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Pool Pump Making Loud Humming Noise? Here’s Why (+ Easy Fix)

Humming pump motor noises can be worrisome. It’s never a good idea to let strange, new noises on your pool equipment go unchecked. These noises are often early indicators of motor problems.

Identifying the sound is essential for preserving your pool equipment and saving your wallet from having to get a new pump.

Your pool pump is making a loud humming noise because of one of these issues:

  1. Overheated pool pump
  2. Damaged motor shaft
  3. Air in the plumbing
  4. Faulty capacitor
  5. Equipment pad clogs

In this article, I’ll cover all of the reasons your pump is making a loud humming sound and what you can do about it. I’ll also talk about whether your not you need to replace the motor, impeller, or other parts.

1. Overheated Pool Pump

Does your pump keep tripping the breaker? If so, it might be overheating.

If the motor gets too hot, the pump will vibrate and hum. This sound is created by the non-stop friction, which makes the motor even hotter.

It’s important to turn off the pump as soon as you notice that the motor is too hot to touch with your hand.

How To Fix

The most important step is to identify the cause. This whole post is full of reasons your pump can overheat, so make sure you go through each of the sections to find out why yours is in bad shape.

You can fix the overheating problem by tightening loose wires, removing clogs, and getting rid of all air bubbles in the plumbing. You also might have to replace the capacitor, open the inlet and outlet valves, or get a new motor.

It’s best to start with the cheapest repair. Here are each of the aforementioned repairs in order of least expensive to most expensive:

  • Tighten the loose wires on the motor house, timer, and circuit breaker.
  • Open the air relief valve on the filter to remove excess air bubbles.
  • Open the inlet and outlet valves to ensure the water is free to flow to and from the pool.
  • Remove the clogs from the skimmer basket and pump basket, then clean the filter (you might need to hire a pro to blow the lines).
  • Replace the motor’s capacitor.
  • Get a new motor for the pump.

2. Damaged Motor Shaft

A bent or misaligned motor shaft will produce a low hum that gradually gets louder. This hum is caused by the shaft vibrating against the motor and the impeller.

Bent motor shafts are quite rare since they’re usually caused by cavitation, prolonged overheating, and manufacturer defects.

How To Fix

A damaged motor shaft calls for a repair from the manufacturer or a motor replacement, as most pool technicians aren’t qualified to replace the damaged motor shaft.

In fact, most companies suggest getting a new motor because the shaft requires you to send the whole motor back to the manufacturer and pay similar costs to a full motor replacement.

Here’s how you can replace the motor:

  1. Turn off the circuit breaker.
  2. Remove and label the wires on the back of the motor.
  3. Disconnect the retaining screws from the housing and the impeller to separate the motor.
  4. Connect the new like-for-like motor to the impeller and the pump housing, then attach the wires to the necessary wire nodes.
  5. Prime the pump and turn on the breaker.

3. Air in the Plumbing

The pump will overheat and hum if air bubbles get in the plumbing. This noise is produced by the hot motor bearings combined with the air filling the system.

Air in the lines will eventually damage the pool pump beyond repair. It can also cause harm to the heater, filter, and all other pieces of equipment on your swimming pool pad.

How To Fix

To remove the air from the lines, try these tips:

  • Open the air relief valve while the pump is running until the water flows out of it.
  • Always keep the water level in the pool above the highest inlet.
  • Make sure the suction-side plumbing (before the pump) isn’t too high above the pump’s inlet since it can cause an airlock.

4. Faulty Capacitor

The capacitor is a start-up battery for the pump’s motor. If the capacitor is damaged or old, the motor will hum.

The humming sound comes from the motor trying to start without the necessary assistance from the capacitor.

Most capacitors take a while to fail, which is why they hum until they stop working randomly.

How To Fix

The only way to fix a bad capacitor is to replace it. Installing a new capacitor requires discharging the old one, which can be hazardous if you’ve never done it before.

Here’s what you can do:

  1. Turn off the power.
  2. Disconnect the capacitor cover plate.
  3. Short the capacitor if necessary (check if there’s a charge with a multimeter).
  4. Remove the retaining screws and wires.
  5. Install the new like-for-like capacitor by attaching the aforementioned wires and retaining screws.
  6. Install the capacitor cover plate.

Inyo Pools shows how you can discharge and replace your pump motor’s capacitor below.

5. Equipment Pad Clogs

Clogs can occur anywhere in your pool system. Any clog will overwork the pump, making it hum, grind, and overheat.

Here’s a list of potential clog locations you should inspect:

  • All valves in the plumbing system
  • Skimmer baskets and pump baskets
  • Filter cartridges, sand, or DE fins
  • Jammed weir gate (also known as a skimmer gate)
  • Clogged plumbing, including pipes, unions, and couplings

How To Fix

Follow this process:

  1. Open the necessary valves to ensure the best water flow to and from the pool pump.
  2. Dump the debris from the skimmer basket and pump basket a few times each week.
  3. Clean your pool filter every time the PSI goes over 25 on the pressure gauge.
  4. Get a new weir gate if yours is jammed.
  5. Blow the lines with a pressurized hose from a pool technician, or use a drain auger to get rid of small clogs.

Pool Pump Noise Troubleshooting Resources

If your pump is making any other noises, my other pool pump noise troubleshooting articles may be able to help:

Author

  • Jonah Ryan

    Jonah has worked for several years in the swimming pool industry installing and repairing equipment, treating pools with chemicals, and fixing damaged liners. He also has plumbing and electrical experience with air conditioning, ceiling fans, boilers, and more. When he's not writing for Temperature Master, he's usually writing for his own websites, LawnCareLessons.com and DIYByHand.com.