Greased bearings applications have no protection to prevent over greasing. The recommended greasing procedures generally are not followed An oil mist system would be the best if you could solve the problem of leakage of the mist to atmosphere and the resultant fugitive emissions problems. If you open the bearing case of your spare power ends you will find that the inside of the case is often badly rusted. The manufacturer should have provided some type of a protective coating to prevent this problem. They contain strong detergents and can remove many of these protective coatings.
Many liquids contain solids.
Centrifugal force will throw these solids against the inner wall of the volute and out this recirculation line. They will then enter into the stuffing box at high velocity, causing premature seal failure. In most cases the problem can be solved by eliminating this line and connecting a new line from the bottom of the stuffing box to the suction side of the pump. It could flash in the stuffing box. This is the reason we see so many bent and broken snap rings.