Greetings--

Just ran into this for the first time--

PacFab 2hp pump- round case on front of motor. Appears to run fine-- pressure OK, normal noise.

Until......

I reduce the backpressure by opening the fountian valve. This valve diverts the water from the pool's jets to a fountian. When I reduce the backpressure on the pump even by just a little, the pump begins to make a "grinding" noise.

I didn't notice this last year-- only recently.

I took the pump cover off-- nothing stuck in the impeller. It rotates freely.

Suggestions ??