Your pool pump's shaft seal plays an important role in protecting the motor. It sits between the motor and the impeller blade in the vacuum chamber, and its purpose is to prevent water from traveling up the shaft towards the motor. If your shaft seal fails and starts to leak water, your motor bearings can quickly be damaged — this puts more stress on your motor and can cause it to fail early.
You can generally tell that your shaft seal is leaking by looking underneath your pool pump's motor. When the pump is turned on, a leaky shaft seal will cause water to slowly drip from underneath the motor. If you notice a leak like this, it's important to replace the shaft seal as soon as you can. Thankfully, shaft seal assemblies are inexpensive and the replacement job is fairly easy to accomplish. Read on to find out how to do it.
Ensure the Pump's Power and Water Are Turned Off
Turn off power to your pool pump at your circuit box, and then close both water valves next to your pool pump. You should never work on your pump when it's still powered.
After you turn off the power, you'll need to discharge the residual power in your pool pump's capacitor. Unscrew the very back end of your motor assembly, and then touch the tip of a flathead screwdriver to the two terminals on the capacitor in order to bridge them. This releases the remaining charge.
Disassemble Your Motor
Next, you'll need to disassemble the motor assembly. The motor is usually connected to the rest of the pump using bolts, which can be removed using your socket wrench. Detach the motor from the rest of the pump and pull it off.
Now you'll need to remove the impeller to access the shaft seal. At the very back end of your motor, you'll see the shaft. You'll need to stabilize this shaft while you unscrew the impeller by hand. Many pool pump shafts have an indentation in the shaft that you can slide a flathead screwdriver into in order to keep it from rotating. For other pool pumps, you'll need to hold the shaft steady by using a wrench.
Once you've unscrewed the impeller, you can remove the seal plate behind it. After you've done all that, you can finally replace the shaft seal.
Replace the Shaft Seal
Remove your replacement shaft seal parts from their package using a clean microfiber cloth. Take care not to touch them with your hands, because you'll damage them. You need to replace the disc in the center of the seal plate and the disc on the impeller.
All you need to do here is just replace the old discs with the new ones. You may have to pry the old ones off with a screwdriver if they're stuck. Make sure the replacements are facing in the same direction as the parts they replaced.
Reassemble Your Motor
Now all that's left is to reassemble your motor. Put the seal plate back on, stabilize the shaft in the same way that you did before, and then screw the impeller onto the shaft by hand. Reattach the motor to the rest of your pool pump by screwing the bolts back in with a socket wrench, and then replace the backplate of the motor assembly. Before you turn your pool pump back on, make sure there's water in its bucket — running the motor dry will quickly damage your brand-new shaft seal.
With all that done, you've successfully replaced your pool pump's shaft seal. While this replacement job is fairly easy, it's also inexpensive when you have it done by a pool repair professional — if you don't have the necessary tools or if you have a very old motor with significant mineral buildup that makes it difficult to disassemble, you may want to consider simply calling a pool repair service and having the replacement performed for you.