Suction Leak Causes Pump to Run Dry

[mwagner]

I have a 30,000 gallon in-ground. In order to maintain my prime, when I shut off my pump I close the multiport valve for the inlet that connects the skimmer line and main drain into the pump. Otherwise if the pump is off for several hours, I will lose my prime - this is the reason I cannot use my timer to operate the pump. By mistake, my pump came on when the valve was in this position and ran dry for several hours. It generated enough heat to warp the pump basket slightly.

The issue I have now is that the pump will work but when I attempt to prime the pump the skimmer side will continuously take water and never raise the water level in the basket area. This is not true of the main drain side. If I change the multiport setting to close the inlet from the skimmer, I am able to prime and raise the water level. But whenever a portion of the skimmer inlet is open I can never raise the water level. It just keeps flowing toward the pool. And I am getting air into the system that I have to bleed.

What does this mean? A leak somewhere? What is the best approach to fixing it? How could it have happened? Any help is appreciated. Thanks.