Hello, Greetings from South Alabama 2012 650k, 5100hrs, new pump, control valve, fluids, etc. I've owned the machine for 2 years. It's had this condition since I picked it up. During operation, if an obstacle becomes lodged under the blade with leverage to push upward, the blade will rise without operator input. I sent the machine to the dealer, and during shop testing, with the machine running and the blade control lever centered in neutral, we attached a crane and found the blade could be lifted approximately 2-3" upward. However, if the blade was first pushed down and then raised back up about 2", it could not be forced upward. Deere tested a similar 650K and reported the same condition as “normal,” but I believe this indicates a malfunction in the blade holding/check system since the blade should remain hydraulically locked in neutral and resist external force. Again, we already replaced the pump and control valve with no change to this condition. Has anyone else experienced this or found a fix? Thanks in advance for any assistance!
Have you replaced any hoses or repacked cylinders in the blade lift circuit recently? I've had hoses/cylinders with a small amount of trapped air cause similar unusual behavior. It doesn't take much and it can be a bear to get out if you aren't intentional about it.
We've replaced all the hoses up front going to the cylinders and both cylinders that lift the blade were resealed along with several others. Is there a special procedure for bleeding the air out of the circuit?
Don't know much about john deeres But this made me think of Quick drop valves
This isn't specific to your application, but there was a lot of good discussion in this thread: HeavyEquipmentForums Short version: Take each line off at the cylinder, hold valve until oil comes out, then reconnect. Same with cylinders, I like to prefill them after rebuilding to get as much air out as possible. Once you have the cylinders and lines mostly full of oil: with oil at operating temp, take each cylinder loose (no load), orient them so ports are facing up, move piston to center of stroke, cycle back and forth starting just a 1/4" each direction, slowly moving further and further, until you're at full stroke.
Machine serial number? Did it always do this or is this something that just started happening?
What exactly did you replace when you say "control valve"? This sounds like a weak circuit relief to me.
I can say 100% there is a fault on the valve bank... Can not tell u what it is but there´s a fault in there, unless JD wants to reinvent the wheel. To solve that matter u need to lay hands on the hydraulic circuit description, and ID what does what... Usually when one opens a spool fluid will not go anywhere if the line is over system pressure, and below rated relief pressure wich ussually is very high. Same happens when fluid is forced by a ram to flow through the spool , actually it can only flow through the system relief pressure valve, and not the spool. But blade lift cylinders usually are fitted with "float features" and "dead drop" wich is pretty much same valve as the float, and very important Tilt proportional valve, and in the top of that, system relief pressure valve. This can be separate valves or a single unit in the main bank. one thing is, that all this are actuated by the spool valves. Get the valve bank out and inspect it, it might be only a piece of rubber or plastic bloking some port. good luck
My 2015 650K I believe is electric over hydraulic. Ser: 1T0650KXJFF285035 Could a over pressure in the circuit be allowed to relieve via the computer allowing the blade to raise?
It was my first guess as well.