hydraulic bleeding down unless full pedal engagement

[Josh Frye]

Hi. Im new on here and i have a Bobcat 722 Skid steer that runs great and i have changed wheel seals and bearings and the valve body and done a full service. Im not really seeing any leaks anywhere, but when I lift the bucket and do not do full engagement of the pedal it goes straight down... not sure what is going on seeing how i replaced the valves with new OEM ones and its still doing the same thing. please any help would be great!

 

[funwithfuel]

You likely have a bad piston seal in one or both cylinders. I would start by removing and repacking the one that gets warm first while working.

 

[Josh Frye]

Really? I guess I thought that would be more of the bleeding down when holding a position, but seemed odd it would go down when doing small adjustment up and when doing more heavy adjustments with the lift it works ok. thanks for the quick reply! appreciate it!

 

[funwithfuel]

So it holds firm when you release the control? Is that what you're saying?

 

[Josh Frye]

Well there bleed down when lifted and its pretty fast pressure sure I need to rebuild both cylinders, but my big issue when i apply the pedal to make smaller movements it acts like its in float and drops the bucket to the ground fast even when going up. If I apply full pedal then it will go up but then will drop down slightly when reached desired height then over time bleed all the way down. Sorry having trouble describing the issue I'm having in a message haha. Thanks for the patience! I do believe the lift cylinders do need rebuilt. Im just wondering if there is a valve that may not be working properly and needs replaced or some check valve of some sort. Outside of the Valve body unit and cylinders is there anything else that would cause an issue like this?

 

[funwithfuel]

Do you have an option spool associated with the levers or pedals that may be sticking? Do you have a return to dig function? Not likely with a skidder but who knows. It sounds like a load check or load holding valve fault but you state you've replaced the main control.

 

[Josh Frye]

I replaced the whole valve assembly and there was no change. this is exactly what i got. It was actually hard to find haha

 

[Josh Frye]

the hydraulics are pedal not levers and there isn't a return to dig function. It does bleed down when the lift cylinders are in the air but its slow unlike when you do a partial pedal to lift, up too half engagement, but after half engagement of the pedal it will rise. When you raise it to desired level and let go of pedal it will then drop the bucket a couple inches and hold/slowly bleed down over time.

 

[funwithfuel]

I would look in the cylinder, I'm thinking loose piston to rod or failed o-ring between piston and rod.

 

[Josh Frye]

Ok Thanks! I'll look into that and get back with you guys. May be a little bit, but I'll try to update on if it fixed it or not.

 

[DJZ001]

I’m having the same issue with a mustang mtl25 still can’t figure it out but I haven’t pulled rams apart yet