Hydraulic weirdness on 8n

[john_fulmer]

So, my 8n that i'm slowly (and unwillingly) rebuilding has a hydraulic issue where in position control mode and with a significant load on it (in this case, a brush hog), unless you move the control very slowly, the hydraulic go all the way to the top, and then drops down to the position it SHOULD be. Until it gets to the top, the control does nothing until after the drop.

A little background:

The hydraulics on this 8n didn't work well when I got it. That is, position control pretty much had an 'up' and a 'down' and it wouldn't hold a load in the up position.

Took the hydro apart, replaced the arm piston to a new version, disassembled the control assembly, replaced the pin, straightened the control arm (how DO they get bent like that?), made a jig, adjusted it, cleaned it all out with diesel, put it all together, and it acted like it worked fine.

Until I put a load on it. Then it acted as above. I know my next step is to pull the hydraulic pump, since something acts like it's sticking in the control valves, but does anyone have ideas on what is actually causing this?

Note: I actually pulled it apart twice and readjusted... same issues.
Thanks

jf

 

[john_fulmer]

Update: I pulled the check plate off the side, and when it rises to the top, the inside control arm stays open until the arms hits the top and then 'snaps' into place where it should be. I think I reassembled something wrong. Time to pull it apart again.

 

[JMOR]

(quoted from post at 21:04:09 10/26/23)
Update: I pulled the check plate off the side, and when it rises to the top, the inside control arm stays open until the arms hits the top and then 'snaps' into place where it should be. I think I reassembled something wrong. Time to pull it apart again.

......in addition to your checking assy, be sure both intake and exhaust calves are free to move and not sticking. When lift gets to top (piston part way out of cylinder), piston hits a pin and this is a pretty good force on control arm.

 

[TheOldHokie]

(quoted from post at 11:26:13 10/27/23) ..in addition to your checking assy, be sure both intake and exhaust calves are free to move and not sticking. When lift gets to top (piston part way out of cylinder), piston hits a pin and this is a pretty good force on control arm.

You just saved me from msking a big mistake. I have a cylinder here that I was going to sleeve as an experiment and my plan was to cut that tapered "tail" off the cylinder. Good thing I have procrastinated on this project....

TOH

 

[JMOR]

You are more than welcome. I try to help as much as I can, but lately, it seems I spend too much effort trying to manage the mis-information that those wanting to help, but really can't, put out here. So many seem to think that whatever they have experienced,one time in their life, applies universally to every tractor & every situation in the whole world! Some even start with, "I have never touched a Ford,but here is your solution". :roll: