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I purchased 3 identical submersible water pumps for my irrigation mister heads.

Im running them in clear tap water at room temperature(blockages are not a concern)

After running one for 30 hours, the vibrations are became abrupt and noise has became noticeably louder.

I swapped it over with the second pump, which at first seemed to run smoothly, but after 20 hours now makes loads of noise.

The third pump has followed the other two 40 hours later...

When turning all three pumps off and on again, they sometimes run smoothly, sometimes run abruptly, however, even when running smoothly, it only takes 1 or 2 minutes before they run abruptly and vibrate / make alot of noise

Suction fixings remain secured. Power source is fine.

Pump specs

  • Cost £20
  • 1500LPH
  • Head 2.1m
  • Centrifugal mag drive
  • 25watts / AC 240v

Picture of actual pump enter image description here

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  • $\begingroup$ may be cavitation ... is the intake obstructed somehow? $\endgroup$
    – jsotola
    Commented Aug 28, 2023 at 15:19
  • $\begingroup$ Definitely not intake obstruction, but could be opposite - my outtake is too less as my misters only allow for 1lpm $\endgroup$
    – David jones
    Commented Aug 28, 2023 at 17:02
  • $\begingroup$ what happens if you obstruct intake and outlet? $\endgroup$
    – jsotola
    Commented Aug 28, 2023 at 20:54
  • $\begingroup$ divert water back into the source ... send only some of it to the irrigation heads $\endgroup$
    – jsotola
    Commented Aug 28, 2023 at 21:21

3 Answers 3

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The one thing the comes to mind without hearing the noise is bearings. Try adding some lubricant to the shaft if its running on a plastic clearance.

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  • $\begingroup$ Could be a possibility. I will try and report back. The noise only goes away after turning off the pump and restarting it, however I only get smooth operation for about 1 minute and the noise returns $\endgroup$
    – David jones
    Commented Aug 28, 2023 at 14:48
  • $\begingroup$ Is your power source okay? If is abit intermittent then load/ pressure changes could make such noise. A sound clip would also be a nice to have . I also would have thought the tank water would have damped out any noise because it's submersed. $\endgroup$
    – Sami Safarini
    Commented Aug 28, 2023 at 15:02
  • $\begingroup$ Added a new picture to opening post, nd some more text mid-body, tried adding washers to the shaft to prevent any Impeller movement, but it hasn't done anything, noise still comes after 1 minute of pump being switched on $\endgroup$
    – David jones
    Commented Aug 28, 2023 at 15:03
  • $\begingroup$ Sami, it's definitely not a power issue, as for the water tank dampening noise, it's some type of fault because the pump starts quiet with a fine hum, then gets progressively violent $\endgroup$
    – David jones
    Commented Aug 28, 2023 at 15:04
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    $\begingroup$ I will make a video to show the noise difference $\endgroup$
    – David jones
    Commented Aug 28, 2023 at 15:04
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I would check the inlet to be sure there is no restriction and vibration. They are essentially the same as aquarium pumps, many styles by various manufacturers. They are lubricated and cooled by the water. I may have had one hundred over the years. The alumina shaft ( white) which yours has are excellent. I have had the stainless steel shafts wear out after years of service.

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  • $\begingroup$ The thing I don't get is everything is remaining the same, in terms of the pumps position, water temps, etc. When you say check the inlet, what for? $\endgroup$
    – David jones
    Commented Aug 28, 2023 at 14:54
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Air is accumulating in the pump chamber with use. When that happens, the pump starts making noise and the water output decreases.

This happens when the suction created by the pump is great enough to draw dissolved air out of solution from the water. When slung about centrifugally by the impeller, that air accumulates near the center of the impeller and becomes difficult to scavenge out.

This means the resistance to flow that the pump "sees" in its inlet pipe is too great for the pump to manage.

You can easily test this by placing the pump with no pipes attached in a deep bucket full of water and turning the pump on. in this case the pump should run indefinitely with no air buildup, and will not start making noise.

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  • $\begingroup$ I think your answer is in the right direction, but not quite right still... i just put a hosepipe on the outlet of the pump, when the water is flowing freely there's no noise, however, if I squeeze the hosepipe to reduce flow the pump begins making violent noises... therefore it seems to be that my misters may not be allowing enough flow rate. $\endgroup$
    – David jones
    Commented Aug 28, 2023 at 16:55
  • $\begingroup$ If flow rate is the issue at hand here, I wonder why the pumps are fine for the initial 30 hours, but once the violent noise starts, they can only operate normally for 1 minute after powering off and on, what inside the motor / internals is changing? $\endgroup$
    – David jones
    Commented Aug 28, 2023 at 17:00
  • $\begingroup$ your first comment is the key! you need diaphragm pumps instead of impeller pumps, they work much better for higher pressure/lower flow conditions. $\endgroup$
    – niels nielsen
    Commented Aug 28, 2023 at 17:27
  • $\begingroup$ Il check them.out but they sound expensive $\endgroup$
    – David jones
    Commented Aug 28, 2023 at 17:28
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    $\begingroup$ It's called cavitation $\endgroup$
    – niels nielsen
    Commented Aug 29, 2023 at 5:10

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