How to Read an AO Smith Pool Motor Label

WRITTEN BY:  Matthew S.

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When the time comes to replace your pool pump motor the jumble of numbers and ratings on a motor can be overwhelming. This "How to" will guide you through which information is useful in your replacement pump motor search. We also provide tips on essential parts that should be replaced when installing a new pump motor.

Step by Step


Step 1

Tools you may need: 1. A cloth and cleaning solution, this is needed to remove any dirt or grime causing your pump motor label to be unreadable 2. A Shaft Seal or GOKIT when replacing your motor. Working seals and gaskets are vital to the health of your pool pump. A malfunctioning shaft seal will cause water from the pump to leak into your electrical motor causing it to fail prematurely. A GOKIT includes the complete set of your pumps gasket's and O-rings, including the shaft seal.

Step 2

In general there are two main labels on a pool pump; the pump label and pump motor label. Both can be used to determine the correct motor replacement but first we will focus on the motor label as it is the quickest and easiest to search. If your motor label is unreadable, later in the guide we will show you how to backtrack information off your pump to find the correct replacement. Quick Tip: The manufacturer of the pump motor and the pump itself are different companies even if the pump is brand new from the factory. For example, you have purchased a Hayward Super Pump, the wet end of pump where the water is housed is made by Hayward. The motor attached to that pump wet end was likely made by A.O. Smith, Century or Marathon.

Step 3

An A.O. Smith pump motor label has a lot of different numbers and ratings that can have an appearance of alphabet soup at first glance. Let's narrow down the scope to just the information we will need to search for a new pool pump motor replacement. The list is as follows: Motor Model Number, Horsepower (HP), Service Factor (SF) and Frame (FR)

Step 4

When reading an A.O. Smith pump motor label the most pertinent information to aid you in finding a replacement is the "Motor Model Number." With this information alone you could find the exact match. As shown in the picture, an A.O. Smith motor may have two model number formats listed, either one can be used in INYO's pool pump motor search engine.

Step 5

The first format is one that follows the line of "UST1102", "ST1102" or "SN1102". The set of letters in the beginning denote the service factor rating of the pump. The "UST-" stands for an uprated motor and "ST-" means it is a full rated. The last four digits show its HP: "-1102" = 1 HP, "-1152" = 1.5 HP, "-1202" = 2 HP and so on. Type complete number (ex. UST1102) into INYO's product search at the upper right-hand portion of our site to find pool pump motor match

Step 6

The second format of pump model numbers contains a prefix that is most commonly "C48", "C56", "K48" or "K56". This prefix is followed by four to nine letters and numbers which identify the specific motor. Type this entire number into INYO's product search to find the correct pump motor match. An example of this pump model number format: C48L2N134C1

Step 7

If the Motor's model number is unavailable then we will have to use a combination of the pump label information and other available info on the motor label. The information needed off the motor label is the Horsepower (HP), Service Factor (SF) and Frame (FR).

Step 8

In most cases the Pump's manufacture label is located near the outlet port, location may vary depending upon the maker.

Step 9

On the pool pump label there should be two numbers listed, the serial and model. The pump model number can be entered into our product search engine; the result should provide the make, model and horsepower. Copy down this information and enter our pump motors section by selecting it in our “Shop by Category” sidebar.

Step 10

In the Pump Motors section you will be asked for the manufacturer then the model. Your specific model may have two categories that list by your pump motor's service factor (SF). The motor's SF is listed on the label, this number will be in the range of 1.00 - 1.95. A SF of 1.00 to 1.27 is listed as an Up rated, anything over is Full rated. Please be sure you match the Service Factor of your pump as failure to do so will cause incompatibility between your current pump and new replacement motor.

Step 11

After checking all the previous information and have found a possible correct replacement, your last piece of info to check will be the Frame (FR). Most motors have a frame of "48Y", "56Y", "48J" or "56J". If your prospective replacement matches HP, SF, and FR then you have successfully found your motor replacement.


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Anonymous  Posted: 09/02/2016 11:34 AM 

K48K2N104CA - The number you gave me is the motor identification. If you are looking for the motor shaft seal, I would have to know what pump you have since half of the seal goes into the pump's seal plate. Need pump manufacturer and model name like Hayward Super II pump.

Anonymous  Posted: 09/01/2016 14:11 PM 

I have a K48K2N104CA Hayworth and need to replace the pump seal.
Can you help identify the seal number?

Inyopools  Posted: 06/06/2016 10:18 AM  Inyo Product Specialist

Gotha - That's the right size pump for your size pool. And you are right, that's too many motor failures for your pool. I would look at your pool system conditions. Does your motor run very hot? Make sure there is no debris around the bottom vents of the motor. One customer said he was able to reduce the motor heat and amperage use by placing the pump on a cinder block. Another thing to look at is voltage into your system. If the supply voltage is more than 10% higher than 220, your motors will fail quicker. Check your supply voltage at different points of the day. Lastly, you might consider a VS pump. They are designed to last longer and will reduce your operating cost considerably.

Gotha  Posted: 06/03/2016 21:15 PM 

Currently have AO Smith UST1152 C48L2N134C1 1.5HP 230V. Pool approx. 13k-15k gallons. I have replaced 3 motors in 6 years, now going on #4 (all have been same motors). new Seals and lube added each time. This doesn't seem normal. Pool in summer months approx. 6 hours/Winter 4 hours; auto timer on daylight hours. Piping is 2". Solar Heat. Spray heads on low on weekends. Pool level is consistent. Screened in, very little debris, and cleaned minimum of twice a month. Normal amount of chemicals used. What is a better alternative or is this the best choice?

Inyopools  Posted: 05/31/2016 13:02 PM  Inyo Product Specialist

Mark - I would suggest looking at a Hayward Super 2 Energy Efficient Pump 1 HP Single Speed. It runs quieter, is about 20% more efficient (uses fewer amps) and is more powerful than your current pump. Actual or Total HP (THP) is measured by multiplying the listed HP (1HP) by its Surface Factor (1.5) generating a THP of 1.5 HP.

Mark  Posted: 05/29/2016 12:06 PM 

I have a AO Smith 1081 Design ST102 1hp motor with a 56J frame that I believe has a bearing going bad. It drives Hayward model SP2607X10 pump. I want to replace it with something quite, more efficient and a little more powerful. What would you suggest?

Inyopools  Posted: 05/09/2016 11:15 AM  Inyo Product Specialist

Motor identification - Sounds like you have identified the motor model correctly as a Hayward Super II. To find the size, take the motor out and look for the part number on the impeller. Then go to this Hayward Super II Parts link to see what motor size matches your impeller. Give us a call at 877-372-6038 if you need further assistance.

Anonymous  Posted: 05/07/2016 13:53 PM 

Trying to decipher motor model. All that's left on the label is A11J130304 and is located on the bottom just above a UPC bar code. The only other thing I see is a feed wire diagram and the fact that it was assembled in Mexico. I think the housing is a Hayward Super II, as the lid has part #SP3100D.

Inyopools  Posted: 04/19/2016 8:41 AM  Inyo Product Specialist

Cliff - I would recommend the 1.65 HP Variable Speed Pool Pump Motor Square Flange for a replacement motor. It will adapt easily to your current pump. The VS motor costs more initially but it is a newer more durable design and you will recoup your initial cost in up to 80% operating saving is just over a year.

Cliff  Posted: 04/18/2016 22:55 PM 

Thank you. I do have another question, though. Would I be better off with a 2 speed or variable speed pump motor, and if so, is there one - from any manufacturer - that would fit just like the B2661?

Inyopools  Posted: 04/18/2016 14:19 PM  Inyo Product Specialist

Cliff - The Energy Efficient replacement motor for your current 7-177215-04 motor is B2661. It will save you about 15% in energy costs. Their Total HP (HP x SF) are the same. THP on 7-177215-04 is 1 HP x 1.25 SF or 1.25. THP on B2661 is .75 HP x 1.67 SF or 1.25.

Cliff  Posted: 04/16/2016 20:12 PM 

I have a Mustang 56 frame in-ground pool pump by Waterway P/N MUSTS-110 with an A.O. Smith Centurion switchless motor. The motor's P/N is 7-177215-04, Type CX, P56Y Frame, Ph 1, 1.0 HP, 3450 RPM. It sounds like the motor bearing is failing and I am interested in replacing the motor. Is there a more efficient replacement pump with the same bolt pattern, shaft, etc.?

Inyopools  Posted: 02/24/2016 18:13 PM  Inyo Product Specialist

Date of Manufacturer - Yes. The month and year that your pump's motor was manufactured is incorporated in the motor's serial number. If you have an A.S Smith (now Century) motor, give them a call at 937-667-2431 and they can help you decipher it.

Anonymous  Posted: 02/23/2016 18:31 PM 

Is there a way to find out when the motor was built/made/manufactured?

Inyopools  Posted: 07/15/2015 23:40 PM  Inyo Product Specialist

MR Hughes - We need to know the model of your Sta Rite pump in order to give you the correct Shaft Seal. The motor model # is not used to identify the shaft seal.

MR Hughes  Posted: 07/14/2015 21:11 PM 

I am looking for the correct Shaft Seal for my Sta-Rite system if I am upgrading to a V-Green 165 on my System:3 DE Sta-Rite filter. The current motor model # is K48L2PA101A1

Inyopools  Posted: 06/22/2015 15:57 PM  Inyo Product Specialist

Mr vek - Your model number does not come up in our system. If you could give us your pumps manf and model name and the Service Factor [SF] specified for your 2 HP motor, we might be able to find your capacitor. See our guide on "How To Select the Right Capacitor For Your Pool Pump Motor" for more information.

Mr vek  Posted: 06/21/2015 12:37 PM 

I'm looking for a capacitor for AO Smith 2HP motor,
Ser 026093M, Model SP1520Z1EFTC. My motor was working,
but now shuts off the circuit braker after start up.
In viewing utube it indicates the capacitor is the
problem. What is your opinion?

Mr Vek 6-21-15

Inyopools  Posted: 06/02/2015 11:54 AM  Inyo Product Specialist

capacitor - Here is our link to your capacitor you requested - 124-148MFD. Please verify that your capacitor is specified for 125 VAC. Also see our guide on "How To Select the Right Capacitor For Your Pool Pump Motor" for more information.

Anonymous  Posted: 06/01/2015 19:16 PM 

I'm looking for a capacitor for a 1/2 horsepower A O Smith with the serial number of C45A93AO6 Met39 ABN also has a Goulds # J04853l

Anonymous  Posted: 06/01/2015 18:56 PM 

I'm looking for a capacitor for a 1/2 horsepower motor #124-148MFD

Inyopools  Posted: 05/30/2015 15:46 PM  Inyo Product Specialist

replacement gasket - The number you provided identifies the motor in the pump. We would have to know the make and model of the pump like Hayward Super pump to identify its gaskets.

Anonymous  Posted: 05/29/2015 11:38 AM 

i am looking to find a replacement gasket kit for a A.O. Smith Century Pump on Haywark unit SP1520Z1EFTC 2HP LEAKING THRU HOUSUNG . can anyone help me

Inyopools  Posted: 05/20/2015 8:01 AM  Inyo Product Specialist

mike - Here is our link to that motor - B855. When you replace the motor, you will also have to replace the shaft seal. The seal for your motor depends on the brand of pump. See the bottom of this linked page for probable options.

mike  Posted: 05/19/2015 10:26 AM 

Looking to replace an A O Smith Model B855

Inyopools  Posted: 05/12/2015 15:05 PM  Inyo Product Specialist

UST1202 Replacement – This is the link to your replacement UST1202 motor. For the GOKIT, we need to know the pump manufacturer and model. It is probably a Hayward pump, but we don’t know the model – Max Flo [GOKIT1], Super [GOKIT3], Super II [GOKIT2] or Northstar [GOKIT56]. If it’s not one of these models, see “Hayward GOKITs”.

Anonymous  Posted: 05/12/2015 13:31 PM 

Hi - I need to replace an AO Smith UST1202, 2HP, 1.0 SF, 56J motor. Can you recommend replacement motor and specific GOKIT that goes with that motor?

Inyopools  Posted: 05/11/2015 16:30 PM  Inyo Product Specialist

rick - I don't see your model # in our system. However, to match your pump motor, you need to compare its HP, Service Factor (SF) and Frame (FR). If these match, your motor's amp will match.

rick  Posted: 05/11/2015 14:14 PM 

I'm looking to replace AO Smith spa pump model #001438SE. I was told matching the Amps is important. The label says A 9.0. does that mean I have a 9 amp motor?

Inyopools  Posted: 05/07/2015 17:35 PM  Inyo Product Specialist

pump replacement - For your above ground pool we would recommend replacing your Astral Sena 1800 1.5HP 115V 2 speed pump with a Hayward Power-Flo LX 1 1/2 HP, 115V, 1 Spd. Pump.

Anonymous  Posted: 05/06/2015 20:12 PM 

would like to replace this SEN1815D with a hayward dont have to be a 2 speed what is suggestion

Inyopools  Posted: 08/12/2014 13:31 PM  Inyo Product Specialist

steve - Some motors show the age of the motor in the serial number on the motor label. The first digit is the plant, the second the month and the next two the year. For example, if your motor's serial # starts with 8A02. it was made in plant 8 in January of 2002. If you don't see similar information in your motor's label, call the manufacturer of the pump and give him the motor or pump serial number.

steve  Posted: 08/12/2014 8:47 AM 

Is there anyway to tell how old a pump is I ,m thinking of buying a previously owned 1 1/2 H.P. super pump.?

Inyopools  Posted: 04/25/2014 10:26 AM  Inyo Product Specialist

ac - Motor are designated as round frames or square frames. It relates to the style of mounting plate on the pump housing to which the motor is mounted. See our guide on "How To Replace the Motor on Your Pool Pump" for an example.

ac  Posted: 04/23/2014 18:19 PM 

What does frame mean/indicate???does it signify the face to which pump or device will attach??

Inyopools2  Posted: 03/09/2014 9:12 AM 

Hi Shirl - you would require the B2982 motor located here

shirl  Posted: 03/08/2014 15:37 PM 

my label says Century two speed A.O. Smith Cat--- Serial CA07-25
Part 7-193508-01

Inyopools  Posted: 11/09/2013 10:59 AM  Inyo Product Specialist

Donald - You may have an older label or occasionally we will see an off standard label. However, if you type the part number, 7-177803-02, into our general search field, our site will bring up you pump description as a BN50 1 1/2 HP 2 Speed 115V Thru Bolt Motor.

Donald  Posted: 11/08/2013 10:50 AM 

unfortunately my motor label doesn't conform to your description. There's no "model number" listed, hp simply says ---, same for SF ---. It's an A.O. Smith label: there's a reference to a 1081/1563 pump duty, a Cat BN50 and a part number: 7-177803-02. Says HP 1. There's RMP, etc. but none of the label conforms to your description

Inyopools  Posted: 10/30/2013 9:31 AM  Inyo Product Specialist

Mike - Here's the link for A.O.Smith motor switches. Try A.O.Smith direct for applicable wiring diagrams.