Pump Noisy or Low Output.. Read on.

[Pegasus]

Pump Noisy or Low Output..

Air pumps today are pretty reliable, and also fairly cheap, but there comes a time when the output begins to fail and we get a very low output, along with an annoying rattle or buzz.

Below are a few tips to let you service the pump and get a little more life from it.

First “Disconnect the power†before attempting any repairs.

We will consider the “Double Diaphragm†type, but the Single Diaphragm models work just the same.

Remove the rubber back of the pump to expose the inside.

Here you will see the pump body unit, along with the rubber diaphragms and two arms with magnets attached.

There is also a coil in there that is switching on an off at 50 cycles a second, (when plugged in).. and this causes the magnets on the pump arms to oscillate across the face of the coil, and as they do so, the diaphragms are pushed in and out at high speed.

Don’t fiddle with the coil or any electronic controls that might be there, as they are non-serviceable parts and will need replacing if they fail.

Reduced output from air pumps is caused by two main reasons.

The first is a split or perished diaphragm, and the second is sticking or worn valves. Pumps that suddenly become noisy usually indicate a worn or torn diaphragm, or that the diaphragm has worked loose from its seating.

On most pumps the pump body is designed to be removed as a complete unit, along with the diaphragms and magnetic arms.

Look carefully at the assembly before removing anything, and if needed make a little sketch or how the assembly looks. There should be no need to apply any force in the removal or assembly, so take care and just take your time.

Now remove the pump body as a unit.

It is unlikely that the left and right diaphragm arms are different, but just in case, take note.

Now carefully peel back the diaphragms from the pump body to expose the valve assembly. Lift the arms clear of the pump body and put to one side.

The valve assemblies vary with different types of pumps, but they all basically work in the same way, and that is that a small rubber membrane sits over a hole in the pump body and is “lifted and pushed†(opens and closes).. at each stroke of the magnetic arms oscillate across the face of the coil.

As the diaphragm forces air into the pump, one valve opens to allow the air to get “inâ€.. while the other valve “closes†to stop the stored air getting out.

With the diaphragms and magnetic arms removed, check the diaphragms very carefully for any signs of cracking, rips, or perished areas that will lead to leaks.

If these are damaged, then usually the stockist where you bought the pump will have replacements.

Now look at the tiny valves.

You will only be able to see only “one†of the valves fully, as the other is mounted between the two halves of the pump body.

Gently ease the valve up and look at the seating for signs of dirt or other rubbish.

Clean any staining or dirt off with warm water with a bit of washing up liquid in it, but ensure it is dry when finished.

This is Important:

Now put your finger on the top of the valve and push down firmly.

The valve has a thin rubber stem… like the one you can see protruding out of the other valve hole.. and this pushing action ensures that the valve is fully seated correctly.

Without splitting the two halves of the pump, there is not much you can do about the other valve, but this one does not often cause any problems apart from losing its seating.. so gently grip the thin stem that is protruding from the valve hole and “GENTLY†pull it out

This will again ensure that this valve is seated correctly on its seat.

Now do a “blow and suck†test on the pump by blowing and sucking on each side of the pump. Your mouth is acting as the diaphragm here, so you will need to get a good tight seal.

You should be able to blow or suck one way .. but not the other.

If you get this result, then the valves are fine.

If you “do†get some leakage, then go over the above again.

If they “still†won’t seal, then you may have to split the two halves of the pump body to get to the second valve.

This is pretty straightforward, but just be careful not to rip the thin rubber gasket, and make sure it is fully airtight once assembled. Check this second valve as per the above making sure it is well pushed onto its seat.

Test the diaphragms the same way by sucking on them to cause a vacuum.. as any leakage will soon be apparent.

Ensure they are sitting correctly (fully) on the pump body when you assemble them.

There is a small filter in the back of the pump.

Remove this and make sure it is clean and clear.

Re-assemble the pump and test.

HTH.