Hydraulic Lift Is Dropping and Hiccuping

[jtmcdon]

I have a 1958 Ford 861 Diesel and I am having an issue with the hydraulic lift. This just started this year. With a 5 foot rotary attached I can raise the cutter all the way to the top but then it immediately drops down to a little above half way. At that height it will also slowly start to hiccup. However, when I lower the cutter down to a few inches above ground to cut the pasture I don't notice it hiccuping but it will drop all the way to the ground after a period of time.

Any help is appreciated.

Thanks. Tom

 

[Tx Jim]

Normally 3 pt hiccuping is caused from a worn rockshaft piston seal.

 

[k0ua]

Yes, by definition "hiccuping" is because of an internal leak. As the piston settles down, the position control feedback mechanism applies more fluid to the piston which raises it again, which starts the whole sequence of leak-down, raise, leak-down cycle. The whole idea of position control is to maintain a 3pt position when the valve or piston leaks. And they ALL leak. It is just a matter of degree. Yours leaks a LOT. So much that the position control is constantly trying to keep the 3pt up and the leak is constantly trying to make it fall.

 

[jtmcdon]

James,

I appreciate the reply. I have seen kits but I'm just not sure which one I need for my specific tractor and will the kit include everything I need. I'm pretty good at replacing the obvious but don't have the knowledge to isolate a single cause of the problem. Also, when I remove the top cover, which I understand is under the seat is there a possibility of springs or other parts falling out of place.

After replacing all of the piece parts will I need to bleed the system at hydraulic pump?

Thanks.
Tom