Replacing a Pool Pump Motor

by Rob Cox, June 22, 2010

10 Steps to Replacing your own swimming pool pump motor


hayward superpump schematic diagram

1. Obtain your materials: You will need a pool pump motor of course. It must be the same horsepower (hp) as your previous one, to match up correctly to the hp-rated impeller. You will also want to replace the mechanical shaft seal. You can buy the seal separately, or you can purchase a GO-KIT which contains all of the gaskets, seal and o-rings for a particular pool pump. You need not replace all the gaskets or o-rings when you replace a motor, unless they are suffering from dry-rot. If the rubber o-rings look good, just use some magic lube or other silicone based lubricant.

2. Pull the Motor: Shut the power off at the circuit breaker. If your system is below water level, close incoming valves. Usually there is a clamp band that connects the seal plate (the plate that the seal fits into) to the volute, or impeller housing. Sometimes, the seal plate is connected to the volute with 4 or 6 bolts, as is the case for the Superpump shown above. When pulling a motor out of the housing or volute, the motor will remove with a seal plate attached. You may need to pry gently with a flathead screwdriver to separate the two halves, after removing the clamp or the bolts. Grab the motor firmly and pull it straight back.

3. Remove the Wiring: Most pumps will have three wires. For a 220V motor, both black and white (or red) wires will be "hot" - so make sure that the power is off at the breaker. There will also be a green ground wire connected to green screw head. Remove all 3 wires, and remove the conduit connector from the old motor and screw it in the same place on the new motor. If you have a two speed motor, you will have a 4th wire, the low speed wire. If you have 4 wires, you may want to label them as you remove them.

4. Remove the Diffuser: Also known as an impeller shroud, or # 18 in the picture above. Sometimes these simply pull off, and sometimes screw removal is required. Remove and set aside, keeping tabs on the diffuser gasket, #3 in the picture above.

5. Remove the Impeller: The trick here is to secure the shaft of the motor, so that you can spin off the impeller. It is regular threaded, counter-clockwise to remove. If you have an older pump, with an open bracket, where you can see the shaft, then you can grab the shaft at this point, with vice grips or channel locks, hold it tight, while spinning off the impeller. Most modern pumps now have no access to the shaft, so in most cases, the easiest way to secure the shaft is to open up the back of the motor, loosen the capacitor (black cylinder) so you can move it out of the way, and put a 1/2" open end wrench on the end of the shaft. You will find the shaft slotted to accept the wrench. The centrifugal switch will be on the end of the shaft, you will be inserting the wrench behind the switch, and then simply propping the wrench handle up against the motor body to hold the shaft stationary, while you grab the impeller firmly and turn counter-clockwise to remove. If too difficult to remove by hand, use large channel locks to gently remove. Too much pressure and you may crack the impeller. A strap wrench is a useful tool for impeller removal, but the key is to secure the shaft.

A few pumps have a reverse threaded impeller screw (Challenger, Hydro). After pulling the pump, look into the center of the impeller. If you see a screw head, use a good fit screwdriver to remove the reverse threaded screw, clockwise. These are often made of brass, which has softened over time, so to avoid damaging the screw, use a screwdriver that fits the screw head properly.




6. Remove the Seal Plate: You will find 4 bolts to remove the seal plate from the motor. After the bolts are removed you may need to pry or hammer slightly to remove the plate.Remove the seal half or "donut" portion of the shaft seal in the center of the plate.

7. Install the Seal Plate: Onto the new motor, bolt the seal plate with the "donut" half of the shaft seal firmly pressed into the seal plate, in the same orientation as the old seal half removed from the seal plate. Be careful not to touch the ceramic face with greasy hands or allow the seal half to become scratched. If it's too tight to push in by hand, use a small piece of 1" pipe, with a shim of light cardboard to press fit the seal into place. A rubber lubricant can be used, or you can use a little bit of saliva to lubricate.

8. Install the Impeller: Much easier this time. Just thread it on. But first you will need to replace the half of the seal which has the spring. Make sure it goes on correctly - one side has a soft rubber and one side has a harder plastic. The plastic side faces the ceramic donut half of the seal and the rubber side faces front, toward the impeller. If your impeller has an impeller screw - replace after spinning the impeller on all the way onto the shaft. If your pump uses what is called a "keyed shaft" motor, then you will have a brass stub shaft that will fit over the keyed shaft. After threading the impeller onto the stub shaft, you will align the impeller very close to the seal plate, and then tighten up the set screws which hold the stub shaft onto the keyed shaft.

Before re-inserting the motor into the pump, make sure to replace the diffuser over the impeller (I always forget this step!). Be sure the diffuser gasket or o-ring is in place before sliding motor back into the pump housing.

9. Replace the Motor into the Housing: Clamp it together making sure the seal plate is making good contact all the way around. Lubricating the seal plate o-ring will help ensure a good fit. Lubrication can also help to hold the o-ring in its groove as you position the two pump halves together. On some Sta-Rite and Pac-Fab pumps this can be very helpful. Get your bolts tightened up snug, but no need to put 100lbs of torque on them. Same thing with the clamp band. Tight, but not overly tight. Tapping a clamp band around it's edges as you tighten can make for a better fit. 

10. Replace the Wiring: Your new motor will come wired for 230V. This is to prevent the damage of hooking up 230V into a motor that is wired for 115V. If you do have 115V powering your pump (one that plugs in to an outlet, or is connected to a 115V timeclock) then you will follow the wiring diagram on the motor label. This label will guide you to reversing the voltage, or changing the voltage from 230V to 115V. Larger motors will be reversible (115 or 230) or they will be 230V only.

If you are 230V - then simply run the wires through the conduit connector that you screwed onto the new motor, and connect the ground wire to the green screw. Then put your two hot wires onto the two terminals. It doesn't matter which wire goes to which terminal. make sure that your wires are not touching each other, or the sides of the motor. Strip new wire ends if needed, inspecting the wires for bare spots or deteriorated casings. Tighten down the wire connections firmly, and replace the motor end cap, being careful not to pinch wires.



Fill pump with water: All the way to the top. Inspect the pump for drips or leaks. If there are none, pat yourself on the back, and continue to open any closed valves and test out the pump. If water is leaking somewhere, stop and fix at this time.







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