JD 3pt won't lift.

[SBMF 2015]

I have a JD 4640. The 3pt goes up and down as it should with only the quick hitch on it. I just bought a Blu-jet 3 shank, 3pt, sub soiler. Hooked it up today and the 3pt will only lift it a couple of inches off the ground.
I checked the hydraulic oil, it's in the safe spot on the dip stick. I tried adjusting the draft control, it made no difference.
Any suggestions? Thanks.

 

[Atimm693]

There is a big nut under the rockshaft lever on the housing. Make sure that is tight. Could also be the rockshaft piston seal going bad. If you shut the tractor off, how long does the 3pt stay up?

 

[SBMF 2015]

There is a big nut under the rockshaft lever on the housing. Make sure that is tight. Could also be the rockshaft piston seal going bad. If you shut the tractor off, how long does the 3pt stay up?

The 3pt goes down in about 5minutes or less after you shut the tractor off, but it only goes down roughly half way. Then stays there. I always lower it all the way before I start the tractor so the starter doesn't have to pump up the 3pt also. Once the tractor starts I raise the 3pt and it stays up all day until you shut the tractor off.
I'll check that nut tomorrow.
Thanks.

 

[kenny thomas]

Probably not it but unhook the top link and see if it will raise up. If so its the adjustment on the top link binds it.