Troubleshooting Swimming Pool Pumps
Before you start to work on the motor, MAKE SURE THE POWER IS OFF. Always turn the power off at the electrical
service entrance breaker box or fuse, to prevent electrical shock.
Pump very noisy
There are several possible causes for a noisy pump. First, it is necessary to determine if the noise is actually
coming from the pump or the motor.
Pump leaking water
Pump leaks can occur in several places and should simply be repaired whenever they appear. If the leak is around
the mechanical seal of the pump (see above), the pump should be shut off and repaired ASAP.
When replacing the seal the bearings should be replaced also ( the leaking water damaged the front bearing)
Whenever a new motor is installed, an entire seal kit should be installed as well. This includes a pump seal, seal
plate o-ring or gasket, lid o-ring and diffuser o-ring or gasket. This will help to insure that you do not have to take the
pump apart a month later to replace a small failed seal, o-ring or gasket.
Motor noise is almost always a problem with the front bearings on the motor. Usually this happens when a leaky
pump seal sprays water onto the front of the motor. When the water gets into the bearings, it will ruin them in a very
short period of time. It is possible to put new bearings on a motor, but most people just replace the motor.
Some pumps tend to make a lot of noise. This could be several possible things:
Pump restriction. If a pump is running under excess restriction, such as a clogged intake, full trap basket or other
obstruction, it will be much louder than normal.
Cavitation. If a pump is starved for water it will tend to cavitate. This makes a lot of noise because the pump is
working against itself.
Over-Performance. If a pump is moving more water than intended (has much less restriction on the return than is
intended), then it will tend to make a lot of noise. If, for instance, you run a poolsweep pump without the poolsweep
unit attached, then it will make a lot of this type of noise.
Internal Blockage. Sometimes something will get pulled into a pump that will cause it to make a lot of grinding noise.
Also if the impeller on an Aqua-Flo pump is touching the face of the volute, it will make a grinding noise.
Pump hums and shuts off
Sometimes a pump motor will make a humming noise and then shut off with a "click". The problem is that the motor
is failing to start turning. With a stationary rotor, the motor quickly overheats and the temp sensor cuts it off. If the
power is left on, the motor will cool down and then go through the process over and over again.
There are a several possible causes for this:
If the start capacitor is bad, it will cause the motor to fail to begin turning. Many pool motors are replaced
unnecessarily each year because the owner or tech did not know to check for a bad capacitor. A new capacitor
costs $25-$35 while a new motor costs $200 or more. The only way to accurately check a capacitor is with a digital
multimeter that will give an exact reading of capacitance. In the absence of a multimeter, you can try a new
capacitor of the same mF rating and see if it works.
If there is sand or other debris stuck between the impeller and the pump body, it can make it difficult for the motor to
turn over. The best way to check this is to turn the power off and attempt to turn the shaft of the motor by hand. If it
will not turn, then disassemble the motor and check for obstruction.
If the line voltage, as measured at the motor terminals is not within 10% of the specified motor voltage, then it can
cause a pump motor to fail to start. Sometimes the problem is that the wiring to the motor is insufficient, causing a
sometimes pool motors get old and start overheating. At this point it is best to simply replace it.
Pump cycles on and off
Sometimes a motor will just cycle on and off at regular intervals. This occurs when the motor is running just a bit
too hot. When it gets hot enough, the thermal sensor will cut it off until it cools down, then it comes back on. There
are several possible causes for this:
The motor may be receiving improper voltage
If the voltage to the pump motor is 10% above or below the voltage stated on the motor specifications, then it may
Check the voltage at the terminals at the back of the motor. If it is too low, either the wiring leading to the motor is
insufficient or the power to the house is just low. Sometimes the power company fails to properly regulate the
power and high or low voltage can ruin a motor over a period of time. We have seen situations where the installer
wired up the pump with wire that was too small for the power requirements. As a result, voltage is lost due to the
resistance of the wire.
Check the wiring diagram on the motor. Most pool motors can be connected either 115 or 220 and sometimes
installers get it wrong. If a motor is hooked up improperly, it may run for a while, but the likelihood for long term
damage is pretty high.
Check the wiring connections to make sure they are all tight. Sometimes connections will loosen up over time and
will result in much less contact between wires.
The pump vents may be blocked
Pool motors are air-cooled and if the air flow is blocked, this may contribute to overheating. Be sure to keep leaves,
dirt and anthills from collecting around the back of the motor.
The pump may have internal blockage
The pump motor may be running hot because of internal blockage. Sometimes sand or fibers gets into the impeller
and can make the motor work extra hard to get the job done.
The pump may have an internal short in the windings
If there is an internal short in the windings, the motor may overheat. In this case, the motor will need to be replaced.
The windings have a clear insulation on them which can get burnt off and cause the motor to overheat. This is
generally the result of old age.
Troubleshooting Swimming Pool Pumps