Mechanical Seal Installation For Centrifugal Pool Pumps

by Pool Builders on 02-26-2010 in Articles

Your swimming pool pump is one of the key component in your pool filtration system; however, there will be times when it will require some major repairs. One of the more common repairs done on a pool or spa pump is the replacement of the mechanical seal. This is one of those repairs that could cost you a pile of money. A more cost effective way of doing this repair, is learning how to do it yourself.

Purpose of the pump seal

All centrifugal pumps have a shaft seal installed. The purpose of these shaft seals is to stop the water or liquid that is pumped from leaking along the shaft. Understanding mechanical pump seal designs is very important. It teaches you how a basic mechanical seal works. So how do I change the seal on my swimming pool pump? Please understand! Some pump seals are installed a little differently in some swimming pool and spa pumps; however, the principle purpose of the seal is the same. And that is to stop leaks.

Mechanical seal repair

Before you begin your seal repair, you have to kill all electrical power source to the pump motor. Once the power source is disconnected, you have to lock out the main circuit breaker. This will prevent any accidental switching of the power.

Tools and resources needed for the seal replacement

Replacement of pool pump mechanical seals require some basic tools and parts for the job. These are items such as:

  • An open end wrench set as well as a good ratchet set.
  • A new mechanical seal for the new install.
  • A set of flat screw drivers.
  • Emery cloth (sand paper).
  • A bearing puller. To help remove the pump impeller.
  • A new replacement impeller. This will only be needed if the one that is on the pump needs replacing.
  • A new volute paper gasket. You will not be able to re-use the original one.
  • Hammer or heavy duty rubber mall.
Now that you have the tools and parts needed for the repairs, you can proceed.
Steps to a successful shaft seal change
  • Double check that your main circuit breaker is off and locked out.
  • Close the valves on both the discharge and suction side of your pool pump.
  • Loose the bolts that is holding the motor in place on its base plate.
  • Back the motor away from the pump section and secure the flex coupling.
  • Loose the drain plug on the volute housing to release and drain the pump housing.
  • Loose the bolts that connect the volute cover plate to the volute.
  • Loose the pump stand blots and separate the cover plate from the volute. Using the back away bolts. You may need to use your hammer to lightly tap the cover plate away.
  • Using your ratchet, remove the bolt that is holding the impeller in place.
  • Pull the impeller off the pump shaft. If it is hard to remove, use the bearing puller to aid in its removal. Inspect the impeller for wear and tear. This will determine if it has to be replace. If the impeller is in good condition, use care in its removal. You don't want to crack or bend the impeller.
  • Once the impeller is removed, remove its holding key from the slot on the shaft.
  • Using your screw driver, remove the spring and the rotating component of the old seal from the extended end of the pump shaft.
  • Next, remove the ceramic (stationary component of the seal) from the seal recess in the volute cover plate. To do this, you have to turn the cover plate over and gently tap the damaged seal out.
  • With the old mechanical seal completely removed, inspect the pump shaft and sleeve along with the seal recess for damage. There are times when you may have to replace the pump shaft but that is another repair within itself.
  • Clean the seal recess with emery cloth and water and dry thoroughly. Clean the extended end of the shaft and sleeve to remove all the rust and dirt.
  • Open the new mechanical shaft seal, be careful not to touch the polished face of the seal faces. Also do not rest the mechanical seal on down on your work table. The faces of the pump seal is easily scratched and once this happens you seal is not longer useful. It will leak.
  • Install the stationary part (ceramic portion with the black rubber cup) of the seal into the volute cover plate. Remember it has to installed in exact manner as the old one. Also check and make sure that this part of the seal is inserted all the way into the seal recess on the cover plate.
  • Now slide the rotating part of the pump shaft seal over the extended end of the shaft. Carefully push it down towards the polished face of the ceramic piece in the volute cover plate.
  • Insert the impeller key into its slot on the pump shaft.
  • Position the impeller over the shaft, aligning the slot of the impeller with the key and slide it into place.
  • Replace the impeller washer and blot and tighten.

Now you are ready to re-assembly your pool centrifugal pump.
But first you need to replace the volute paper gasket and secure it in place with a little RTV silicone sealant. Always use non-hardening silicone lube on all your swimming pool and spa pump repairs. DO NOT use Vaseline or any other lubricants made with petroleum. They can cause problems by eating away some paper and plastic gaskets. Once the paper gasket is in place, you can begin your re-assembling of your pump.

  • Slide the volute cover plate assembly into the volute of the pump housing.
  • Line up the holes for the cover bolts.
  • Insert the bolts and tightened in a crisscross pattern. This helps the cover plate assembly to slide into place without the impeller binding to the walls of the volute. housing.
  • Re-insert the flex coupling into its hub and slide the motor back into place; thus aligning the hub on the motor to the end of the flex coupling.
  • Insert the holding bolts for the motor. Align the pump and motor to ensure proper operation. Failure to do this will cause your mechanical seal to fail again.
  • Open the valves to both the discharge and the suction side of your pool pump.
  • Restore the electrical power supply to the pump motor.
  • Run the pump system and check for any leaks.

Congratulations! You just saved yourself a pile of money, by replacing the mechanical seal on your pool pump. I invite you to visit my site, where you will find a wealth of information that will help you manage your pool/spa correctly. Just click the link in the resource box.

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