How To Replace A Pool Pump Motor

Hello ePoolSupply supporters! Today I wanted to talk about how to replace a pool pump motor. In this blog, I will be talking about replacing a WhisperFlo pump motor with a square flange. Please note that not all pumps use the same motor. Certain pumps require round flanges and others use square flange motors. If you are uncomfortable or need any help with replacing a pool pump motor please call for a pool professional to come out and help.

If you think you need your motor replaced but are not sure then keep on reading! Your pool pump is essential to keeping your pool clean and functional. When you hear a strange noise from the pump you might not be sure what it is or what to do. The first step is to check the condition of the pump. You shouldn't see any dry or cracked housing around the edges. There should be no rust, discoloration, or leaks. If you see any of this then it may be time to replace the pump. Below I have attached a Youtube video on how to replace your pool pump. If your pump is in good shape then it is time to move on to the motor. To check if your motor is the problem, keep the pump housing open and listen closely to the motor. You should be listening for grinding, screeching, humming, pops, and clicks. If you hear no sound at all then it probably means the motor is dead. If you hear any strange noise coming from your motor then it is time to be replaced. Keep on reading to learn the steps on how to replace a motor with a square flange.


  1. Make sure you order the correct motor for your pump. You can find the part number on your old motor’s information tag.
  2. Replace the shaft seal. When replacing the motor, it is recommended to replace the shaft seal to prevent any leaks and to make sure it will have a stronger seal. There are kits you can buy that have the shaft seal and the o-rings the part number is 356198.
  3. Turn the breaker off to the pump.
  4. Start removing the six bolts that hold the seal plate and housing together.
  5. Remove the wiring and conduit from the end of the motor. Take a picture of how the wires are connected as they will need to be connected the same way into the new motor.
  6. Remove the diffuser by removing the two small socket head cap screws.
  7. Now you will see the impeller and there is a screw in the center. You will remove that screw by turning to the right as it is an anti-spin reverse-threaded screw. The impeller can now be removed by spinning it to the left.
  8. Remove the access cover on the opposite side of the motor to reveal the other end of the shaft motor. Spin the impeller with your hand and you will see this shaft move on the other end. Hold the shaft with pliers or channel locks so you can spin the impeller off.
  9. With the impeller off, remove the four bolts that hold the motor to the seal plate. Once the seal plate is removed, you will see two halves of the shaft seal. One half is inside the impeller and the other half is inside the seal plate. You can use a flathead screwdriver to pry out half of the impeller and pop the other half out of the seal plate.

Now that you have removed everything to get to the motor, it is time to start assembling the removed parts to the new motor.

  1. Make sure the breaker is still off.
  2. Insert the new shaft seal into the impeller and seal plate just as the old one was installed. It is best to apply a thin layer of lube to the seal plate. You can easily drop the seal in and set it in place with your fingers with the seal plate flat. Then use a 1-inch PVC coupling to seal evenly and fully by placing it on the seal and then gently tapping it in with a rubber mallet.
  3. Bolt the seal plate to the new motor with the previously removed four bolts, it is important to not over-tighten.
  4. Screw the impeller back onto the motor shaft then screw in the anti-spin reverse-threaded screw.
  5. Attach the diffuser over the impeller back to the seal plate with the two previously removed socket head cap screws.
  6. Connect the electrical wires to the new motor just as they were connected to the old motor. You should have taken a picture of how they were originally.
  7. Now you can slide the completed assembly with the new motor back into the housing and secure it with the six bolts previously removed in the first step of breaking down the pump. It is important to not over-tighten.
  8. Remove the pump pot lid and fill it with water using a garden hose. This will help prime the pump.
  9. Turn the breaker back on and turn the pump on. Check for any issues to make sure all is working properly.

In conclusion, If you are uncomfortable or need any help with replacing a pool pump motor please call for a pool professional to come out and help. If you have any questions please contact us.

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