My pump has always had a slight suction leak at the pump basket lid, as evidenced by bubbles in the pump basket (until the pump primes), squirts from the basket lid when the pump shuts off, and water loss in the pump basket when the pump is not running. The leak has not been bad enough to prevent the pump from priming, provided the pipes are relatively full. However, I occasionally have to take the basket lid off and use a hose to add water to fill the basket. The real problem is that the lid is not the original lid and doesn't fit exactly right, but apparently well enough to create a close to airtight seal on the gasket. The pump is so old that all I can tell what model it is, which is why I never replaced the lid. I've tried various things to seal the lid, but this week, when I finally thought I had it sealed for sure, suddenly the pump stopped moving any water at all. I thought the impeller might have been obstructed, but I confirmed that was not the case by removing the back cover and spinning it manually with a screwdriver. After another adjustment on the basket lid, the pump started to move water again, but only very slowly. The pump basket doesn't fill and I still see bubbles in the pump basket as the water passes through, which would indicate that there is still a suction leak. However, when the pump is turned off, water doesn't spit anymore and the water level doesn't go down, which would seem to indicate that there isn't a suction leak.
I've looked at numerous threads on failure to prime and haven't seen explanations other than suction side air leak or impellor obstruction. Can the pump just become weak over time, or do they just suddenly stop working altogether? I'm prepared to replace the pump with I can actually read the label on, but I'd obviously prefer to save that money (or spend it on something else)! Any ideas?
Water temperature is nearing 60 degrees, so I need to do something soon. Thanks to TFP, I've been crystal clear since I finally beat the green two years ago when opening the pool for the first time since we bought the house.
Edit: Not that this could be a factor, but the (current) priming trouble started after replacing my SWG. (I removed it for the winter and created a new section of PVC to replace where the SWG goes using unions.) I don't see any leaks on the pressure side at all, though. Also, a friend of mine told me using backwash mode on the filter seems to help fill the lines and remove air from the system, so I tried that, but it didn't help. Right now the pump is putting about 8 PSI on the filter. Normal is 16-20 PSI. Can problems on the pressure side cause failure to fully prime?