Mechanical Shaft Seal - How to Replace the Shaft Seal on Your Pool Filter Pump

All swimming pool and spa filtration systems, involve the use of several pieces of equipment. One of the most important being your spa or swimming pool filter pump. A mechanical shaft seal is one of the key components in the design of these pumps. The job of a mechanical seal is the prevention of water leaks along the pump's motor shaft.

Damage to the seals of pool and spa pumps, takes place because of overheating, vibration, and a sudden change in water pressure. There are some cases where dirt get trapped between the faces of the seal. This can cause damage to the seal as well which results in a leak. Once you develop a leak on you pump, it will only get worst; thus, the shaft seal has to be replace.

Steps to successfully replacing your pump shaft seal

Before the repairs to any swimming pool pump can begin, you have to gather the necessary tools and replacement parts needed to complete the job. Tools and resources needed include:

• A pair of pliers.
• A good ratchet set.
• A small impeller wrench.
• A rubber hammer or mall.
• A set of flat screw drivers.
• Some emery cloth sand paper.
• Silicone lubricant.
• A new mechanical shaft seal assembly. Ensure that you have the correct seal model for your pump model. You can do this by checking your owner's manual or supplier of your pool pump.
• A replacement gasket for the pump housing.
• Anti-seize. For coating the threads of the motor shaft.

Replacing your pump shaft mechanical seal

As a rule of thumb, always abide by all safety instructions whenever servicing any type of electrical equipment. Failure to do so can result in serious injuries or death to yourself or others.

• Before you begin the repairs to your pool filter pump, you have to disconnect all electrical power sources. Make sure that you lock out and tag the main circuit breaker. This is an added safety precaution, that will prevent any injuries due to someone accidentally turning the breaker on.
• Close the valves on both the suction and discharge sides of the pump.
• To access the bad mechanical seal on your pool pump, you have to remove the four hex head bolts. These are the four bolts that connect the motor and impeller assembly to the pump housing.
• Hold the motor firmly with both hands and wiggle it from side to side slightly. This will allow you to successfully pull the motor and its bracket assembly away from the pump housing.
• Using your pliers or crescent wrench, hold the extended end of the motor shaft (back end). This will prevent the motor shaft from moving.
• Now take your impeller wrench and unscrew the impeller from the pump shaft. If you don't have an impeller wrench handy, you can place an old rag over the impeller and unscrew it by hand. The rag will help in preventing you from cutting yourself on the impeller's sharp edges. There is also another option but it is a last resort. Use one of your against the impeller and gently tap it with your rubber mall. Still be very careful not to crack or damage the impeller.
• The seal plate now has to be removed from the pump motor. This is accomplish by removing the four small screws that hold it in place. Once the screws are removed, a gently tap will free the seal plate from the motor.
• Now before you remove the mechanical shaft seal, please take notice of how it is installed originally. This will help you in the installation of the new pump shaft seal.
• Now use a small flat screw drive to help in the removal of the rotating part of the seal component.
• The stationary portion of the seal is in the recess on the seal plate located on the motor bracket. To remove it, you have to turn the seal plate over. The stationary portion on the seal is now facing down. Place the tip of a flat screw driver on the back of the seal and gently tap it out.
• Use the emery cloth and a little water to clean the shaft/sleeve of the motor and the seal recess in the seal plate.
• Place a small amount of silicone lubricant on both the motor shaft and in the mechanical seal recess. This lubrication helps the seal assembly to slide into place a little easier. Make sure that you install both halves of the seal assembly in the same manner as the original. The white ceramic portion of the seal with the black rubber cup, goes into the seal plate. The glass finish MUST be facing you.
• The other portion of the mechanical shaft seal (rotating part with the spring) goes onto the motor shaft. This is only after the motor bracket is bolted back in place. You must use extreme care here because you don't want to damage, scratch or dirty the faces of your new mechanical seal.
• Check the pump gasket and if it is damaged in any way, replace it. Now if your pool pump carries a paper gasket (centrifugal pumps), you will definitely have to replace it. Truth be told! Whenever you disassemble a pump, the original gasket usually fails to reseal. Before installing your new pump head gasket, you must remove any trace of the old one. This will ensure proper seating of the new; thus, providing a proper seal.
• If you have to replace the pump head gasket, insert the new one between the two halves of your pump. Now re-assemble your swimming pool pump in the reverse order that you disassembled it.
• Lastly, open the valves on your pump's suction and discharge lines. Restore the electrical power supply and start it up. Check for any signs of leaks. There are some instances where a paper gasket is used, that a small leak may be evident; however, once the gasket is wet it will create a proper seal. In some cases, one or two more turns on the pump bolts is required. Nevertheless, once you follow these instructions your pump repairs will be a success.

Ordinarily the manufacturers of spa and swimming pool pumps will advise against you doing your own pump repairs. This is so that you keep your warranty and avoid any injuries. Nonetheless if your warranty is up and you are a little short on cash, I say go for it and do your own repairs. But always use your judgment and always exercise safety first. Manufacturers also prefer persons that are qualified to work on their products, to do so.