I know the solution may not be difficult for the pros, but I'd like to learn too. I've been chasing this for two weeks
a few weeks ago, the pool started losing water. One of the return lines to the pool snapped at the pool wall and I lost a significant amount of water. The water level then proceeded to dip below the skimmers and then I sucked air into the system. This caused prime to be lost and had the pump running dry for a few hours.
The leak has been fixed but now my pump will not hold prime overnight. I have to manually prime it from the spa every morning.
Things that I've done to the equipment.
1. noticed that pump was "burping" water every time I turned off the pump. So I went ahead and replaced the o-ring. light lube and tightened the thumbscrews. I did notice that the o-ring seemed to be thicker than the one I replaced, but both pool stores said that I had the correct one for the Hayward Super II pump. even after replacing the o-ring, I still get a "burp" when shutting off the pump. This is my prime suspect for the current air leak.
2. A small amount of water was puddling at the threaded output pipe of the pump. So I removed the pipe, added more teflon tape and all seemed good. After a few days, there was still some water weeping out. Quick, go to trouble free pool forums. So I removed the pipe again, wrapped another turn or two of tape and added some oatley joint compound. Seems to have fixed the problem.
3. opened both check valves and removed any debris that may have collected, lubed and replaced. Both of them never leaked any water, so I have no reason to believe that they are the source of the air leak.
4. hand checked the pump drain, no water and no loose screw. did nothing to this.
1. If I prime the system, shut off them pump and turn my jandy valve to the spa. All of the skimmers and drain will hold water behind the valve.
So in the morning, I'll have the pump prime itself from the spa, and then I'll switch the valve to the pool. No water bubbles at all on the valve switch.
2. Once the pump is primed, there is never any bubbles coming through check valve #1.
3. There is no water leaking anywhere that I can detect.
4. I can see a churning of water through the pump basket lid.
5. Last night after I shut off the pump, I watched and listened to see where the water was going, after about 5 minutes check valve #1 started losing water while check valve #2 still stayed full. Overnight, both the check valves would eventually drain.
6. After careful inspection of the pump body and lid, I see no evidence of cracking or warping. There is some deposits here and there but nothing in the area of the o-ring and lid seating area.
The air leak is somewhere between the Jandy valve and the second check valve. My guess is the pump lid, but I don't see anything that drastically wrong with it. My second guess is the difference in thickness of the o-ring that I replaced. Not knowing the equipment well, I'm taking the pool stores advice that I've got the correct one. The reason why I question this, is that when I turn the thumbscrews on the lid,
I don't have that feeling that I'm getting a great seal. This may be the case or me wishing that it's the trouble spot.
So what am I missing that's causing an air leak? My next move may be to buy a new pump lid. ugh!