...the hydraulic pump that is a new, rebuilt from the factory, fresh out of the box model makes a very loud knocking noise, and the hydraulics don't work.
Is this a sure sign that the hydraulic pump is no good or can faulty valves in the back cause the pump to behave this way? Or is there air in the pump? I am reluctant to run the tractor at all with the pump acting this way for fear of damage to the cam or crank.
I am faced with an $800 rebuilt piston pump, $310 rebuilt vane pump, or used piston pump if I can find one. I am trying to see all the possibilities before I make yet another large purchase.
BTW... I am using 134 hydraulic fluid from New Holland.