I have a John Deree 5310 from the year 2000. The lift arms lift slowly and are very weak. I have changed the filter and fluid and cleaned the collection grid. if you rev the engine the arms go up. without any attached implement they lift at a normal rate but you can stop them by hand. What could be the problem? What else can I check?
Thank you for reading.
My first suggestion is that you purchase a Technical Manual, as there are a number of tests provided to help determine the problem. URL to buy one from JD provided, the manual is TM1716.
Is this something that has just started, if so, did something happen before? Do you have a charger, how is it working? If you have problems, the problem could be the pump.
Just cycle the valve about 10 times to expel the air. . Do you have air bubbles in the tank? Low pressure could occur if a relief is stuck open. To test the pump, you would need a flow meter and a valve to control the flow.
If the pump is fine and the pump is spinning, then that hydraulic fluid is going somewhere.