3 point hydraulic drifting on yanmar ex2900

[alltherage]

I have a finish mower on the back right now and I've noticed that every minute or 2 the hydraulics kick on and raise it. It's drifting down. This is during idle and I've never had this problem before. If I shut the tractor down I can hear the mower creak as it slowlyyyy sinks. The last 2 years I've been using a rather large snowblower in wintertime but it weighs less than the 3 point is rated for. 100 to 200 pounds less. I only use it on my driveway and it's not very often. Is there an adjustment or have i ruined a seal or something? This is a 2011 with 180 hours on it. The hydraulics have been used very little, just finish mower in the summer and blower in the winter. sporadic loader work but essentially this tractor has been babied. thanks for any help

 

[Fallon]

If the 3pt is drifting down enough to cause the feedback lever to raise it back up frequently, something is leaking. Hydraulic cylinder packings (seals) or something in the valve assembly are the most likely culprits.

 

[Fallon]

As fast as the weight on your snowblower... is that just under capacity with or without several hundred lbs of snow & ice caked on it?

Probably didn't make much difference as most 3pts will lift more than they are rated to. Part of that rating is keeping the front end on the ground.

 

[alltherage]

the blower is 869 and the mower is 610. the 3 point is rated for 1100. here are some things i noticed...it only seems to do it if the lift arms are well over center or all the way up. it doesn't seem to do it if the lift arms are a bit over center or below. Also, it doesn't matter if i raise the rpms or if i'm at idle. I also checked to verify with a measuring device that it was actually sinking, and it was. It's doing it every 40 seconds or so. Like I said, if the arms are raised up only a little bit, so the mower is off the ground completely, it doesn't do it from what i've seen. ideas? and thanks so far

 

[Fallon]

RPMs will make your pump pump more fluid. But pumping fluid isn't your problem, higher RPM & more flow will just make hydraulics run faster. Your problem is the 3pt cylinders or valves are leaking a lot. The feedback mechanism notices this at a certain point & opens the valve to raise the cylinders back up. That feedback mechanism is working properly & is how the height lever can set the height properly rather than raising or lowering the 3pt an randomish amount like tapping on the loader lever.