How loud is a bad start capacitor?

[shellsingleton]

I have a 1 hp WhisperFlo pump on my water features( 2 sprays, 3x18" falls), powered by a 1 hp AO Smith motor. It is a switchless.
When I turn it on, there is an extremely loud buzz, then it trips the breaker within a couple seconds. It was so loud, I figured the motor was locked up, but after some more research, I wonder if it could be the start capacitor?
The impeller spins fairly freely by by hand (although it's easier in one direction than the other), so I assume the motor's bearings aren't frozen.
Also, there is no "MFD" number that I can see on the start capacitor. So how can I know which one to order? It is made by Magnetek, and I think it is model number 0102(kinda rusty in spots). there are 3 groups of numbers following that: 60P68-2448, 175663 50-60 Hz, S 1000-AFC.
Thanks, Shell

 

[shellsingleton]

Re: How loud is a bad RUN capacitor?

Update:
That's a run capacitor, not a start. And the funny "u" symbol denotes the MFD, which in this case is 50. And is a 370V unit. Local electric supply was very knowledgable and willing to help.
I have a new capacitor ordered, should be here Monday.

A couple other questions remain:
Is is normal for an impellor to spin more easily one direction than the other?
Are run capacitor failures capable of producing a buzz loud enough to hear from 50-60' away, or would you suspect something else?

 

[Bama Rambler]

No wonder my hours (ok really minutes) of searching didn't turn up anything! Glad you got it figured out.

The seal gets a set in it and could allow it to spin more easily in one direction than the other.
It's possible to hear a buzzing form a long way away when the motor isn't starting because the cap is bad.

 

[JasonLion]

Depending on how the capacitor failed, it is possible for it to be very loud, though normally it isn't as loud as you describe.

 

[shellsingleton]

Great! Thanks guys. I'll replace this cap when it comes in and go from there.
If it runs again, but is loud, I'll look into the bearings. Will change the seals at the same time.
Was good to hear that the seal may cause more drag in one direction.

 

[shellsingleton]

Run capacitor is not the problem. Made no difference. Will remove the pump tomorrow and investigate further. If anyone has an idea of what to look for, I'm all ears. It "sounds" like it's shorting to me, but there's no smoke or smell.

 

[Durk]

My guess: centrifugal switch is stuck in run mode, and lack of start cap/winding action means motor can't get going. This can definitely cause a serious buzz. Non-turning motor causes much higher current draw through run coil and breaker trips.

 

[shellsingleton]

How does this motor come apart? From the front?
I have removed the 4 long shank bolts that went all the way through the motor. I have removed the 3 short external screws that were holding some type of internal dust shield(?) near the end of the motor. I have tapped it with a plastic head mallet. No movement. I was expecting to be able to take a rear cover off, but now I'm suspecting it may have to be disassembled from the pump end.
I have removed it from the pump, have removed the reverse threaded impeller screw. The impeller is stuck on the shaft and looks to be pretty delicate at this point. It may be 12 years old, not sure when it was installed. Is there a trick to prying them off, or is there a pin or keyway I didn't see? Trying not to pry if I don't have to.
Thanks, Shell

 

[Bama Rambler]

If you've got all the screws out, take a screwdriver and place it on the seam where the bell end (rear cover) meets the stator housing and strike it pretty hard. It should move. You'll have to strike it in several places most likely. Mark the bell end and the housing before disassembling.

 

[mac05]

Hi, Shell.

If you have an older WhisperFlo, they may have blanked out the model number of the motor. According to AO Smith's site, they are the same as Magnetek Motor Division. You can find much information at the AO Smith site (aosmithmotors.com). For example, a little research at the site showed that the WhisperFlo WF-6 pump uses the AO Smith B842 1.5 HP motor. Also, the B842 has been replaced with the B2842. Your pump is probably similar.

No matter which motor you have, the AO Smith website tells us which replacement parts to buy. If your local pool supply does not carry bearings and capacitors, your local W.W. Grainger branch will have all that you need. (Grainger.com) Grainger prices can be a little high, but the customer service is beyond compare.

To remove the impeller, you may have to hold the shaft steady while you twist the impeller off. If your motor has a metal cap at the end opposite the impeller, you can remove the cap to reveal the shaft with flat spots that accept an open-end wrench. Hold the shaft steady with the wrench while you turn the impeller. Your motor may be a little different, so here is a link to AO Smith's detailed manual. Good luck!

http://www.aosmithmotors.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=588

If the URL changes, you can search AO Smith's website for the "#3400 Pump motors" manual.