Water pump bearing and plunger grease

[Bryce C]

Apologies I don't have a pic of the internals. But this electric 500 psi Pumptec water pump has a cavity where the bearing interfaces with the plunger. I just rebuilt the pump and it was working fine for a few weeks but is now knocking. I wonder if I may of not greased the bearing/plunger area properly. Can I just use a high quality bearing grease and pack that cavity with it? I used a small packet of grease that came with the rebuild kit and I wonder if that is the issue...

 

[scotty747]

The knocking might be air being sucked in and cavitating. Easier to suck air than water. Make sure there is nothing loose sucking air.