Cavitation in pumps is caused by excessively low pressure at the pump inlet. A blockage or restriction such as a clogged filter or part-closed valve mounted on the inlet to the pump can cause it. It can also happen when the pump has to source its water supply from a sump in...
The HPD catch can has a metal bowl on the bottom which you are supposed to unscrew. There is no chance in the world I can get this undone without removing the catch can. If you have small hands or a filter wrench you can undo it, but the much easier way to empty the can is to...