What must be done to a new or rebuilt pump before installation?

Filling the case with fluid before installation is essential because hydraulic pumps rely on the presence of fluid to operate effectively. By ensuring that the pump is filled with the correct hydraulic fluid, it helps to minimize the risk of damaging the pump during startup due to lack of lubrication or proper functionality. If the pump is not adequately filled, it may lead to cavitation, which can cause significant damage by creating air pockets that reduce efficiency and harm internal components.

This step also prepares the pump for normal operation, allowing for a smoother startup and reducing the chances of air being trapped within the system. Proper filling is crucial for ensuring that the hydraulic system can build the necessary pressure and properly circulate fluid once the pump is operational.