Turbo, The pressure loss in an automatic solenoid valve is the energy source used by the valve to open and close the valve. If the valve doesn't have enough pressure loss it will not have the energy needed to close by itself. Most electric irrigation valve are "pilot operated". The design is made so that water pressure and a spring work together to keep the valve closed. The solenoid opens a small "pilot" passage to relieve the water pressure in an area that is keeping the valve closed allowing the spring to open the valve. There for the cracked top is acting like the pilot valve and relieving the static pressure that keeps the valve closed. Replace the cracked portion or the whole valve(less problematic). Also check your pressure. The reason for the crack may be water-hammer from having too high a pressure in your system. Do you have your irrigation off a faucet(house pressure side) or Teed from your house water mainline before the house water pressure regulator(high pressure side)? Aloha

You might be able to install arresters on your line if you share the same water lines with that neighbor and it will help some. Basically the pressure travels through the pipe till it finds a place to go, and if it travels up towards you it could be why you hear the loud noise. I had a toilet that when the fill valve stopped I would get a knock that sounded like it was coming from the main shutoff valve mutiple rooms away. I installed a water hammer arrester there and have not heard the noise since. I do know you are 'supposed' to install these close to the problem fixture, but I didnt have access to the line inside the wall by that toilet so I just installed it where it was knocking and it worked. I would try to locate where the noise is coming from and install them there on your lines

From one of the links; System is making a loud noise when the zones are starting, then the noise goes away until the next station/zone starts or only on specific zones. The cause for this is when a zone starts where water has drained out of the sprinkler heads the force of the water flow does not have any resistance and it will cause the pipes to make noise until the zone is under pressure. Also it could be caused by water turbulence in the interior plumbing of the home. Here's an explanation on how that may occur: When a irrigation system is connected to the house it is done by tapping into a water line (usually close to the meter) the tap is usually a Tee type fitting. Well when the irrigation is running it pulls water from both sides of the Tee fitting. We have found that if you place a check valve on the side of the Tee fitting furthest away from the meter so the water flows through the meter then out to the irrigation it will solve majority of problems associated with noisy pipes. By doing this your are preventing the irrigation system from pulling water from your house pipes which is usually the cause of the noise. If the noise is not that bad and only happens on a few zones then you may want to strategically place check valves on the zones that have elevation change to reduce drainage after that station runs. Steady noise during the entire time the system runs, sounds like a thumping noise. Your water meter is making the noise and you need to have it replaced. What do I do if the water department says it is not the meter? Tell them you want a new meter or a larger meter, my experience is that if you are hearing a constant noise during the entire time the system is running that it is the meter and take a firm stance to have it replaced. I have been told we need a new meter becuase a hot tub was replaced after the meter was installed.

IF you find the city to be a fault and they refuse to do something, take it to legal. About the only way you can 'make' them do something. Other ideas, I wonder if your PRV is faulty, I don't think it should allow pressure to go so high? Another way to help with the symptoms is to install a large expansion tank in the main line which acts as a buffer. It acts as a collecting tank and it has a bladder to control pressure.