older yanmar trackhoe

[redoakrowdy]

Why does my main boom go down before it goes up when I pull back the main boom lever. Is it air in the system and how would I purge it? Thanks.

 

[Gary Fowler]

I don't know the reason but my Yanmar 4220D tractor with FEL did the same thing with the FEL after it was used for a few years. It must be a problem in the joy stick valve. I never fixed mine and sold it as is.

 

[winston1]

I'll start by saying I am no hydraulic guru and only stating here what I found from a little googling. It seems the load checks might be the cause of the dropping. Also seems the springs might be the weak link. I am attaching a prince parts drawing just so you you might see just what these parts are. http://www.princehyd.com/Portals/0/valves/LvManual.pdf