JD790/419 Loader drifting down

[txhawg]

Jim,

Is there a procedure you used to trace it to an internal cylinder leak?

 

[Jim_Fisher]

txhawg,

</font><font color="blue" class="small">( Is there a procedure you used to trace it to an internal cylinder leak? )</font>


This is how Deere suggests that you diagnose the problem:

Step Five
If the rod movement exceeds the maximum allowable travel listed in the charts below, determine if the SCV or the cylinder is leaking excessively by:

Stroke the valve to extend the cylinder to full stroke.

CAUTION: To avoid possible injury, support the implement before hose removal. Unexpected movement of the implement could occur and result in serious injury, if the wrong hose is disconnected. Make sure the return line is the one being removed. This is the line at the cylinder's rod end when the cylinder is extended. Avoid oil penetration injury when observing for cylinder leakage.

Remove the return hose from the cylinder.

Stroke the valve in the extend direction again.

If oil comes out of the disconnected cylinder fitting, the cylinder is leaking.

If oil does not come out of the disconnected cylinder fitting, the valve is leaking.

When mine went bad, I just switched the lines from boom to curl. Nothing changed. Since the other circuit didn't leak down, I figured that it had to be one of the cylinders.

 

[txhawg]

Jim,

Thanks for the info. Was it easy to rebuild the cylinder? I am assuming JD sells a kit for that? Would somebody not familiar with hydraulics be able to do it?

 

[Jim_Fisher]

txhawg,

</font><font color="blue" class="small">( Was it easy to rebuild the cylinder? I am assuming JD sells a kit for that? Would somebody not familiar with hydraulics be able to do it? )</font>

It was easy once I figured out how to get the cylinder apart. There is a small oblong slot near the front of the cylinder which is probably filled with soft putty. You have to remove the putty, bend the retainer wire so that it comes out through the slot, and turn the cylinder cap with a pipewrench (there is a hole for a spanner, but I doubt that the spanner would be strong enough). As you turn the cap, the retainer wire will be pushed out. Best to do this with the cylinder still on the loader.

Deere sells the kits and the retainer. I prefer to rebuild both cylinders, since they work together and wear together.

You might want to take them to a local hydraulics shop if you aren't comfortable doing the job yourself.