end volume is smaller than the cap end volume.

I don't get what you mean, but I'll take your word for it. I really wasn't sure how to proceed, kind of panicking with a day or two before freeze up.

I managed to pretty well finish the job I was doing today, so I'll take a look at it tomorrow morning.

thanks for the replies.

 

[Fiziksgeek]

I'm definitely not the most experienced guy, so Oldnslo is more likely to be correct. Just trying to think through the problem to see if you can isolate the issue. The lift cylinders are under the loader arms, so they lift when extended, but the curl cylinders are in the top, so they retract when curling the bucket. I would have thought that if fluid was leaking past the seal, it would do it regardless of weather you were extended or retracted, but maybe not!

 

[oldnslo]

With a single rod cylinder the rod takes up some of the volume of the cylinder. Since oil does not compress you can in theory remove the seals from piston on a cylinder, completely fill it with oil with the rod extended. Seal both ports. You cannot push the rod in unless there is an external leak.

Mathematical representation using a 2" bore, 1" rod 18" stroke cylinder.

Blind or cap end volume = 56.55 cubic inches

rod end volume = 42.41 cubic inches

The rod takes up 14.14 cubic inches

This why it will not retract unless there is an external leak.

Fully or partially retracted under the same situation you can pull the rod out. Yes it creates a vacuum but it takes a lot of vacuum to hold a loader bucket.

Does this help clear up what is happening?

 

[rjmack]

With a single rod cylinder the rod takes up some of the volume of the cylinder. Since oil does not compress you can in theory remove the seals from piston on a cylinder, completely fill it with oil with the rod extended. Seal both ports. You cannot push the rod in unless there is an external leak.

Mathematical representation using a 2" bore, 1" rod 18" stroke cylinder.

Blind or cap end volume = 56.55 cubic inches

rod end volume = 42.41 cubic inches

The rod takes up 14.14 cubic inches

This why it will not retract unless there is an external leak.

Fully or partially retracted under the same situation you can pull the rod out. Yes it creates a vacuum but it takes a lot of vacuum to hold a loader bucket.

Does this help clear up what is happening?

not sure. wouldn't an o-ring failure in the valve body curl in circuit act the same way? there are separate sections on the spool for curl in and curl out.

the cylinders extend (weep) toward the rod end in a pretty big hurry. I can't hear any sucking sounds that would indicate the cylinder is pulling in air from the end seal, nor am I experiencing any spongy sort of response.

It is rock solid with weight on the cutting edge of the bucket, and that's with the rear of the machine sitting on the backhoe bucket.

do these cylinders have chevron type seals in them, or just a donut squeezed around the piston?

I'm perplexed that it is leaking so quickly in direction but not at all in the other. I get that you can't compress a fluid, but for this to happen basically immediately makes me wonder. the bucket did weep before, but this has taken it to a whole new level.

maybe one cylinder has been bad for some time and the other one just went out?

I checked and rebuild kits are available but not oem cylinders. I bent one of the cylinder rods pretty bad a few years ago, straightened it back out on the machine with a chain and block of wood so I'd probably lean toward replacing the cylinders.

evidently the newer GC loaders have different cylinders on them, does anyone have any insight into this?

I also checked on a rebuild kit for the valve body, and was told there wasn't one so it would basically just be a matter of matching up the o-rings.

 

[oldnslo]

There are no o-rings to leak on valve spools except for the ones to keep the tank line oil from weeping on the ground. Attachment shows a sectional view of a "typical" valve.

As far as seal type. This depends on the cylinder style, some have a simple O-ring and some use chevron seals.

 

[rjmack]

There are no o-rings to leak on valve spools except for the ones to keep the tank line oil from weeping on the ground. Attachment shows a sectional view of a "typical" valve.

As far as seal type. This depends on the cylinder style, some have a simple O-ring and some use chevron seals.

I never realized spool valves had no internal o-rings... man, that is some close tolerance machine work!

sorry about the delay replying, I got dragged away unexpectedly.

seems to be an issue getting replacements from the dealer, maybe I'll start looking for a couple cylinders in the aftermarket.

Thank You.

 

[rjmack]

Sorry but that only works if you are retracting the cylinders. Reason being that the rod end volume is smaller than the cap end volume.

Since holding the lever in raise keeps it raised I would suspect you blew a cylinder seal.

If you dump the bucket slightly so Just the cutting edge is resting on the ground and then use the hydraulics to lift the front of the tractor do the cylinders stay put or drift? If they drift rapidly then you have a valve issue. If they hold fairly steady you most likely have a cylinder issue.

well Oldnslo, you were right on the money. :thumbsup:

finally got the seal kits ordered and installed, and the problem is solved.

it's interesting that it was actually just one cylinder that had catastrophic failure, and it was the wipers, not the o-ring that calved, but I guess there is enough volume in one cylinder for pretty well all the oil from the rod side of both cylinders. I'm guessing the other cylinder was leaking as there was visible wear on the rod o-rings also.

btw, these cylinders are from a 2009 model DL100, so the design might be the same as the gc2300 and earlier gc2400 series. there are serial numbers stamped into the cylinders to order the kits by. this is the earlier design. kits were $55.00 CAD each as opposed to $500.00+ CAD for new cylinders. first cylinder took 4 hours to do, second took 1/2 an hour. it's not so bad once you figure out what's what. the cylinder cap end inner rod seal is a bugger to change though, better practice up on your patience before trying that. :laughing:

gc241 dl1 loader problem - YouTube

gc241 curl cyl rebuild - YouTube