I was getting my 94 Pathfinder back up and running, replacing belts, etc. The brakes had a leak back when it was running, but I never had time to track it down. The leak was small and would need new fluid added every two weeks or so. So we bleed the brakes and everything works fine. We check all the connections, and hoses and nothing is wet. No wetness around any of the calipers either. Then I notice there is fluid leaking out of a hole on the master cylinder. (Attached photo shows were the hole is). So I go looking for a new master cylinder and notice that around half o f the photos I see have that hole totally covered up.
So my question is could a screw have been in that hole and fell out causing this slow leak? Would covering that hole prevent the leak?