The pool pump has the most important job on the pool equipment pad, because when the pump is not working, nothing else works either.

How do I know what pump is right for my pool?
Contrary to selecting a pool filter, a bigger pump is not always a good thing. Unless you have been advised by a pool professional, or are otherwise certain that your existing pump was undersized, it would be wise to keep the same horsepower as you have now.

Different pumps produce different flow rates, even if they are the same horsepower. A 1hp Hayward pool pump will not produce the same flow rate as a 1hp Pentair pool pump. More important than matching pump horsepower, is matching pump flow rates. For instance, a 1hp Hayward Superpump is capable of 75 gpm, but a 1hp Pentair Whisperflo is capable of 115 gpm. This does not make the Pentair pump a ‘better’ pool pump, on the contrary, flow rates that are too high can damage your filter and piping, and result in ineffective filtration.

If the existing pump has done you well, it is easiest to replace a failed pool pump with the exact same make/model/size of pump. The height and length is also the same, which makes the plumbing job much easier. A different pump will usually require some adjustment to fit the pipes to the height of the front inlet and the length to the back discharge port. Dimensions of most pumps can be found on our pump pages, and some do match up, for instance Pentair SuperFlo matches up to Hayward Superpump, or the Hayward Superpump VS pumps, and Whisperflo pumps can be swapped out with Pentair Intelliflo VS pumps.

How do I know what Horsepower my pump motor is?
The horsepower should be listed on the nameplate (left) of the pump motor (in very tiny letters - hp). If the motor nameplate is burnt or worn off, a printed part number from the impeller can tell us which hp pump motor you have. This is because different horsepower pool pumps use different impellers. A motor manufacturer motor model number listed on the label can also be cross referenced with a quick online search.

Selecting a New Pool Pump
When buying a swimming pool pump, look for and buy a pool pump made by a major manufacturers; that is, Hayward, Jacuzzi, Pentair (American, Pac-Fab, Purex, Sta-Rite) and Waterway - well known market leaders. Other pumps of less recognizable brands are likely imported knock-offs of dubious quality, with non-existent replacement pump parts availability.

Remember that all pool pumps are different in hydraulics, shape, basket, lid, and colors. However, these may or may not matter a whole lot. Read on for more substantial ways to discern between filter pumps.
You will find that there are low head pumps for aboveground pools and medium and high head pumps for inground pools. The term "head" refers to the flow rate, in a backwards kind of way.
  • Above ground filter systems usually use a Low Head pump like a Dynamo, Hi-Flo or Power-Flo. Not self-priming, these are installed below water level.
  • Inground pools from 15,000-25,000 gals can use a Medium Head pump like a SuperPump, a Superflo or Magnum Force.
  • Pools over 25,000 gals could possibly use the High Head pumps like, Super II, Challenger, or the Whisper-Flo, with large enough plumbing and filter size.
The motors used on pool pumps are all nearly the same, most made by AO Smith, Century or Emerson. There have been many innovations in pump technology in the recent years, with the most notable being Variable Speed pumps, which use a completely different motor type.
For Variable Speed pumps to work well, you want to be able to use all speeds, and if you oversize a VS pump to your pool plumbing and filter size, it can cause problems. Fortunately, there are smaller medium head VS pumps, as well as larger high head VS pumps.
  • Aboveground and Inground pools over 20,000 gallons could use a medium head VS pump, like the MaxFlo VS, Superpump VS or the SuperFlo VS.
  • Larger pools, or pool/spa combos and pools with water features can use a high head VS pump, like the Ecostar or the IntelliFlo.
Remember when selecting a new pump to match hp, and pump type and flow rates. Use the Pump Flow Rate Charts, (see below) also known as Performance Data. This is based on a sample ‘feet of head’ of 30 or 40 feet. This is the only true way to compare pool pumps to each other.

How much Head or Resistance is in your system? That’s hard to calculate without a lot of math, but to compute resistance as measured in feet of head, you would need to know the resistance value of each length of pipe, every plumbing fitting, valve, pump, filter, heater, etc. But let’s keep this simple, shall we? If your pool plumbing is very simple, and your pump is fairly close to the pool, you may have 20-30 feet of head overall. If you have 3 or 4 lines coming into the pump, a large filter and maybe a heater, you may have 30-40 feet of head overall. If your pool is quite complicated, with lots of large pipes and extra equipment or water features, with a filter tucked away far from the pool, you may have 40-50 ft of head overall. If you can find the original info from the pool builder, the total resistance may be listed on the spec sheet.

As Americans, it's natural to want the big V-8 power plant, but a pump that is too powerful could actually prevent filtration while damaging the filter and heater. Pipes or fittings can separate, filter internals can collapse, and heaters can be stripped of copper.

When matching pumps to filters, check the Design Flow Rateof the filter on the filter label. The average flow for the pump you select (at a given level of resistance) should be within 10% of the pool filter's Design Flow Rate.
Remember also, that a smaller hp motor is going to draw fewer amps, which is going to cost less to operate. If you are careful to match up flow charts, you could actually reduce the hp required, while increasing the head of the pump. For instance, a 1/2 hp Whisperfloproduces about the same amount of flow as a 1-1/2 hp SuperPump, at a given resistance, or head. So, you could replace a Super Pump with a smaller Whisperflo pump; reducing your amp draw and cutting electrical expense in half.

When selecting a new pool pump, if you aren’t buying the same make/model, keep it close to the original specifications, and use the Pump Flow Charts. Most systems could handle a small increase in pump size, especially if you are replacing the filter with a larger one, but be careful to match pump flow rate with your filter’s design flow rate. And remember that the flow charts are assuming a clean filter, when in reality, your overall system resistance will increase as the filter pressure rises.

How do pool pumps work?
The water is pulled from the pool by a brass or plastic impeller that is shaft driven by an electric pump motor. On the way to the pump, the water is under a vacuum, which creates the suction. After the water leaves the impeller, the water is put under pressure, being pushed until it is released into the pool. The design of the impeller and impeller housing creates the suction required to lift water, and the pressure to force it through the filter. An air tight suction side is necessary (without air leaks) to create the vacuum to pull the water from the pool.
The electric motor is powered from a breaker on your electric panel (or fuse box), at 115 or 230 volts. Usually motors over 2 hp need 230V power to operate, and most smaller hp pumps convert to accept either 115 or 230 volts. Above ground pumps are often 115V only, and have a pump power cord for GFCI outlet power.
Electrical consumption will vary by pump, and manufacturers have been designing motors and pumps (the wet end) which are more efficient and consume much less energy than older pumps. Energy efficient motors draw fewer amps; the smaller the amperage draw of the motor, the less expensive it is to operate. On motors with reversible voltage (115V/230V), Amps is listed on a motor nameplate with two numbers, i.e. 16/8. The first number refers to the amps used to start the pump with 115V, and the lower number is when the motor is wired with 230V.

How long do motors last?
Pool pump motors typically last about 8-10 years before needing either rebuilding or replacing. Noisy, screeching front and/ or rear bearings will let you know when you need to do something. Read below for more information on noisy pool pumps.
Many people replace the entire pool pump, when only the motor is bad. The plastic parts of the pool pump, the front half, known as the wet end, do not generally wear-out or fail, and could last for the life of the pool, with an occasional replacement of small parts like the basket, pump lid o-ring or drain plugs.

Rebuilding a motor is a replacement of the bearings and shaft seal, which could be a wise direction if the motor is only a few years old. Pool pump motor bearings are sealed, and do not require lubrication or maintenance. There are several sizes of bearings and seals, with different motors using different sizes.
Pump motors are built for continuous duty, in the outdoors, but will last longer if shielded from weather and excess moisture. Removing a pump for winter storage can prevent the rust that develops between the stator and rotor on pumps left outside during periods of non-use.

Pool Pump Troubleshooting Guide: A guide to help you with some of the most common problems that can occur with pool pumps.

Leaking pump?
A very common problem is the threaded fitting carrying water out of the pump shrinking from heat and allowing water to drip, run and then spray. This can be replaced with a high temp fitting to prevent its reoccurrence. You’ll need to cut the pipe after the pump, replace the MTA (male threaded adapter) using an appropriate thread sealant, and reconnect the fitting to the pipe using some new pipe and a coupling or union.
Water may also leak from a worn out mechanical shaft seal. The pump seal is the separation between the wet end and the dry end (motor) of the pump, and allows the motor shaft to enter the pump, and spin freely without leaking water. Ozone and Salt resistant pump seals are made with materials that can better resist deterioration from salt water or ozone introduced in front of the pump.
A blown shaft seal is evident from water dripping down the back of the seal plate, and onto the ground, but should be distinguished from a leaking pipe fitting as described above or a leaking clamp band which holds the seal plate to the volute, or impeller housing. These leaks can also drip directly off the bottom of the pump, mimicking a leaking shaft seal.

Air in pump basket?
The pump is meant to operate air free, to create the necessary vacuum. After some time, you may notice air in the pump basket, especially if you have a clear lid to observe such things. Air in the pump will reduce filtering efficiency, allow dangerous air to build up in filter, and can prevent your pump from catching prime (being able to move water).
The problem is usually found in front of the pump, above-ground. Rarely do we have to look underground for the source of the air. The most common cause is the pump inlet fitting being loose, usually shrunken slightly from heat, or installed without thread sealant.
Air in the pump basket can be caused by something as simple as the water level being too low in the pool. Also, if the skimmer weir is stuck in the up position, it will block the water and cause the skimmer to drain and take in air. Also check that the pump basket lid is secured very tightly and the o-ring is lubricated with Teflon lube. Drain plugs without Teflon tape, or missing an o-ring (used on some pumps) will also cause the pump to draw air.

Locating an Air Leak
Make sure the strainer lid is on tight, with a clean, lubed o-ring. Also check that all drain plugs are tight. This void will always be before the impeller. After the impeller is what we call "the pressure side". Any leak or void after the impeller will leak water out. Any leak or void prior to the impeller (in front of the pump impeller) will draw air in when the pump is on. A pool pump will "pump" air if it can; it is the path of least resistance. So, your system needs to be almost airtight to run properly.

A good trick in locating an air leak is to shut off the motor when it's under full pumping head pressure, and look for water to spray back out of the void where the air was entering. You have to be quick to catch this spray-back, looking closely. If that didn't work, you can buy a Drain King at your local hardware store. This connects to a garden hose and puts the line under pressure. Push the Drain King into the skimmer, and close off other suction lines (skimmer and main drain valves). Remove the pump lid and use a plug or hold a tennis ball to plug up the pump entrance. Turn on the garden hose to allow pressure to build up in the lines before the pump basket and squirt out (or drip) at the source of the leak. You can also put the multiport valve on the Closed position, or close return side valves and pressure test the entire system in this way. If you find water leaking anywhere before the pump discharge pipe, that is the source of the air.

Make sure the water level in the pool is high enough, and that the skimmer weir is not stuck in the up position. Check that the incoming and outgoing valves are in the open position. If you suspect a clogged line, you can also use a Drain King to pressurize the line backwards from the skimmer towards the pump and remove leaf/debris obstructions.

Pump is not pumping water like usual?
If it’s not an air leak, (see above) it’s probably an obstruction. Could be a dirty pool filter, or closed valves. Check your skimmer baskets for heavy debris. Make sure the pump basket is clean and properly positioned, and that the pump lid is on very tight. Some types of pumps have a pump strainer basket that locks into place to prevent the basket from floating and blocking the entrance, or allowing debris to bypass the basket, and a clogged impeller.
When the pump basket is cracked it can also allow debris to clog the pump's impeller. If the pump basket is cracked or damaged, it should be replaced. To check the impeller, turn off the motor, remove the pump basket and reach into the volute and feel if it is clogged with debris. If you cannot feel for sure, you may need to remove the motor from the pump to properly inspect the impeller. Many times you need only remove a clamp band or 4 to 6 nuts, to separate the motor from the pump. More on cleaning a clogged pump impeller below.

Another way to rule out a clogged pump impeller, or an obstruction after the pump is to remove the pump lid, fill the pump with water, and turn on the pump for a few seconds. If you see the water get sucked down at least halfway, like a flushing toilet, you can assume that the impeller and pipes are clear. If the water just vibrates, or only goes down an inch or so, either the impeller is very clogged, or broken, or there is an obstruction after the pump, such as a dirty filter, closed valves or plugged lines.

Noisy pump motor?
Inside of your pump motor are a front bearing and a rear bearing, attached to the front and rear of the motor shaft (which is attached to the rotor). These bearings are sealed and cannot be re-packed or re-lubricated. They are replaced when they begin to scream and screech.
Bearings can become damaged when the pump has run dry and overheated, or if the pump is put under consistently heavy loads, or if the pump is dropped or something heavy falls on the motor. A local motor shop can replace the bearings for you, usually for around $100, or you can buy your own replacement bearings and replace them yourself, with the help of bearing pullers. Pump motor bearings are stamped with a 3 or 4 digit number that indicates their size. It can be hard to determine the correct bearings without actually opening up the motor, although most pump motors use 203 and/or 304 bearings.
To make sure it’s the bearings, remove the motor from the pump, and turn it on. If it still screeches while disconnected from the wet end of the pump - it is going to be the bearings. Rebuild it, with new bearings and shaft seal, or replace it with new motor and shaft seal. Or you can replace the entire pump.

A noisy pump can also mean cavitation. This sounds less like screeching and more like growling, like it’s gargling stones. This condition is caused by starving the pump for water. If possible, open more valves, or find the cause of the obstruction that is blocking water flow into the pump. It may be a clogged impeller, or if a new pump, it may be too powerful for your plumbing set-up.
Finally, noisy pumps can be the sound of components striking one another. The impeller can, on stub shaft models, come loose, and hit against the impeller housing. The internal fan can break and hit against the motor side. Both instances will resolve themselves. At 3450 rpm, it won't take long for the fan to wear down or the impeller to break.

Motor will not start or turn on
First check that you have power. Is the breaker on? Reset it by turning it all the way to the off position, and then back on again. Is the time-clock on? All switches on? Use an electric meter to be sure that voltage is correct, +/- 10%. With the power off, check that all electrical connections (where the power wires connect) are tight on the timeclock and on the other end on the motor terminal board. Check for visual evidence of corrosion or infestation of ants or bees. If comfortable doing so, you can turn the power on, and using an AC voltage test meter, verify that there is power going all the way to the motor. If there is proper power coming into the motor, as tested on the terminal board, but no noise whatsoever, the motor may have become shorted across its windings. Time for a new motor if this occurs.

Motor hums but will not start
If this is the first start up after a long time off, such as during spring opening, there may be rust built up between the stator and rotor, inside the motor – this we call a ‘frozen’ motor. If you have an open volute, with visual access to the shaft, use straight pliers to move the shaft back and forth, until it spins free. If you cannot see the shaft, as is the case with most pool pumps, access it through the rear of the motor, placing a wrench on the shaft to turn it back and forth to break the rust that has formed inside the motor. You will need to loosen either the capacitor (9 o’clock) or thermal overload switch (12 o’clock) to be able to get a wrench (usually 7/16”) on the slotted end of the motor shaft.

Another rare cause is that the impeller may be clogged with so much debris that it stops the motor shaft from turning. Turn off the power, and spin the motor shaft. If it won't turn freely, remove the motor from the pump and clean the impeller. If the shaft spins freely, check the capacitor. If it is a stub shaft type motor (with non-threaded shafts used on older brass pumps), check that the impeller is not hitting the impeller housing.

The start capacitor is the black cylinder on the back of the motor, which gives the motor the extra oomph it needs to start up. Check the capacitor for white residue or oily discharge or for bulging or cracking. Sometimes even a fine looking capacitor can be bad.
Capacitors can be tested with an Ohm meter. First remove the leads with pliers, then discharge any stored power by touching two opposite terminals at the same time with an insulated screwdriver. If there is stored power it may make a popping sound. Set your meter to Ohms, on the 1K scale, and touch the leads to two terminals. A good capacitor will slowly rise on the meter, while a dead capacitor will remain at zero. Replace with a new capacitor of the same microfarad rating. This is printed on the capacitor, for example 161-193 MFD, which is the capacitor size used for ¾ - 1 hp motors.
Finally, low voltage can be a cause of a humming but not starting motor. New motors are wired 220 volts, so if you hook it up to 110 volts, it will only hum, or cycle. Or perhaps one of the power leads is loose, corroded or shorted. Check with a Multimeter to verify the correct voltage, with a variance of 10% allowed, either higher or lower.

Motor Cycling
When pool motors run for a short while, shuts itself off, and turns itself back on later, it may be overheating. Normal motor temperature is over 140 degrees, so all motors run hot to the touch. But a cycling motor may indicate that the thermal overload is kicking it off. If this motor was just replaced, make sure that the electrical supply connections are correct and the wire size is correct for the voltage it is carrying. Low voltage can also cause overheating. Inadequate ventilation can cause overheating, so make sure that the air vents are unobstructed, and clear away any mulch or leaves. Usually, old motors that suddenly begin to overheat will need to be replaced. They usually have a short inside, across the windings, and motors are just not rewound anymore like they were in the old days.

Plumbing in a new pump motor...
Cut the pipes going into the front of the existing pump, and the pipe coming out of the top. Important: Choose your cut location so as to allow room on either side of the cut to glue on a repair coupling or union. Remove the wires and the conduit adapter from the rear of the motor. Remove the MTA fittings threaded into the front and top of the old pump. Using Teflon tape and perhaps also silicone sealant, thread in the fittings you removed from the old pump, unless you suspect that they have shrunk. Note: Do Not Over-tighten; turn only 1-1/2 turns past hand tight. Using pump unions or simple slip x slip couplings, reconnect the pipes you cut. On PVC fittings, use a PVC primer and good, fresh PVC glue for all plumbing, and be sure to use pressure fittings, which have deeper sockets than drain fittings.

Wiring up a new pump motor...
There is a small wiring diagram printed on the motor label for your reference. First, screw in the conduit adapter onto the back of the motor. Remove it from from the old pump and screw into the 3/4" threaded hole where the wires enter the back of the motor. Remove the back of the motor and run the wires in through the adapter, and tighten down the threaded nut to secure the wires and keep out moisture and insects. After running the wires into the motor, on the right side, a terminal board that has 2 brass screws for clamping down the 2 wires (lines) coming in. It doesn't matter which wire goes to which screw, L1 or L2. Above the terminal board, there is a green screw that is for clamping down the ground wire.
All pump motors which are 115/230V, or ‘reversible’, are wired to receive 230 Volts from the factory. This is to prevent damage to the motor by attaching 230V to a motor set to accept only 115V. A 230V motor is set up to accept 2 lines (wires) carrying 115 Volts each. So, you need to know if you have 115 Volts coming in, or if it's 230 Volts. Usually (but not always) 230 Volt service will have 2 wires of the same color, (and one green ground wire), while 115 Volt service will have perhaps one red (hot), one white (neutral), and one green. You should use a meter to be sure, or you can look at the circuit breaker. If 2 wires come off of one breaker, then you have 230 Volts. If one wire is connected to a breaker, and the other to the 'neutral' Buss bar, then it is 115 Volt service. Or look at the voltage plate on the old motor and see how it was hooked up. Does the terminal board wiring (not your power wires, but the other wires attached) match the Low Voltage diagram (115 Volt), or match the high voltage diagram (230 Volt)?
If you have 230 Volt service, hook up the wires coming into the motor to the brass terminals in the same way as described above. If you have 115 Volt service, follow the instructions on the motor label to switch the motor to receive 115 Volt. This is a very easy switch of only one wire. Again, a reversible motor comes factory wired for 230 Volt. If you are connecting 115 Volts to it, then switch the motor first. Maybe you ordered a 115V motor? Check the motor label before wiring, as putting 230 Volts into a 115 Volt motor can damage the windings, and likely kill the motor.
Replacing the motor (not the plastic wet end, just the motor)
Having learned how to remove and break down a pump and motor in the previous sections, replacing any of the components is simply a matter of disassembling the pump down to the component that needs replacement, getting a replacement part, and reassembling the unit. Schematic parts images, or expanded diagrams found in our pump parts department, are very helpful in identifying individual pump parts.
Sometimes the motor will trip the circuit breaker when you try to start it. If this happens it could mean there is something wrong with the motor however, it can also be loose wiring, bad wiring, or even a bad breaker, they do wear out, especially if used often as the pump switch, or if the amperage rating is very close to the pump max load amp draw.
To replace a Threaded Shaft type of pool pump motor, here is the procedure:
  1. Break down the pump by separating the volute or seal plate, and pull the motor back out of the pump. Shut off power and remove the wires from the back of the motor.
  2. Moving the capacitor out of the way, use a 7/16” wrench to hold the motor shaft stationary, while you spin off the impeller in a counter clockwise direction. Use Channel type pliers to gently assist if needed or a strap wrench.
  3. With the impeller removed, remove the 4 bolts that hold the motor onto the seal plate. Remove the seal plate and any collars connecting to motor to the seal plate.
  4. Remove the ‘donut’ seal half of the impeller that is pressed into the seal plate with a flat head screwdriver. Clean up any grease or rough edges, and press the new donut into place, using a piece of paper to keep the ceramic seal face clean.
  5. Attach the pump seal plate to the new motor, tightening the four bolts snugly. Replace the spring half of the shaft seal onto the impeller, in the same orientation as removed.
  6. Attach impeller wear ring (small side toward impeller) and diffuser over the impeller, if applicable.
  7. Wire up the new motor (as described above), and reassemble the pump, making sure the seal plate o-ring is in place. Tighten the clamp band or bolts very tightly.
  8. Fill with water, replace lid, open valves, restore power and fire it up!
To replace a Keyed Shaft motor (old brass pumps):
  1. Break down the pump as described in the section on changing a seal. Remove the shaft extension by removing the Allen-Head set screws and pulling the extender off the motor shaft. Usually requires penetrating oil and some persuasion. Use your large flat-blade screwdriver to pry the extender away from the motor body. Sometimes corrosion will eat away at the setscrews and extender - if it is too tough to remove, replace it.
  2. Before sliding the shaft extender on the new motor, clean the motor shaft with a fine emery cloth. Apply a light coat of silicone lube to the shaft. When you put the extender on the motor shaft, the setscrews go into a groove that runs along the shaft.
  3. Slide the shaft extender in place, lining up the set screws along the channel, but do not tighten the set screws. When you have reassembled the bracket and seal plate, seal, and impeller, adjust the impeller to just barely clear the seal plate face, then tighten the set screws. Be sure the impeller is screwed tightly onto the shaft extender before making this adjustment.
  4. Follow wiring instructions above, in previous section on installing new pumps.
  5. Bolt the motor bracket to the impeller housing, fill with water and test briefly.
Pump Lubrication
A lot of air in the pump or loss of prime problems can be due to lack of lubrication on the pump lid o-ring. Lubricants like Magic Lube (Teflon based) or Jack's 327 Lube are always a great choice. Never use a petroleum based product (i.e. Vaseline) for lubrication on o-rings, which can damage all types of pool o-ring rubber. Replace pump o-rings if you see cracks, splits, or pinch marks, or if they become distended (enlarged) or flattened, or if they no longer make a good seal, despite efforts to reseat the gasket.

Replacing the Mechanical Shaft Seal
All pumps have seals to prevent water from leaking out along the motor shaft. When these wear out due to salt or ozone damage, overheating, vibration or a sudden change in water pressure, resulting in a water hammer effect - you will need to replace your pump shaft seal. For saltwater pools or pool that introduce ozone or chlorine in front of the pump, use an Ozone/Salt pump seal, to resist damage to the seal.
The first thing to do is to turn off the electricity to the motor at the circuit breaker.
  1. To access this seal for replacement, remove the bolts or clamp band that hold the pump halves together, (not the 4 bolts that hold the motor onto the seal plate). It is not necessary to remove the entire pump (wet end) from the plumbing system.
  2. Grasp the motor and pull it and the bracket or seal plate away from the pump volute. You may need to wiggle it slightly as you pull back to help separate the motor from the pump.
  3. Take a 7/16” wrench and hold the shaft at the rear, to prevent it from turning. You will have to loosen the capacitor (on the left) or the high limit (at the top), to gain access to the back of the motor shaft, which is slotted to accept an open end wrench.
  4. Unscrew the impeller from the shaft counter-clockwise, using large channel pliers or a strap wrench. Wrap a rag over the face of the impeller to avoid damage.
  5. Remove the four bolts that hold the bracket or seal plate to the motor. If needed, use a hammer to gently tap a stuck bracket away from the motor.
  6. Remove both halves of the old seal. Notice how each half is installed so you get the new one back in the same way. One half is on the back of the impeller and is easily popped off with a flat-blade screwdriver. The other half is pushed into the seal plate and motor bracket unit. Lay the bracket on your workbench with the seal on the bottom. You will see the back of the seal through the hole in the seal plate. Using the flat-blade screwdriver once again, put the tip on the back of the seal and tap it with a hammer. It will pop out easily.
  7. Install the new seal. Clean out the seal plate and impeller where you have just removed the old seal. Install each half of the seal the same way you removed the old one, white ceramic of one half facing the glazed carbon ridge of the other half. Use care in installing not to damage, nick or soil the face of either seal half.
Paper Gaskets. When you break apart an old brass pump, the old gasket usually won't reseal. Clean the old gasket off of the seal plate and volute. Scrape it clean if needed with a flat blade screwdriver. Now reassemble the pump the same way you took it apart, placing a new gasket between the pump halves. Plastic pumps use a rubber o-ring, which will almost always reseal again properly.

A fresh paper gasket might leak for a few minutes until it becomes wet and swells to fill all the gaps, but it should stop leaking after a short time. If your job does leak, take it apart and go over each step again, making sure the seal halves are seated all the way and that there is no corrosion or debris left in the impeller or seal plate that might prevent the new seal from seating completely. You may add some Blue RTV siliconesealant to help a paper gasket.

On plastic pool pumps, the clamp or bolts are removed to disassemble the pump, and you will usually find a diffuser or impeller shroud covering the impeller. After removing this, you can grip the impeller with your hand and twist it off, but you’ll need to stop the shaft from spinning as you twist off the impeller. There are air vents in the motor on the end closest to the pump itself. Look in and you will see the motor shaft. Place a flat-blade screwdriver in one of the air vents and wedge it against the shaft to keep it from turning.
If the impeller won’t twist off easily, and you don’t want to risk breaking the fan blades, you can remove the rear motor cover and look inside as you twist the impeller. You will see the back end of the shaft, with the centrifugal switch attached (AO Smith motors). Since this switch is fragile, you must remove it (one center screw) to access the slotted screw in the back end of the shaft. Place the screwdriver in this screw to keep the shaft from turning as you remove the impeller. Or use a 7/16" wrench on the back of the shaft, which is usually slotted to accept an open end wrench.

Instead of a gasket, plastic pool pumps use an o-ring. Clean this and lubricate it before reassembly. If it has stretched and it seems like there is too much o-ring for the channel in the volute, soak the gasket in ice water for a few minutes to make it shrink. If that’s not enough, you can razor knife off a ¼” or so, and superglue the dry and straight ends. Pump Rebuild Kitsinclude all of the seals, gasket and o-rings used on 22 of the most popular pool pumps.

Some pumps use a plastic impeller that holds the round seal half in place, instead of the spring half, like most pumps. If the pump has run dry and overheated, this impeller can warp or melt and the seal will not fit tightly. The only solution is to replace the impeller. This is a common problem with automatic cleaner pumps, which are not self-priming.
Remember to use only non-hardening silicone lube like Magic Lube on all pool and spa o-rings and valves. Don’t use Vaseline or other lubricants that are made of petroleum, which eat away at rubber o-rings.

You may notice that the shaft seal has a larger inner diameter than the motor shaft. This is because the shaft seal doesn’t actually touch the shaft. If it did, it would burn up in seconds, at 3450 RPM. The sealing is made not around the shaft, but between the seal plate and the impeller, or between the two seal halves.

Clogged Pump Impeller?
When your pressure is high, your filter is dirty, right? When your pressure is lower than normal, however, your pump basket is dirty. If the basket is clean, yet pressure and flow is still low or surging, you may have an air problem or the impeller may be clogged. Something prior to the filter is obstructed. A clogged impeller will still pump water, but only about half-speed. If you have a clear pump lid, you will notice abnormally slow swirling of the water, or the basket may not fill fully with water.
To unclog an impeller follow these steps:
  • Shut off power, remove motor and seal plate from pump. Sometimes this is one clamp that holds the motor to the pump, or some pumps have 6 bolts to remove.
  • Stand motor on its end cap, remove any diffuser or impeller shroud, and using needle nose pliers or a thin screwdriver, remove the clog. Run some heavy wire through the vanes of the impeller to ream out debris, pushing it back towards the center of the impeller, where you can pick it out.
  • Reassemble pump snugly and tightly. Fill pump pot with water and restart pump. Filter pressure then should rise to the normal range.
Replacement of a pool filter pump:
When replacing your motor, you may opt to install a high efficiency pump (one that is sized correctly for your filter). This can reduce energy consumption and/or increase skimmer suction to make the pool easier to keep clean. As mentioned earlier, the best pump replacement is likely the same exact pump as the one prescribed by the original builder, who we assume did the correct calculations. However, pool systems are dynamic, always changing with new equipment added or subtracted, and a previous owner may have installed a pump that is too large (or too small, but probably too large).

A great option for many pools nowadays when faced with a pump replacement is to upgrade to a Variable Speed pump. They are simple to wire, include on-board timer, controls, diagnostics and status. VS pumps allow you to run the pump at different speeds, and save up to 70% on energy bills. The quiet running TEFC permanent magnet motor is cool to the touch and is more durable than traditional motors.
The idea of a VS pump is that you run the pump longer each day, perhaps 20 hrs/day, but at low speeds, with one or two 3-6 hour high speed periods for heating, chlorinating and cleaning. As mentioned above, IntelliFlo and EcoStar are high flow VS pumps for large pools with many features. Hayward and Pentair also produce several lower priced VS pumps built with common pump bodies, to retrofit to Maxepro, Superpump or Whisperflo pumps.
For more information on how to size and select the correct replacement pool pump, or help with new pump installation and pump wiring, scroll back up the page, it’s near the top. If you are still stumped, give us a call!

 Replace or rebuild your pump motor?
For most all rebuilds of a pump motor, expect charges of $100-$150 to have a motor shop rebuild a motor (new bearings and shaft seal, full test). Motor repair shops offer drop off / pick up service, in 1-2 days turnaround usually. Theoretically, the motor will last another eight years, but the warranty is only 90 days. The warranty on the new motor is 2 - 3 years for most manufacturers. Whether rebuilding or replacing the motor, the Shaft Sealshould also be replaced, or you can buy Pump Go-Kits, which include the Seal and all of the O-rings for a particular pool pump (typically includes the pump lid, diffuser, and seal plate o-rings).
If your motor is fairly new (less than 5 years old), it may be worthwhile to rebuild a motor with new bearings and a shaft seal. However, motors are much more than just bearings and seals, and another repair of a different sort may be just around the corner, for an older motor.

Booster Pumps
You may have an automatic pool cleaner (Polaris) that requires a booster pump. It looks different from your filter pump because it doesn't have a strainer basket. This is because it’s pumping strained and filtered water, and there should be no debris to worry about. All else is the same as a regular pool pump; however it should last longer if it's being used only a few hours per day.

Never operate the booster pump without the filter operating and providing it a constant flow of water. If you have time clocks, synchronize them to ensure this doesn't happen. Otherwise, you will probably burn up the shaft seal, and possibly damage the bearings, or need to visit our booster pump motors page.

Blower Motors
If your pool has an attached spa, you may have a forced air blower motor sticking up above water level. This is connected into the spa jets (return lines) to provide turbulence and air therapy.
If your blower motor is not working or is very noisy, it may need rebuilding or replacing. Warranties and prices are very similar to filter motors. Before calling for service on any motor, check that switches on the motor are on, breakers are on, spa side or indoor remote controls are on, and the timer is on.