Pump and prime issues

Need some advice. Last year some friends came over and used our pool (inground with hayward max flo pump). When they left they turned the valve off that allows water to flow to the pump( thinking it was for the slide). A day and a half later when I returned I noticed what had happend. The pump had ran the entire time with no water circulation. I opened the valve and to my surprise it began pumping the water. The problem I am having is that when the pump is turned off it loses prime. We like to keep ours on a timer so that it will turn off at night and then start back up in the mornings. After this episode, it will not begin pumping again without me pouring water into it. Can this be repaired by replacing some seals or something? Any help greatly appreciated!

It sounds like the pump got hot; and one of the PVC adapters (possibly discharge side) got soft and sagged, and now, when the pumps off, air leaks in, causing you to lose prime.

Could be the suction side, too, but if so you probably have air leaking in while the pump is running. If it's the discharge side, you may have a small water leak when the pump is running.

PoolDoc

Just to elaborate a little more on what Ben said, regular PVC will soften well before the boiling point of water. CPVC is used for hot water plumbing but usually not for pool plumbing. Since you had water in the pump chamber but it wasn't moving, all the energy was going into heating the water and thus softened the PVC joints. Had you run with the pump chamber empty then the water seal would be cooked and you would have a leak when it started pumping. Run the pump, prime it, get a full charge of water and shut off the pump. See how long it takes for the pump basket to lose water. Then smear vaseline around the PVC joints and run the test again. All it takes is a tiny air leak to cause problems. Vaseline isn't messy and can be wiped off pretty easily using alcohol. The other possibility is the chamber itself warped and maybe the lid isn't sealing very well. Give the whole pump and basket area a good visual looking for cracks.
Al

Thanks, Al.

Ben / PoolDoc