Howdy!
I have a Challenger 1&1/2HP, pieced a repaired over the last 25+ years. The pump has run dry a couple of times this winter and spring. The basket was hot but nothing appeared to be warped. The pool does not have a main drain (prior owner plugged), therefore the skimmer is the only source of water intake and prone to clogging.

Water: I told chemistry is good, but have had chronic issues maintaining enough chlorine to keep the water from turning green. During this time I've been dogged with pool circulation and filtering issues.

The pump has been priming then quickly (about 30 seconds) losing vacuum with the water level inside the trap dropping quickly. while this is happening the pump is loudly cavitating and struggling to prime itself. Then it finally catches up only to quickly develop another bubble and frustratingly drop out again only to repeat this again and again.

As you can see there is a constant bubble under the clean out cap. This morning I checked the seal of the Jandy valve on the intake side and the o-ring appeared to be good. I then unscrewed the outlet pipe from the pump, cleaned off a lot of residual sealant, cleaned male and female threads and applied plumber's tape to the pipe's male threads. Applied sealant to the lip of the pumps outlet port. Then slowly screwed this joint back together and smoothed the pressed sealant from the joint.

Over the last several years a leak has developed behind the pipe linking the pump and sand filter. Could this leak at the impeller housing be causing air to be sucked in as well causing cavitation inside the housing, loss of vacuum, dropping of water level inside trap and my frustration too???

A person familiar with the pool thinks the pipe attachment to the skimmer has detached and a cavity has formed around that open joint. This might explain the symptoms, but I do not get root material or dirty water and the above steps seem to have decreased the severity of the problem. Although, the leak is still there, the bubble is persistent and cavitation is still audible. Hope that all makes sense.