I have a 3720 (2013) with cab and the lift arms no longer raise or lower.
I think its a hydraulic problem as I have removed the rockshaft control valve cover and control valve, and with the tractor running no oil is flowing?
Where you feeding the driver with the 3rd SCV? I wonder if it's stuck on, like maybe the solenoid is stuck and blocking the flow to the the rock shaft valve. Is the engine laboring at all like the system is in relief?
So when you removed the driver you connected the lines back together????
If not the the path was completed through the open center valve on the driver, and now the path is open and your system is in relief when the machine is running. You risk at a minimum overheating the oil, or at the worst damaging your implement pump.
As I wrote before, we need details, specific ones on what happened before things stopped working, each post I draw a little new small tidbit of info out of you.
So to get the post driver to work properly it required a direct feed, I removed the SCV and connected the driver directly, see image
The post driver and the lift arms worked perfectly until I disconnected and un hitched the driver.
With the SCV still removed (effectively I now have an open path) from that point on the rockshaft wouldn't lift.
I feel you have probably solved my problem in that I need to replace the SCV in order to close the loop/path.
I think you need to brush up on your basic understanding of hydraulics. :good2: It would seem you don't have a complete path right now. So essentially your pump is deadheaded causing your relief valve to lift. This will in short order overheat the oil and cause a lot of damage.
Your tractor has on open center system which means there is a constant flow of oil running through it. That path must be maintained, the oil has to go somehwere. Your picture shows no jumper hose. No oil flow....
The reason your stuff worked with the driver installed is it completed the path and oil flowed on to the rockshaft.
Make a jumper hose from P, pressure, to PB, Power Beyond. Return doesn't get anything in this case. :good2:
Reinstall that 3rd SCV as it was then get the PB kit or make it yourself with a few hoses and large couplers, there is one tube you can remove in the rear to access the supply of oil. I hope you didn't run the machine much like that?