Strainer Assembly Crooked on Brand New Pump


Active member
Jun 8, 2009
Pittsburgh, PA
I was looking over my new Pentair Dynamo pump last night in preparation for the install today. I noticed something disturbing. Unlike my previous pump the part that holds the strainer (circled in blue below) screws onto the pump housing like two peices of NPT pipe going together. I've marked where it screws in with the red arrow. There's a rubber o-ring there to seal the junction.

On my previous pump the strainer part was affixed to the pump body with bolts.

What's troubling to me is that if I screw the strainer assembly on so that it ends up perfectly vertical the rubber o-ring inside is barely compressed and the joint doesn't feel snug enough. In my estimation the strainer body just isn't screwed on tight enough.

If I do screw the strainer body on tight enough (my opinion of tight enough) the strainer body ends up about 10 degrees off vertical.

I'm doing a rigid pvc install so I have to get this right from the start. Do I screw the strainer body on until it's perfectly vertical or do I screw it on until it feels snug enough?


Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
Houston, Texas
You can test it and see if it leaks at the joint before installing the pump. I have the same pump and there is a little wiggle at that point, but it does not leak. Also, unless they have changed the coating on the bolt down brackets for the pump, you will want to give them a couple of coats of clear finish top and bottom to prevent rust. If you can add a thin rubber gasket that would be even better. My brackets started to rust after the 1st year and by the time it was 4 years old the brackets have rusted away, but the pump still runs great! It is also a good idea to get some gasket lube and coat the o ring on the strainer basket lid well. Mine fits good and tight and before I learned about gasket lube it took a pry bar and all my strength to twist the lid off!

Bama Rambler

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2009
SouthWest Alabama
The way that connection is designed it's not supposed to be mechanically tight. The o-ring is the sealing surface and it only needs to be threaded inside the union far enough to sit on the mating surface.

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