Symptoms
- Loud grinding, screeching, or rattling from the pump motor
- Humming sound but the motor doesn't spin
- Noise changes pitch depending on valve settings
Likely causes
- CommonWorn motor bearingsBearings wear out over years of continuous running and cause a grinding or screeching sound.
- CommonDebris caught in the impellerSmall debris that passes the strainer basket can rattle inside the pump housing.
- PossibleCavitation from restricted water flowA clogged filter, closed valve, or clogged skimmer can starve the pump of water, causing a rattling or marble-like sound.
- PossiblePump running dryA pump with no water to pump can overheat and make a loud humming or grinding noise quickly.
What to do
- Turn off the pump immediately if it's making a severe grinding noise or appears to be running dry.
- Check the water level and skimmer basket, filter, and pump strainer basket for clogs restricting flow.
- Open the pump housing (after turning off power) and inspect the impeller area for trapped debris.
- Listen closely to identify if the noise is from the motor itself (likely bearings) versus the wet end (likely debris or cavitation).
- For a humming motor that won't spin, check if the shaft is seized or the capacitor has failed, both of which need parts replacement.
- Replace worn bearings or the motor if that's confirmed as the source, since bearings alone are hard to service on sealed pump motors.
Tools and parts
- Screwdriver
- Flashlight
Pool pump motorSearch: “pool pump motor replacement”
Pool pump capacitorSearch: “pool pump motor capacitor”
When to call a pro
A pool technician can diagnose and replace a failed pump motor, which is often more practical than attempting to service bearings yourself.
Safety
Use caution
Always shut off power to the pump at the breaker before opening the housing or touching the motor.