To facilitate the removal of old packing and the installation of new, what should be opened?

When addressing the removal of old packing and the installation of new packing in hydraulic systems, opening the bleeder is crucial. The bleeder valve allows trapped air and fluid pressure to escape, which helps relieve tension within the system. This is particularly important because any residual pressure can make it difficult or unsafe to remove components like packing. By venting the system through the bleeder, you create a safer working environment, enabling smoother removal of old packing and more straightforward installation of new packing without the risk of fluid spraying or other hazards. Opening the bleeder ensures that the system is depressurized, facilitating the work at hand and ensuring optimal performance when the system is reassembled.