Bad Valve Symptoms To Look For:
1. Leaks around the valve.
Leaks are a pretty obvious symptom of a broken sprinkler valve. Leaking around the valve could be caused by a number of issues. Look closely at where the water is leaking from. Is it coming from around the solenoid? Is the anti-siphon part of the valve the source of the leak? Or is the sprinkler valve leaking around the housing of the valve? Getting to the root of the problem is the first step so that you can more accurately weigh the cost of replacing a valve vs repairing it
2. Low or no water to the sprinkler heads.
If the sprinkler heads seem to be getting very little or no water but the valve is clearly on this could be a bad valve symptom. Sprinkler pressure problems could be caused by the sprinkler valve not allowing enough flow through the valve.
The first thing to do is to try to isolate the source of the problem. Make sure the valve is turned on all the way first. Next, check to see if only one valve is affected or if all the valves have the same problem. If all but one valve is working properly then it is likely that all of the valves are getting sufficient water and it is just the one valve that needs to be worked on. When the problem is isolated to one valve it could mean that the diaphragm inside the valve has gone bad.
If all of the sprinkler valves are not getting enough or any water then the problem is most likely not the valves. The source of the problem can be at the main sprinkler shut off or at the pressure vacuum breaker.
3. Sprinkler valve is not turning on.
If the sprinkler valve will not turn on with the timer it can be a bad valve symptom but it can also be just a wiring problem. Try turning the sprinkler valve on manually to isolate an electrical issue.
If the valve works when turned on manually the next step is to find out if it is the wires or the solenoid that is not working properly. The first thing to do is to check the wires. Make sure there is good contact where the wires connect. Check that there are no cuts or breaks in the wires. If the wires look fine it could be the solenoid. The solenoid can be easily replaced, but with the cheaper sprinkler valves you may find it almost more cost effective to just replace the valve rather then do a few repairs, especially if the valve is already a few years old. The commercial or heavy duty valves are usually worth rebuilding a number of times, but you pay for it upfront.
4. Leak at the sprinkler furthest from the valve.
This is one of the bad valve symptoms that is easy to miss. When there is standing water or leaking water at the sprinkler furthest from the sprinkler valves it could be the sprinkler head, but it could also be that the corresponding valve. Standing water is a sign that the valve is not shutting off completely. There can be several causes for a sprinkler valve that doesn’t turn off properly. If this is a new problem check for debris in the valve that can be causing it to stay open. If cleaning doesn’t solve the problem it could be that the valve is broken and once again you must decide to replace or repair it. If the problem is not new it could be that the valve was installed backwards. Check the valve to ensure that the direction of flow is pointing the right way.