One of the most common reasons for a sprinkler to start leaking between the pop-up riser assembly and the body cap while it is in operation is because the riser seal is worn or there is debris between the seal and the riser
Part # 181500
Removing the old seal
Unscrew the body cap and remove the internal assembly.
Place the base of the riser on a solid surface and grip the spring and riser body firmly.
With your other hand, snap off the body cap. With your palm on top of the logo cap, pull up with your fingers.
While still gripping the spring and body, remove the rubber seal. When you remove the seal, the tension in the spring will be released.
Remove the plastic spring seat.
Installing the new seal
With the base of the riser on a solid surface, push the retraction spring down below the nozzle turret and hold it there.
Drop the rigid-plastic spring seat onto the riser, grooved side down, so it rests on the spring.
Carefully work the new flexible rubber seal, flat side up, onto the nozzle turret, and then down onto the riser body. Take special care not to twist or deform the flexible seal as you work it down over the gap between nozzle turret and riser shaft.
Snap the body cap onto the body. The cap will slide down freely once past the ring at the top of the nozzle turret.
Carefully release your grip on the spring.
Exercise the assembly several times (push the cap down and let it be pushed back up) to ensure the parts are seated and do not stick.
Reinstall the assembly in the sprinkler body, screwing the cap on tightly with your hand. Be sure no threads can be felt under the body cap—if you can feel the threads, the seal is not seated properly
Note: The new riser seal incorporates improvements that increase the durability and life of service.
Before turning on the sprinkler to check for leaks, necessary adjustments and proper retraction, you should check the final installation height to determine if the sprinkler is set at grade.