Cavitation or bad bearings?

Ellediem

Member
Apr 18, 2020
12
Georgia
Hope someone can help, I'm so frustrated. My 1hp pentair Super flo just died. My brother gave me a 1.5hp pentair Super flo he is no longer using. I am using it now and it makes the most dreadful noise. It chugs like a train and grinds. It is so loud I can hear it in my house. I don't know if the sound is bad bearings or cavitation from the pump being too powerful. Any ideas?
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
19,496
Bedford, TX
E,

What does it look like when running if you look down through the pump lid? What is your filter pressure when running? Is water flowing back into your pool?

Thanks,

Jim R.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Welcome! :wave: Bad bearings often have a squealing sound. Cavitation sounds like you have gravel in the pump basket. Can you can take a short video and upload it? Let's get some eyes & ears on that situation to see for sure.

Also, make sure you have good, unrestricted water flow to the pump. Pool water level good, all valves fully open, no possible blockage. An obstruction can result in similar symptoms of poor water flow. Use a pressure bladder or push water backwards from pump to pool with a garden hose and rag wrapped around it for a seal.
 

Ellediem

Member
Apr 18, 2020
12
Georgia
Hi, thanks for the replies. Jimrahbe, when I look through the pump lid the the water looks fine, full and no bubbles. The pressure on my filter reads about 21 which seems to be normal for my filter and water flow also seems strong in pool returns.
Texas Splash, I will try to get a video up. I don't think I have a blockage, because I just took my old pump off last week and everything seemed fine but, I will give your suggestion a try. Thanks for your help guys.
 

Randrx2

Bronze Supporter
Dec 13, 2018
374
Orlando, FL
Sounds like the impeller is hitting the casing. Turn off the power to the pump and try to reach in and spin by hand and see if it is rubbing.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
34,440
Sebring, Florida
You might have something caught in the volute or wrapped around the impeller but that is not cavitation
 

Ellediem

Member
Apr 18, 2020
12
Georgia
Thanks for the info. I'm kind of new at this. I just put this replacement pump in. My brother gave me his old 1.5 pentair Super flo to replace my 1 hp Super flo. I didn't know what the sound was and found this video on youtube. It sounded similar which concerned me that the pump might be oversized.
 

Randrx2

Bronze Supporter
Dec 13, 2018
374
Orlando, FL
Thanks for the info. I'm kind of new at this. I just put this replacement pump in. My brother gave me his old 1.5 pentair Super flo to replace my 1 hp Super flo. I didn't know what the sound was and found this video on youtube. It sounded similar which concerned me that the pump might be oversized.
Yes, that is cavitation. It sounds similar. But, the difference is that your strainer basket is full of water and the second video shows the strainer basket not full.

duraleigh had a good idea that it might be something stuck or wrapped up in there. Maybe a frog, snake, or pool toy?
 

Ellediem

Member
Apr 18, 2020
12
Georgia
The second video is not my pump, it's just a video on youtube. I checked for blockage and it seems clear.
The reason for my concern about cavitation is that we thought our pump was 1.5 hp. It broke a few days ago and we ordered another super flo 1.5. My brother gave us an old pentair superflo 1.5 to use while we waited for the new one. We took our pump off and noticed the motor said 1 hp but the plastic case was marked 1.5 hp. We put the temporary Super flo 1.5 on and it is making the worst racket. We were concerned it might be too much hp for our setup.
 

Randrx2

Bronze Supporter
Dec 13, 2018
374
Orlando, FL
Check to make sure all your discharge valves are open and all of your inlet valves are open. Also, what size is your piping?

The flow rate increase from 1 hp to 1.5 hp shouldn’t be that much. I am guessing about a 15 GPM increase. What is the make and model of your old pump?

Were you able to spin the impeller by hand? TURN OFF POWER TO PUMP. You may be able to determine if it is hitting that way.

Last resort is to disassemble the pump and look for obstruction.
 

Ellediem

Member
Apr 18, 2020
12
Georgia
My piping is 1.5" and my old pump was a pentair superflo . It's confusing because the plastic case was marked 1.5hp but the motor was marked 1hp. We did not realize that until we had already purchased a new pentair superflo 1.5 hp. My brother looked at the impeller and it seems ok.
 

Randrx2

Bronze Supporter
Dec 13, 2018
374
Orlando, FL
One more test you can do. Please note that this can damage pump if you do not do this properly. Because you are running a dry pump and not cooling the pump.

Can you valve off the pump inlet and outlet? If so, turn off pump, close the valves at the inlet and outlet, turn off power to pump, disconnect pump so that is isolated. Quickly turn power on to pump then off (basically, bumping the pump). Does it still make the sound? If so, it is a mechanical issue and not a hydraulic issue.
 

Ellediem

Member
Apr 18, 2020
12
Georgia
That's a great idea. I will try it when I get home. And yes, I learned the hard way about running a dry pump. That's how our last one died. Thanks again for all your help.