I have a pump with a leak at the outlet where it connects to a 2" PVC male adapter.


In order to fix the leak I did some reconfiguration - raised the pump, added in two unions. and remade the threaded connection.

I did the threaded connections using RectorSeal T Plus 2 pipe thread sealant. No leak after that...or do I thought.
Today I fired up the pump and I after it primed, I observed no leak. An hour later I came back and I saw a slow leak at the outlet again. Same exact spot.
Since I have added two unions, I took them apart and I noticed the male adapter is not TIGHT-TIGHT into the housing. I know I hand tight that connection, then used a pipe wrench to go one more revolution. Now it is a bit loose. Hmmm, I suppose the vibration and movement of the pump worked the connection loose?
In the reconfigured plumbing, I have three threaded joints, one between the suction side manifold and the union (#1), one at the inlet of the pump (#2), and one at the outlet of the pump (#3). They were all made the same way, yet only the outlet side is leaking. Of course the other two are being subjected to negative pressure, while the outlet connection is subjected to positive pressure.

After I took apart the unions, I remove the male adapter, cleaned both the female connection at the pump and the male adapter real well, and used MEGAMAX tape instead.


Then I remake the connection, started the pump, and it leaked again.
Any idea what else to try? Use pipe sealant AND tape?


In order to fix the leak I did some reconfiguration - raised the pump, added in two unions. and remade the threaded connection.

I did the threaded connections using RectorSeal T Plus 2 pipe thread sealant. No leak after that...or do I thought.
Today I fired up the pump and I after it primed, I observed no leak. An hour later I came back and I saw a slow leak at the outlet again. Same exact spot.
Since I have added two unions, I took them apart and I noticed the male adapter is not TIGHT-TIGHT into the housing. I know I hand tight that connection, then used a pipe wrench to go one more revolution. Now it is a bit loose. Hmmm, I suppose the vibration and movement of the pump worked the connection loose?
In the reconfigured plumbing, I have three threaded joints, one between the suction side manifold and the union (#1), one at the inlet of the pump (#2), and one at the outlet of the pump (#3). They were all made the same way, yet only the outlet side is leaking. Of course the other two are being subjected to negative pressure, while the outlet connection is subjected to positive pressure.

After I took apart the unions, I remove the male adapter, cleaned both the female connection at the pump and the male adapter real well, and used MEGAMAX tape instead.


Then I remake the connection, started the pump, and it leaked again.
Any idea what else to try? Use pipe sealant AND tape?