lawn sprinkler that will not shut off completely it trickles from a few heads?

Answer 1

First, make sure your sprinkler heads are not downhill from the valve. If they are, what you are experiencing may be the residual water flow coming downhill even after the zone valve is closed. If this is the case, the water should stop trickling shortly after the zone valve closes. If this is a problem, you should replace the heads with the kind that have check valves installed in them- these prevent water from flowing when there is little or no pressure in the pipe.

If the head or heads are not downhill from the valve, check the zone valve. Unscrew the solenoid and check for debris around the bottom part of the solenoid and in the area where the solenoid screws in. There is a small hole there that needs to be free of dirt and debris. If this checks out take the top off of the valve and check the diaphragm for holes, wear or debris. If there is a hole or excessive wear, replace the diaphragm. If there is dirt or debris, wash the diaphragm. Also look for rocks within the valve body housing. Worst case scenerio, you may have to get in there and replace the whole valve.

Answer 2

If you want to disable only one head in your system, you'll have to cap it off. It's probably 3/4" PVC so all you need to do is get a 3/4" riser (but check it first because it could be 1/2"), unscrew your sprinkler head, and replace with the riser and a cap. Easy fix.

Answer 3

Sounds like you might have dirt or some other obstruction in the valve. If you can get to them, try removing the solenoid and cleaning things out in there.