Hayward 1 1/2 Super Pump humming noise

[Madty]

Pumps working fine- has a cycling humming noise. Hummm hummmm quiiet, etc...
Just started yesterday- doesn't sound like bearings or anything metal rubbing. I took off the cover and impeller turns fine without any noise.

Btw, the pump is only about 9 mos old.

Any ideas?

[Poconos]

Just a guess but I wonder if you're hearing the beat note between the 60 Hz and the rotational speed which is around 3450 RPM, or 57.5 Hz. That's a 2.5 Hz difference and is a rotational slippage necessary for these types of motors to work. . Sounds like what you're describing is a slower beat though and I can't explain why it just started.
Sorry.
Al

[Madty]

Al-
I have no idea what you just said lol It's sorta loud and more than just a electrical humm noise- I know it's hard to explain on a forum like this- it just doesn't sound like a squeal or a grinding sound.
Thanks

[Poconos]

Sorry, sometimes I get carried away so let me try again. Assume the motor isn't turning but has power. You will hear a hum because of the 60 cycle per second current in the windings. Hertz and cycles per second are the same and the terms can be used interchangeably. This hum is due to small vibrations in the winding due to the magnetic field being generated by the 60 cycle power. The magnetic field is reversing 60 times a second. Sometimes this hum may be loud and sometimes you may not be able to hear it at all. Now, if this was a synchronous motor the rotational speed would be that of the alternating current frequency, or 3600 RPM. (60 cycles per second, or Hertz, AC current X 60 seconds in a minute.) These motors are not synchronous however so the rotational speed is a little less than 3600. If you look on the plate they will usually state 3450 RPM. Divide by 60 seconds per minute you have 57.5 Hertz. So now you have two sources of noise, the 60 Hz hum, and the 57.5 Hz mechanical noise. What you can hear in some motors is an increasing and decreasing hum level at the difference frequency or 2.5 Hz. Sometimes I suppose the electrical hum can get loud if a bolt loosens inside on something related to the winding assembly. If what you're hearing gets louder and softer at the 2.5 cycle rate then what I described could be your situation. I have a feeling not. Other than this I still have no ideas.
Al

[Madty]

Thanks Al- I understand...uh, a little. I went out a little while ago and it was quiet. Then I heard a little noise- I guess just wait and see. I know everythings turning because the water is pumping fine.

Thanks again

[thepoolman1]

Sounds like a rear bearing noise to me, especially if the motor is a Magnatek/Century. The rear bearing cup in these motors is slightly large, allowing some lateral (side-to-side, up-and-down) movement. Get something stuck in the impeller and it gets out of balance. This can increase the tendency for the motor shaft to move and you will hear it as a "rum, rum, rum, etc" noise. Eventually the bearing cup gets larger and the noise worse.

Got this information from a motor shop many, many years ago. If it is a Magnatek/Century motor, the quick fix is to remove the end bell, wrap a couple of turns of teflon tape around the bearing, re-assemble the motor. Sound should be gone. Has worked every time for me. This can be done with A.O.Smith motors also, but they are more difficult to take apart due to the centrifugal switch on the end of the motor shaft. On re-assembly the switch contacts have to be adjusted properly also and the end bell seated properly and the through-bolts on both brands tightened evenly so the bearing is aligned properly.

[Poconos]

That would certainly explain why the beat note is now loud enough to hear. Great information for the archives in the brain.
Thanks.
Al