How To Replace A Pool Pump Diffuser

Written by:  Danny Rhodehamel
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The location of the pool pump diffuser is shown in this cut-away of a pump. The pool pump diffuser surrounds the pump impeller. It's purpose is to control the flow of water to and from the impeller. For a more complete discussion of the function of the diffuser click How A Pool Pump Works. Sometimes hard debris will get into the pump and will crack the diffuser. In other cases the threads that hold the impeller to the motor shaft become worn causing the impeller to wobble and rub against the diffuser. This guide explains how to replace a bad pool pump diffuser in a Hayward Pump, however, the pool pump's parts and it's operation are common to most pool pumps.

Tips & Warnings

Things You'll Need

Step by Step

Step 1
pool pump diffuser

The first step in preparing to remove your pool pump's diffuser is to turn off all power to the motor. For maximum safety turn off the power at the circuit breaker to the motor - usually located next to the timer box.

Step 2

Next you will have to relieve the pressure that builds up in the pool pump during operation. To relieve pressure turn the relief valve on top of the filter counter clockwise. Water will spray out initally as you see the pressure on the pressure gauge go to 0 psi.

Step 3
hayward pool pump bolts

To extract the motor pump assembly from the pump housing, first remove the four 9/16" bolts that bind the motor pump assembly to the housing. Keep track of the washers. Note: Some Hayward pool pumps have six bolts.

Step 4

Pull the assembly apart from the housing.

Step 5
pool pump diffuser

After the assembly is out, you should see the pool pump diffuser and diffuser gasket on the end of the assembly. If you do not see the diffuser or its gasket, check inside the housing.

Step 6
pool pump diffuser

If the pool pump diffuser came out with the assembly, pull the diffuser off the assembly. It should snap off easily.

Step 7

Place the pool pump diffuser gasket is on the collar of the new diffuser properly. Put a thin coat of lubrication on the gasket.

Step 8
pool pump diffuser

Snap on the new pool pump diffuser - no screws are required. Ensure that the part of the diffuser labeled "TOP" is aligned with the "TOP" labeled on the seal plate.

Step 9

Slip the motor assembly back into the housing.

Step 10
pool pump bolts

Replace the four bolts evenly. If bolts were numbered 1 though 4, replace bolts in this sequence - 1, 3, 2, 4 - to ensure that the motor is set properly inside the housing. Loosely tighten bolts in this sequence, then go back and tighten them down again in this sequence. If pump has 6 bolts, replace bolts in this sequence - 1, 3, 5, 2, 4, 6.

Step 11
pool pump diffuser

Prime pool pump by removing strainer lid and filling strainer with water. Replace lid.

Step 12

Reset circuit breakers to start pool pump.

Step 13
pool pump diffuser

Close the relief valve on top of the filter. Wait until after the air is purged and water starts to spray out of the valve.

Comments (1 to 3 of 3)

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User: Inyopools

screech - Thanks for your comment. Glad we could help and we appreciate your business.

User: screech

Because of your great directions and that you are smart enough to put them there as a sales enhancer, I will purchase my parts from you.

User: Bobcat

Great information on replacing your pool pump diffuser

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Please Note:

Inyo Pool Products is not responsible for any injury or damaged equipment
while using our guides. Using our guides is doing so at your own risk.
These guides are suggested use of your pool or spa equipment and may vary
depending on which product you are using.