Sucking air on on suction side of pump

[yargh]

Hi All,
I was hoping for some advice before I start replacing stuff. I am getting air on the suction side of my plumbing and I think it's the 3 way Jandy valve that controls flow between skimmer and the drain. When I have it full open it doesn't appear that much air gets pulled into the system. However if I close it in either direction I get more air in the line (especially if I close the skimmer and pull only from the main drain). When pump is off I don't appear to have any leaks, and the water level doesn't appear to drop any more than usual (I don't have an autofill).

If I'm right what should I look at replacing? The entire valve, or does typically a rebuild + O-rings typically work?

 

[chiefwej]

If it is the valve a rebuild should take care of it. When looking for a suction leak, you can often isolate and confirm it with some plastic wrap.

 

[duraleigh]

As you pull from either skimmer or main drain, you are applying additional suction (restriction) to the pump intake.

Check the pump 0 ring first. That varying suction can cause the o ring to leak when suction is high and stop leaking when suction is low (when the jandy is pulling from both sources)