Replaced capacitor, motor still makes humming noise. Won't run. Runs when shaft turned over by hand.

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C

crosley

Well-known member
Mar 27, 2014
46
Arizona
Have a Pentair single speed pump, 3/4hp. Flipped motor on, made a loud pop, strong smell. Capacitor blown, covered in liquid. Seemed like an easy replacement.
Replaced capacitor with identical brand and specs. Still just hums when turned on. Motor shaft spins freely. Will start and seems to run fine when shaft is flipped over by hand.

Motor has low hours, impeller seems to turn fine by hand.

Any ideas?
 
crosley said:
Have a Pentair single speed pump, 3/4hp. Flipped motor on, made a loud pop, strong smell. Capacitor blown, covered in liquid. Seemed like an easy replacement.
Replaced capacitor with identical brand and specs. Still just hums when turned on. Motor shaft spins freely. Will start and seems to run fine when shaft is flipped over by hand.

Motor has low hours, impeller seems to turn fine by hand.

Any ideas?
Click to expand...
Burned start windings. There are two sets of winding in a motor, the start and run. Start windings come out of the circuit once the motor gets up to speed. A switch of some sort does that job. New motor time.
 
Pentair #196237

Replacement pump

Century (A.O. Smith) .75 HP Full Rate Motor, Square Flange 56Y Frame, Single Speed - Model B847 - B2847V1 - INYOPools.com

Century 3/4 HP Square Flange 56Y Full Rate Motor - B2847V1
www.inyopools.com www.inyopools.com

I don't believe it has a switch as I don't see one when I removed the rear.

My plan is to just replace the motor, just wanted to make sure I wasn't junking it for a small part. When I flipped the breaker, the capacitor blew up. That's why I was surprised after replacing the capacitor, it didn't fix it.It has very low hours on it, used as a spillway pump.

Any advice on replacement motors? There's a local shop that sells rebuilt ones that has a good reputation. I'm fine paying more for quality, but it seems all of these motors have gone offshore, almost wonder if a local rebuilt one might work better.


Curious why it happened, motor is older but probably has around 100 hours on it.
 
crosley said:
Pentair #196237

Replacement pump

Century (A.O. Smith) .75 HP Full Rate Motor, Square Flange 56Y Frame, Single Speed - Model B847 - B2847V1 - INYOPools.com

Century 3/4 HP Square Flange 56Y Full Rate Motor - B2847V1
www.inyopools.com www.inyopools.com

I don't believe it has a switch as I don't see one when I removed the rear.

My plan is to just replace the motor, just wanted to make sure I wasn't junking it for a small part. When I flipped the breaker, the capacitor blew up. That's why I was surprised after replacing the capacitor, it didn't fix it.It has very low hours on it, used as a spillway pump.

Any advice on replacement motors? There's a local shop that sells rebuilt ones that has a good reputation. I'm fine paying more for quality, but it seems all of these motors have gone offshore, almost wonder if a local rebuilt one might work better.


Curious why it happened, motor is older but probably has around 100 hours on it.
Click to expand...
Haven't taken one of those motors apart in a few years. Don't remember, but it may have one of these switches in it:
capacitorwarehouse.com

Century D Shaped Start Switch

Electric motor start switch, Century start switch, Magnetek start switch
capacitorwarehouse.com
capacitorwarehouse.com

Century L shaped Electric Motor Start Switch

Electric motor start switch, Century start switch, Magnetek start switch
capacitorwarehouse.com
 
1poolman1 said:
Don't believe there is a mechanical switch under that end bell. Sounds like bad start windings.
Click to expand...

Any guidance on buying an up rated or full rated motor? Is one more long lasting than the other? I was going to go with 1hp. The current 3/4 hp motor I have is underpowered. I see things mentioned on the "full rated" like ball bearings?
 

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crosley said:
Any guidance on buying an up rated or full rated motor? Is one more long lasting than the other? I was going to go with 1hp. The current 3/4 hp motor I have is underpowered. I see things mentioned on the "full rated" like ball bearings?
Click to expand...
If you don't change the impeller, it doesn't matter what bigger size in horsepower motor you install, it will still be a 3/4hp (1.25THP) pump. That's the maximum amount of work that impeller will do. Larger horsepower motors will still only spin at 3450 rpm max but would use more energy just because there is more wire in them, though not a lot more. There is no benefit to up-sizing the motor without doing the same with the impeller.
All pool motors have ball bearings. Any motor you get should be "full-rated."
 
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