I have an ASV 4500 skid loader starts off running fine the Boom arm goes up and down very easy the lever control moves easy as well. after about an hour the boom will not go down very easy. I have to push very hard on the lever which is very stiff to get the boom to go down any thoughts on what could be causing this problem. After it sits for a few hours it runs fine again for about another hour.
Might have more responses if posted in the skid steers, but I would think that heat is causing the spool valve to bind. I would be tempted to removing the valve and open it up
Thanks for the info. Will repost and check that.
If the valve spool is getting pushed in during that function, then look at the other end of the spool. Typically there's a round diecast cover on the other end that has a tiny hole for a vent. If there's oil wet around that hole, then take that cover off and replace the o-ring, that cover is filling up with oil and not allowing the valve to move all the way.