WFE-6 Impeller? Motor?

[aspinfo]

I can't get my pump to prime. It will get close and bubbles come out of returns, but then in less than 5 minutes, loses everything. Isolated each skimmer & main drain and in all three cases, with only one source open, same effect. Removed diffuser and visually inspected front of impeller, no rocks or obstructions. Motor sounds fine and creates good suction on basket cover. If I fill basket up to full, it sucks that water out immediately. Resolved small air leak at a trap that I open to blow lines out and it now holds standing water above fitting, so no leak there.

Suspicious of something in motor. Last year, system suddenly ran dry one day near end of season and melted basket. Cleaned out impeller and all seemed good, but not sure if seals, bearings, etc., could have been affected. Replacement motor is $300, but looking for other ideas first.

 

[JasonLion]

The problem you describe doesn't have anything to do with the motor. Air is getting into the suction side plumbing, causing the pump to lose prime. See the article in Pool School on finding a suction side air leak.

 

[aspinfo]

Jason, you nailed it. Thank you so much. I found that I had two air leaks in PVC joints on the suction side. One is on the vertical joint coming out of the pump on the way to the filter, there's a drip and another one on the last joint before the pump. Both look like there was some goo applied around the joint 10 years ago, but over the cold winter or from moving them around while taking the pump apart 3 times and reinstalling 3 times, might have exposed/cracked. Applied some silicone beading all the way around them and its holding for now, full power achieved. What is the permanent adhesive for that? I have the primer & cement used to join pvc pipes together. Is it that or something else in place of the silicone?

Also, does the filter go through cycles every minute or so? Seems like pressure stays near 20 for a minute, then you hear a change and it jumps to 30 for a minute, then repeats. Is that normal for a Purex Triton 60 filter?

 

[JasonLion]

The only truly permanent fix is to replace all of the PVC involved. Occasionally you can fix a joint with PVC cement, but it usually doesn't work. Trying silicone can sometimes work for a while, but will fail again.

The filter pressure should not vary except over several days (or longer). That suggests you haven't gotten all of the air leak.