Which item is not a good pump maintenance practice?

Tightening packing glands until they stop leaking is not a good pump maintenance practice because it can lead to excessive wear on both the packing and the shaft. Packing is designed to create a seal that minimizes leakage while allowing for some fluid to escape, which can help keep the packing lubricated and reduce friction. Over-tightening packing glands can cause increased friction, heat buildup, and premature failure of the packing and associated components. Proper maintenance involves ensuring a balance where there is minimal leakage without compromising the integrity of the pump's components. Thus, it is important to adjust packing glands to allow for a slight amount of leakage that will keep the packing lubricated rather than tightening them excessively.