Prime won't hold.

[Dr. D.]

Hi,

I replaced the motor on my Hayward Maxflo pump with a Century 1-hp. The Century works fine, but now the pump won't hold it's prime.

As soon as the pump is switched off, it starts to gurgle as the water drains, but the level in the strainer basket doesn't go down until the draining has been going on for over ten minutes. That tells me the problem is not the Strainer Cover O-Ring.

I replaced the Housing O-Ring and followed tightening rules. It seemed to go well.

I did not replace the Diffuser O-Ring. Old one looked pretty good and none at the store.
I did not replace the Shaft Seal Assembly. They sent the wrong one and I didn't want to wait.
I did not replace the Diffuser or the Impeller. Looked OK.

Just to complicate things, I also back-washed the filter, took it apart and cleaned it, then re-torqued it to almost 150 pounds.

So, where do I start?

Did I mention it's Spring in Florida?
David

 

[duraleigh]

The motor on your pump is not the cause of your inability to prime. You have air that is leaking into the system.

If the air is leaking into the system on the pressure side, you should see a visible water leak. Since you don't, I would question the work you did on the filter. It is possible for the filter not to leak water under pressure but allow air in when the pump is off. As Richard 320 says, "The first thing to check is the last thing you fixed".

 

[pooldv]

Sounds like the filter is letting air in. Probably either the relief valve, pressure gauge or a piece of debris in the main seal between halves. I've had it happen both places. You might be able to hear the leak if you run the pump to get it all filled up then turn off the pump and listen around the filter for the air sucking in.

 

[ewkearns]

Just to complicate things, I also back-washed the filter, took it apart and cleaned it, then re-torqued it to almost 150 pounds.

Just to be sure..... when you retorqued, did you torque to 150 inch-pounds or 150 foot-pounds? If the latter, you may have damaged the filter housing......

 

[Dr. D.]

OK, yes I torqued the filter body to 140 foot pounds. And it is not nearly the first time. Investigating the filter and multivalve.

Thanks

 

[ewkearns]

OK, yes I torqued the filter body to 140 foot pounds. And it is not nearly the first time.....

It is your filter to do with, as you wish, but the manual calls for 150 inch-pounds, or 12.5 foot-pounds.... Jus' Sayin'

https://www.hayward-pool.com/pdf/manuals/ProGrid-DExx20.pdf

 

[Dr. D.]

So, filter and multiport valve seem OK despite my gross over-tightening. I'm sure that will give me trouble down the line. "If you're gonna be dumb, you gotta be tough."

BUT: "I replaced the Housing O-Ring and followed tightening rules. It seemed to go well.

I did not replace the Diffuser O-Ring. Old one looked pretty good and none at the store.
I did not replace the Shaft Seal Assembly. They sent the wrong one and I didn't want to wait.
I did not replace the Diffuser or the Impeller. Looked OK."

The gap under the motor's square flange between the square flange and the housing is leaking steadily. I believe this is THE leak and that it is coming from the Shaft Seal Assembly and that would explain the way it's draining down, while leaving the strainer basket full till last. Could it also be the Diffuser O-Ring? I haven't really figured out what it does.