Tractor question

[Finster101]

I have a Kubota L3000DT with an LB400 loader on the front. I recently had to replace a couple of the hydraulic lines. I have topped off the fluid. The problem is it just does not seem to have the same power it did before. Is there a bleeding process I need to do? There are no physical problems with the lines or hoses that I can see. It works okay, it just doesn't seem to have the ooomph that it used to. Any help would be greatly appreciated.

James

[oneokie]

Did you replace with the same size line?

Which function is different? The boom lift or the bucket tilt?

A simple way to eliminate any trapped air in the cylinders or lines is to cycle the boom through the full range from max. height to min. height (even if it lifts the front of the tractor off the gound) Have the transmission in neutral when doing this.

During one of these cycles, cycle the bucket through its full range of motion while the boom is at its max. height.

[Finster101]

Thanks, I will give that a try. Hose is the same size. I replaced the corresponding hose on the other side just to keep them the same, plus it just needed changed. I have a hydraulic shop that rebuilds the hoses for me and the reuse the threaded fittings so ID has to be the same as what came off. I'm an ASE master tech, but I work on more Cadillacs than Kubotas.
Thanks again,

James

[geargnasher]

Sounds like you have a bigger air bubble in one cylinder than the other, have you tried bleeding the hoses? Sometimes air gets trapped in those double-acting cylinders and due to the positioning doesn't work it's way out very well. A big air pocket on one side vs. the other will sometimes soak up the power and make the carriage act like it's only operating with the power on one cylinder, which in effect it is. That's a good way to twist a carriage, too, if you put too much load on it.

Gear

[ss40_70]

one question comes to mind , did you run the hydraulic system out of oil ? depending on pump type cavitation can ruin a pump in very short order , this is doubtfull in your case though as i would imagine the hydraulic system is run off a gear pump and not a impeller type

[Frosty Boolit]

Blow by on piston o-ring?

[Finster101]

Thanks for the suggestions. I have not had a chance to try them yet. Hopefully this weekend.

James

[P.K.]

Sounds like you have a bigger air bubble in one cylinder than the other, have you tried bleeding the hoses? Sometimes air gets trapped in those double-acting cylinders and due to the positioning doesn't work it's way out very well. A big air pocket on one side vs. the other will sometimes soak up the power and make the carriage act like it's only operating with the power on one cylinder, which in effect it is. That's a good way to twist a carriage, too, if you put too much load on it.

Gear

You hit it. Problem is air. You have it in the system. Pull the sub-plate and repace the o-rings. If the sub-plate is connected to two individual systems, and one or the other fail in their job, it's a fairly easy fix. Isolate the fail and move on with the working side.

If both fail it's the sub plate.....

[Mk42gunner]

Sounds like you have a bigger air bubble in one cylinder than the other, have you tried bleeding the hoses? Sometimes air gets trapped in those double-acting cylinders and due to the positioning doesn't work it's way out very well. A big air pocket on one side vs. the other will sometimes soak up the power and make the carriage act like it's only operating with the power on one cylinder, which in effect it is. That's a good way to twist a carriage, too, if you put too much load on it.Gear

Very true, I managed to twist and bend just about everything on the homemade loader that is on my WD by not getting all the air out of the "new" cylinders I put on it. One of these days I will buy some steel and fix it....

Robert