1984 John Deere 850 Hydraulic issue

[Ken Haney]

I have a John Deere 850 (1984) with a Yanmar Motor. The issue is with the hydraulic lift. After running the tractor for a while, and when it is good and hot, I raise the lift (bush hog most frequently) and it refuses to go back down. I can park the tractor over night and usually by the next day the lift is working fine. The fluid level is showing full. Any ideas as to what I need to be looking for?
Thanks for you input.
Ken

 

[J_J]

Check your descent/rate of drop knob.

 

[Ken Haney]

Thanks J_J, I have adjusted both and nothing is happening. Usually if it hangs I can move the drop knob and it will do just that....drop, but this time it is stuck in the up position and has been for 4 days. I worked with it yesterday thinking it might go down, but with no results.

 

[J_J]

That threaded might be a solid rod or there might be several parts under the threaded rod, such as a spring and plunger, etc,

If there is some debris or rust blocking the small port, the release of fluid will be slow or no release.

You might try raising the 3pt and secure the arms up, and remove the threaded rod. Place 3pt lever in neutral.

Put something over the hole to catch anything that might come out, and release the 3pt arms. It might blow out any trash or other parts in there.

The knob/threaded rod, must be functional for the fluid to escape the cyl. This knob is also used for transport to keep the attachment up, and secure.

 

[Leejohn]

On my 950 there was a small rod under the seat toward the front and it pointed side to side, it was painted red. If you move it to to one side it would stop the 3 point. If I remember right I ran with it pointing up. It all most looks like a roll pin. Maybe that well help if yours has it.

 

[Ken Haney]

Thanks JJ, I am going to tear into the tractor this weekend, and that is what I have concluded, there must be some trash or rust preventing the rod from releasing. And Leejohn, I am going to look for that rod tonight.
Ken