Introduction: Restoring Seized Pool Water Pump (with Pictures)
As I was starting up my pool this season, I noticed that the main filter- and circulation pump was stuttering at startup, and was making a rather discomforting, loud grinding noise while running.
After checking that the capacitor was fine, I figured it was bad bearings, due to moisture getting in the motor, so I decided to rip it down and rebuild it.
Now, while this project does not require any fancy tools, some supplies are needed.
Pictured, from top-left.
- Small magnetic bowl, for holding nuts and bolts. *Optional
- New bearings. The exact model will depend on your specific motor, I tore mine down and then went to my supplier to get new ones. Try to get rubber-sealed ones as opposed to the cheaper, metal-sealed ones. (the metal sealed ones are cheaper, and has less resistance, but are in my opinion not the correct choice here)
- Some fine-grit sandpaper/abrasive to clean any rust of the shaft, rotor or stator.
- Penetrating oil / water-displacement spray.
- Strap pipe wrench. (used to remove the pump impeller from the threaded shaft) *Optional, you may be able to get a grip on the impeller by other means. This simplifies it though.
- Dual-headed plastic and rubber hammer. *Optional, you may use any other soft hammer, or rubber mallet.
- Small-ish flat-head screwdriver. (to pry things with, if stuck)
- PH2 - head screwdriver.
- Socket-wrench and matching sockets for your pumps nuts and bolts.
- Small socket or pipe used to drive the new bearings down the shaft. You must make sure this ONLY contacts the bearings INNER ring, otherwise you will damage the bearing.
Step 1: Remove the Outer Pump Housing
Using the PH2-screwdriver, remove all the bolts (six on my pump) holding the outer pump housing to the motor, undoing them in a crosswise pattern.
Step 2: Remove the Pump Housing O-ring and Impeller Shroud
Remove them both, taking care not to damage the O-ring (or you will need to get a replacement).
The shroud pulls straight of, being held in place by the outer pump housing in this model.
Step 3: Remove the Cooling Fan Cover and Fan
- Undo the four small bolts holding the cover in place in a crosswise pattern, and remove the cover.
- Undo any bolts holding the cooling fan in place (mine had none) and pull it of the shaft.
Step 4: Remove the Impeller
- Use a wrench or pliers on the rear end of the shaft to hold the shaft still.
- Using the strap pipe wrench, unscrew the impeller from the threaded shaft.
Take utmost care not to touch the surface of the shaft seal, a single fingerprint can cause leaks.
Step 5: Remove the Inner Pump Housing
Using the socket wrench, undo the four long bolts holding the inner pump housing to the motor.
They are hidden under the fan cover here, I forgot to remove it before taking the picture... Silly me.
Step 6: Remove the Motors Rear End Cover, and the Rear Bearing
- Using the dual head plastic and rubber hammer, gently tap the motors rear end cover, while pulling it forward of the motor housing. (use the flat-head screwdriver to pry it off, if needed). Take care to keep track of any seals, gaskets or spacers here.
Now we can choose between letting the shaft and rotor stay in the motor while pulling the bearing of, or removing the whole rotor assembly first.
I choose to leave it in.
- Give the bearing a few squirts of penetrating oil, and wait a few minutes to let it do it's magic.
- Using the bearing puller, pull the rear bearing of the shaft.
Be careful not to damage the electrical windings, or the insulating lacquer.
Step 7: Remove the Rotor, Front End Cover and Front Bearing
- Using the dual headed hammer again, gently tap the front end cover, pulling it and the rotor out of the stator.
- While holding the rotor still, gently tap the cover with the dual headed hammer while pulling it of the outer ring of the bearing. Some penetrating oil here may help.
(Again, keep track of any spacers or gaskets.)
- Give the bearing a few squirts of penetrating oil and let it sit for a few minutes.
- Using the bearing puller, remove the bearing just like the rear end bearing.
Step 8: Clean Everything, Remove Rust Etc
Now at this point, the motor is fully mechanically disassembled, and we are truly in the middle of this project. This is a good time to grab some coffee. :-)
Get some tissues or towels and wipe everything clean of dust, penetration oil, dirt etc.
For the rotor and stator:
- Using the fine-grit abrasive, gently remove the rust and corrosion from the rotor and stator.
- When working on the stator, I found that wrapping the abrasive around a screwdriver and using that to grind away the rust worked very well. Take good care not to damage the electrical windings with the abrasive here, you may want to cover them up while working on this stage.
Make sure not to leave any particles inside the stator or the electrical windings.
Step 9: Replace the Bearings
To make things easier to get the new bearings in place, I like to put the shaft the freezer and the bearings in the oven before mounting them, using the fact that metal expands and contracts with differing temperatures to get some leeway in the assembly stage.
- Put the rotor and shaft in the freezer, and the new bearings in the oven, set for about 80 degrees centigrade.
Let them stew for a while to get a good temperature difference between the two parts.
- Push the new bearings into place on the shaft (take care now, they are hot! Use gloves or wrap them in some cloth while handling them!). Hopefully the temperature difference will allow them to slide smoothly on, if not, drive them into place using a pipe or socket that only makes contact with the bearings INNER ring!
Step 10: The Final Stage, Doing It All in Reverse
Now, with the new bearings in place, and the rotor and stator free of any rust buildup, the last stage is just doing it all in reverse. :-)
Tighten all bolts in a crosswise pattern.
The main steps:
- Put the motor front cover back on the rotor, and the entire assembly back into the stator.
- Replace the motor rear end cover.
- Using the four long bolts, mount the inner pump housing to the motor.
- Mount the cooling fan and the cooling fan cover.
- Put the impeller back on the shaft, using the strap pipe wrench (or similar tool) to tighten it.
- Add the impeller shroud and the O-ring to the inner pump housing.
- Replace the outer pump housing (make sure the O-ring is seated correctly), this is easiest by just getting the outer housing partway on and using the bolts to "pull it" tight against the inner housing.
That's all folks. After this, it should be running smoothly again.