SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Alright, I am pulling my hair out troubleshooting a hydraulic irrigation problem, and I need help! We are working on a 8 zone hydraulic system. There are 4 valves that are sticking on all of the time. As soon as you pressurize the mainline, everything is good (no cut hydraulic tubes). However as soon as you turn that zone on, either manually or at the controller, it won't shut back off again. We've bled the air out of the tubes, cycled them, waited 15-20 minutes for them to shut off, with no luck. It is not the controller, because we just switched over to electric / hydraulic actuators with a new electric controller, and it is not the diaphrams in the valves, we tried replacing those too. Two of the zones that are sticking on have two valves connected together, I was unaware that you could do this, however I don't think that this is the problem, since it has worked in the past. Is there anything else I am overlooking. We also talked about going completely electric, however because of the landscape, this would be extremely difficult. Thanks!