I've had the same problem on my LNC360 with the pump cycling on for an instant, about every 20-30 seconds.  I have the same type of pump shown in Clark's attachment (series 108 OilDyne pump).  I tore it down and replaced all the internal O rings, reinstalled it and it continued to do the same thing.  I then disconnected the extend side of each gear actuator and plugged it and then turned power on in an attempt to isolate a leaking cylinder.  But that didn't help either.  Now I didn't check the door actuators which are also T'd off the same lines.  I'd say the actuators and pump are about 5 years old.  Anyone have any other suggestions for eliminating this hydraulic cycling??''

Steve,

 

The door actuators are the easiest to rebuild as the pipe/flare connectors do not have to be removed.  Are you sure the dump valve is not leaking?  Sometimes it is useful to isolate the problem to a specific "wheel well" first by cutting off the distribution at the cross where it supplies fluid to both door and gear actuator - unfortunately these crosses are often located under the console just behind the main spar.

 

Good Luck.