Need help with apparent shaft seal leak


New member
May 7, 2018
Phoenix, AZ
I have a Pentair Whisperflo pump. There is water leaking from behind the seal plate of the pump, under the motor. Exactly like you would expect from a bad shaft seal.

I replaced the shaft seal. Still leaking.

I replaced it again, thinking I might have accidentally touched it or got some dirt on it. Still leaking.

I called a pool repair guy. He also replaced the shaft seal. Still leaking. He then suggested rebuilding the MOTOR, which didn't make sense to me - if the problem is that water shouldn't be getting to the motor in the first place. How could rebuilding the motor fix that?

By this point, the leak had increased from an occasional drop to more of a steady flow.

I replaced the seal plate, thinking maybe there was a small crack. Still leaking.

I replaced the impeller, again thinking maybe there was a crack. Still leaking.

As far as I can tell, I've now replaced every part involved in the wet/dry separation.

I'm quite certain the water is not coming from somewhere else and running down under the motor. I can post a picture of the leak if that would be helpful.

What else can I do? Is it possible the repair guy was onto something with rebuilding the motor?

For now I'm just letting it run and leak. I know it will eventually ruin the motor, but at this point I've probably spent more on failed repair attempts than a new motor would have cost anyway.
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LifeTime Supporter
TFP Guide
May 22, 2013
Hudson, WI
:wave: Welcome to TFP tgibson11

+1 on the chance the motors shaft is not centered and might be wobbling or just spinning slightly off center due to a worn or bad front or rear bearing. In either case that motors shaft will them eat the pumps seal. Not saying that's the problem but it sure sounds likely.


TFP Expert
Mar 2, 2011
Is the impeller screw in and secure?

Can you definitely tell that it's coming from the seal?

Is it maybe coming from the gasket?

Do you have a picture?


New member
May 7, 2018
Phoenix, AZ
@Vickery, @Kiss4aFrog - Thanks for the suggestions. That seems quite likely after everything I've tried so far.

@JamesW - The impeller screw is secure. I'm 99% sure it's coming from the seal, or at least somewhere in that vicinity. I have also replaced the gasket just to make sure (and it needed to be replaced anyway).


New member
May 7, 2018
Phoenix, AZ
I replaced the motor, and that seems to have fixed the leak.

I suspect that during my first attempt to replace the shaft seal, I damaged some part of the motor while struggling to remove the impeller. After that, the shaft was slightly off center, such that the two sides of the seal were not aligning properly.


Sep 30, 2007
Rochester, NY
Wow I have EXACTLY the same problem that I'm currently struggling with just like tgibson11. Except my pump is a Sta-Rite Dyna-Glas with a 2 speed motor that I put on 4 years ago.
I opened this season to a leaking shaft seal. A little surprising since I replaced it 4 year ago when I installed the new 2 speed motor on the pump (I replaced all the seals at that time as well).

So this season I start the process just like tgibson11:

*New shaft seal - still leaking
*Shaft seal 2 - still leaking
*Changed the impeller only, keeping shaft seal 2 - still leaking
*I just ordered a back seal plate ($80) and was thinking about changing that unless you think it's a waste of time/money.

Now in retrospective, I wonder if something else is wrong?--- the original shaft seal that I changed at the beginning of the season was cracked and fell apart when I took it off, which I thought was a kind of an odd failure mode. But now I'm wondering about the shaft runout as someone else mentioned. However visually I checked the shaft and the bearings feel tight and it appears to spin on axis, but I have no way of measuring. There are no signs of shaft wear either. The motor runs very quiet and smoothly without vibration so I never considered that as a possible issue till I read this thread.

Looking for more ideas as I'm getting really tired of taking it apart :)