external pump, Blueline 40X, just got real noisey

[mogulski]

for some reason.
so i disconnect the unions that i plumped it in with. take the housing apart as well as inspect the impeller. looks good and clean, no obstructions. put it back together and it's still noisey as heck. oh yea it still runs cool as a cucumber.
any ideas?

 

[PyroJon]

I am having a similar problem with the same pump. I switched it's input plumbing from 1" to 1.5" and suddenly it's loud with cavitation noise. Sofar the only fix I have found is to close down the gate valve on it's imput to restrict it back down to somwhere near 1".

 

[JohnK]

Sounds like it was reasonablly quiet, then became loud, right?

could there be a vibration issue? Is the pump touching anything? Has anything changed in how it's installed/plumbing? Is it sitting on any kind of vibration damper (mouse pad, rubber pad)? Is the pump fully primed (could there be some air trapped in the pump/plumbing)?

Also, is the fan section dirty or obstructed?

 

[Scuba_Dave]

My 30 just became loud about a month ago
Took it apart, cleaned it, same thing
Same plumbing for a long time

 

[JohnK]

How old are peoples pumps that are developing this noise? Is is a bearing noise, or something else? Mine's a couple of years old and still running fine.

 

[PeterCip]

I have a dolphin 1200 that did the same exact thing.. sounds like cavitation to me, but I can't get it to stop. 2 years hooked up silent, then one day, really really noisy. I don't get it.

 

[Andy O]

What is cavitation? I have a blue line that i hooked up in February with 1" pvc and right off the bat if I had the gate valve all the way open it made a noise but when i dialed it back just a hair the noise stopped.

 

[PyroJon]

I don't believe that my noise is a bearing noise. There are no bearings in the impeller housing and that is where the noise seems to be coming from. Also, I can adjust how much noise the pump makes by simply restricting or opening the input plumbing. I would think that restricting the input would put more stress on the pump, making it louder, but it only makes it quieter.


What is cavitation?
When you move an object through water at high velocity it creates bubbles, this is cavitation. In your pump if you create bubbles you will hear the resulting noise. It's the same kind of noise you hear when you get air bubbles into a powerhead or most any kind of pump.

 

[JohnK]

In general restricting input on pumps is a bad thing, but I bet that if the impeller is worn or obstruced with Ca deposits or other gunk, a bit of input restriction might alter the forces on the impeller causing the worn/obstricted part to bind/rub/cause friction less?

I mentioned bearing noise, yes it would come from the motor housing not the impeller. All I can say is when you hear bearing noise, you know it's bearing noise, hight pitched metal on metal noise, gradually developing and getting worse over time.

I had an Iwaki WMD 40 RLT develop bearing niose after at least 4 yrs of non stop service (I think more like 6 or 7 yrs, but I forget for sure, need to check my notes). Gradually developed over a year or so, became unbearable. I even spoke to someone from IWAKI usa (located somewhere very local, Hopkington or somewhere not far from there, but not a retailer) and described the age, application, and noise. He said "bearing noise, age", replace the pump.