Mag12 - Grinding?

[Amador]

Hey all, I'm running a Mag12 return in my sump. I'm running it submersed and it makes a scratching or grinding type sound. It's made this noise ever since I bought it.

I don't think it's supposed to sound like this. It's not really a vibration-type noise, more of a harsh grating noise that comes and goes very quickly. The pump is immersed in about 8" of water at all times, but it has sucked air a few times in its life.

Could it be sand in there? Or air? Anyone have a way to clean it or quiet it down? Any ideas would be GREATLY appreciated as it is driving me crazy! Thanks!

 

[larryl]

I have found that the Mag Drive pumps run a lot quieter when they are pushing against some back pressure or if they are throttled back a little bit. I turned the ball valve I have on the output to restrict the flow a little bit and mine got a lot quieter. If that does not work, inspect the impeller and see if there are any bits of flashing or small ridges of plastic that look like they got left over from the molding process. I had one that ran noisy even with the output restricted, but it got quiet when I smoothed out a couple ridges on the impeller with a utility knife.


Larry

 

[Amador]

Hey Larry, thanks for the tips. I opened her up and looked at the impeller and it mostly seems pretty smooth. I did see a couple of ridges on the back of two of the impeller blades (back being the side that faces opposite the inlet) - could these be causing the noise?

I also have the pump's output connected to a "T", with one side going to the fuge (and a ball valve) and the other side going back up to the display. Unfortunately no matter what position I set the valve at, the noise continues.

I did try a couple of tests while I had everything disconnected, and the noise is not as loud when the pump is not resting on the bottom of the sump. I stuck a rubber mousepad I had underneath the pump and that seems to help a little bit. Still a little worried since I am just treating the symptoms and not the cause.

 

[UFreefer]

check to make sure the washers look good, if they get worn out at all they will make the sound your talking about

 

[Amador]

Which washers should I look at? I only bought the pump a few months ago, and it sounded like this the very first time I plugged it in. Could they be bad right from the factory?

 

[UFreefer]

the washers on the impellor, if the impellor is off balance at all, it seems that the washers are the first things to wear out, once they wear out then the impellor breaks

 

[larryl]

I also have the pump's output connected to a "T", with one side going to the fuge (and a ball valve) and the other side going back up to the display. Unfortunately no matter what position I set the valve at, the noise continues.

With the valve to the fuge closed, you still may have very little back pressure in the line going to the tank. I have valves in both branches and by turning them both down a bit I can make it quieter. Is there any way you can shut the valve to the fuge and then temporarily restrict the line to the tank to see if it makes a difference? E.g. pinch down if it's flex tubing, or stick a thumb over the outlet or something?

Another possible source of noise is cavitation at the input - the pump might be pulling against too much pressure and causing bubbles to form in the impeller. You said it's running submerged so that's less likely in your case, but do you have anything at all on the input side that could be restricting flow?

 

[dvanacker]

Mine made the same noice and I found out the rubber stubs that hold shaft had worn down and the shaft was spinning. I used teflon tape to make it snug again and the sound went away.