By Century Motors



Part # B625

Warranty 1 Year

Alternate Part #'s 0-173840-23, 10-173840-23, 142777, 173289, 173840, 176830, 2-173840-23, 5KC46KN2408X, 7-173840-13, 7-173840-23, 7-173840-32, 7-173840-53, 7-173848-23, 8-142777-21, 8-173840-20, 8-173840-23, C1502, EB625, PL1072, AOSB625, MGT-60-5109

Product Description

Uprated 3/4 HP motor; 3450 rpm, 208-230/115; 8.5-7.8/15.6 full load amps; 1.5 service factor; 56CZ frame

Most commonly used on Polaris Booster Pumps

Motor Dimensions Motor Dimensions
Motor Image Motor Image

Product Specifications

0.75 HP
115/230 V
12.8/6.4 amp
Service Factor:
Total HP:
1.13 HP
Century (A.O. Smith)
3450 RPM

?     Asked on 1/11/2012by Guest

What is Service Factor?

A  Answered on 1/11/2012 by InyoPools Product Specialist Patrick P.

Service Factor(SF) is a multiplier that when multiplied by the horsepower of the motor indicates the total permissible horsepower loading that may be carried when the motor is operating at rated voltage and frequency. The most important thing to remember when replacing a motor is that the replacement motor's horsepower times its service factor must be equal to or greater than the original motor's horsepower times its service factor. The Service Factor rating can be found on the motor label. See Step 4 of our How to Read a Pool Motor Label guide.

?     Asked on 1/12/2012by Guest

Why do I need to purchase a new shaft seal?

A  Answered on 1/12/2012 by InyoPools Product Specialist Patrick P.

We strongly recommend replacing the shaft seal. The purpose of a shaft seal is to prevent water from running down the shaft of the motor and into the motor housing. Water will damage the bearings and cause the motor to fail. A new shaft seal should be installed whenever a motor is replaced. The motor manufacturer can deny the warranty if the motor fails to due to water damage from a faulty shaft seal. To find your shaft seal you will need to visit our Pool Pump Parts Page or the Spa Pump Parts Page and select your make and model.

?     Asked on 1/12/2012by Guest

Why should I purchase a Tune Up Kit?

A  Answered on 1/12/2012 by InyoPools Product Specialist Patrick P.

A Tune Up Kit includes all of the essential replacement seals and gaskets for the pump. The seals and gaskets should be replaced when installing a new motor on your pump. New seals will prevent the pump from leaking water or losing the prime. A Tune Up Kit will protect your motor and ensure that the pump is working efficiently.

?     Asked on 6/16/2015by Nate

I would like to order this pump. Which tune up kit do I need and impeller (if needed) go with it? Thanks, Nate

A  Answered on 6/16/2015 by InyoPools Product Specialist Joe S.

Hello Nate, the impeller needed is 3262-03 and seal 

?     Asked on 7/13/2015by William Petersen

I have a polaris pump ao smith part o-173840-23. It recentlt started a high pitch scream. Bearings ?? Something that can be easily replaced? thanks

A  Answered on 7/14/2015 by InyoPools Product Specialist Lennox H.

Hi William, You can replace the bearings of your Polaris booster pump motor. You will need (2) A.O. Smith 203 Bearing (6203RS). We have  How To Replace the Bearings in a Pool Pump Motor - Part IHow To Replace the Bearings in a Pool Pump Motor - Part II to assist you in replacing the bearings in your motor.


Est. Repair Time

Less than 1 hr

Tools Needed

Screwdriver, Nut Drivers, Wrench Set, Rags and mild cleaning chemicals

1     0

The existing motor housing and stators were corroded and the build up of rust was preventing the motor from turning freely.

Written on 9/18/2023 by Guest

I watched the video for this repair that inyo pools produced for guidance. I first cut power at the breaker. Then I disconnected the boost pump from the inlet and outlet hoses. I removed the electrical access plate from the back of the motor and disconnected the wiring, being mindful to take a photo prior to disconnecting. Then I carried the assembly over to a table and removed the impeller cover. I then removed the shaft cover and used a wrench to hold the shaft in place while I spun the impeller off by hand. I then removed the shaft seals and the aft impeller housing and was only left with the motor, which I discarded. Assembly was opposite of disassembly, but I purchased all new shaft and housing seals. Nothing worse than fixing something and then having to take it apart a month later because the old $5 seal failed. I hooked everything back up, turned the power on at the breaker and gave the system a test. The impeller sounded very loud, but I had the vacuum disconnected. Once I attached the vacuum to the wall outlet and the system got some back pressure load on it, the noise stopped and everything was working like new.

Were these instructions helpful? 


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