JD 400x Loader Problem

[Smokerich]

Loader bucket continues to tilt down with the control in the neutral position whether the engine is on or off.
Tried:
1. Isolated each bucket cylinder and the buck still tilts.
2. Put rebuild kits in both cylinders, no change.
3. Disconnected both quick disconnects for the buckets, no change.
4. Connected hoses, but reversed -- no change

 

[jinman]

I think there's a good chance your rebuild kit is failing. Retract the curl cylinders all the way up, disconnect retract hoses on both cylinders and put plugs in the ports. Then, lift the loader and see if the bucket droops. If it does, it can only be an internal leak.

 

[Smokerich]

Thank you jinman. That was done. Just got the 2 new rebuild kits from JD. Is the failure rate on those high?

 

[kennyd]

Thank you jinman. That was done. Just got the 2 new rebuild kits from JD. Is the failure rate on those high?

No, not at all. Either the bore of the cylinder is scored, or you nicked a seal when installing the rod. Since the cylinders are plumbed in parallel, only one needs to be bad/leaking to give you trouble.

 

[jinman]

As Kenny suggested, a scored cylinder or damaged seal is probably the culprit and probably only on one cylinder. I'd test each cylinder to see if I couldn't ID the leaking one and just redo that cylinder. Save the spare kit for the next time.

 

[Smokerich]

Checked all the rods, etc. Everything looks in perfect conditions. Tractor only has 250 hours on it. Presently replacing all the o-rings on the hydralic lines. Everyone is pretty stumped.

 

[oldnslo]

Loader bucket continues to tilt down with the control in the neutral position whether the engine is on or off.
Tried:
1. Isolated each bucket cylinder and the bucket still tilts.

How did you isolate the cylinders?
Did you physically disconnect the lines at the rod end and plug them?
Did you isolate the blind end hoses also?

Without seperating the hoses on both ends it would be difficult to tell which cylinder is leaking.

Are the cylinders still removed from the FEL? If yes can you safely apply some pressure to the rod end and check for leaks out the blind end port? This would be the direction of leakage for the bucket to drop.

 

[kennyd]

Here is a test:

Extend cylinder all the way, then remove the hoses on the rod end. Now activate joystick like you are trying to extend cylinder further, check for fluid coming out of the open port.

You can then reverse the procedure and see if the seals hold in the other direction.

In a "perfect" cylinder, no fluid would come out of the open port.