Pool pump not priming, leaking or making noise?

Problem 1: the pump will not prime

A pump that runs but moves no water is nearly always drawing air, or was never given enough water to start with. Work through these in order — the first four fix the large majority of cases:

• Water level too low. If the pool level drops below the middle of the skimmer mouth, the skimmer gulps air. Top the pool up first and retry.
• Blocked baskets. Check the skimmer basket and the pump strainer basket. A basket packed with leaves starves the pump.
• The lid O-ring. The single most common cause. If it is dry, cracked, flattened or has grit on it, the pump sucks air past it. Clean it, apply a suitable silicone-based waterproof grease, and hand-tighten the lid — never overtighten.
• Not enough water in the strainer. If the pump sits above the water line, remove the lid and fill the basket with water before starting.
• Valves. Confirm every suction and return valve is fully open, and that a multiport valve is not left between positions.
• A suction-side leak. If the pump primes then loses prime, or you see a steady stream of small bubbles in the returns, air is entering somewhere on the suction pipework — often a cracked fitting or a perished union O-ring.

If the pump still will not hold prime after all of that, the usual culprits are a failed shaft seal letting air in, a cracked pump housing, or a suction line problem underground. At that point it is a technician job.

Problem 2: the pump is leaking

Where it leaks tells you almost everything:

A mechanical seal leak matters more than it looks. Once water reaches the bearings and motor, failure follows quickly, so a small drip under an older pump is a warning rather than an inconvenience.

Problem 3: the pump is noisy

Noise is a diagnosis in itself:

• Rattling or gravelly — debris in the impeller or a blocked basket. Clear the baskets first; a stone or twig in the impeller is common.
• Screeching, whining or grinding — worn motor bearings. These are a wear item, and the noise generally only gets worse.
• Loud sucking or gurgling, with bubbles — air on the suction side. Treat it as a priming problem (above), not a motor problem.
• Humming but not starting — often a failed capacitor or a seized motor. Turn it off and call a technician; leaving it humming can damage the motor further.
• Just plain loud, always — nothing is broken. Older single-speed pumps run at one high speed and are simply noisy. A variable-speed pump at filtration speed is dramatically quieter, which is why noise complaints are one of the most common reasons people upgrade.

Pump on its last legs? In NSW, see what a new 6 star pump costs after the rebate before you pay for a repair. Your installed price comes back by text and email within a couple of minutes. The installed price and NSW rebate apply to NSW homes.

Pool pump hums but won't start

A hum or buzz with no spin usually means the capacitor no longer has enough charge to start the motor, or the motor has seized. Switch it off rather than leaving it humming, since that can damage the motor further.

The capacitor is the cheaper fix, typically $80 to $200 fitted, against $300 to $800 for a new motor. Both are licensed electrical work, so there are no DIY steps here: have a licensed electrician or pool technician diagnose it. Our guide to pool pump repair costs lists the price of each fault.

Pool pump trips the safety switch

A safety switch turns the power off as soon as it detects an electrical fault. If it trips when the pump starts, leave the pump off and don't keep resetting the switch. With pool pumps, the usual causes are water getting into the motor, either past a failed shaft seal or from rain, and damaged wiring.

A safety switch that keeps tripping needs a licensed electrician. Water in the motor can wreck it, so on an older pump get the repair quote in writing and compare it with a new pump before you agree.

Pool pump not working at all

No hum, no display, nothing. Work through the simple checks first, without opening the pump or touching any wiring:

• Power. Check the pump is switched on at the power point or isolator, and that the safety switch or circuit breaker hasn't tripped. If the safety switch has tripped, see the section above.
• Timer. A mechanical timer can lose its time after a power outage, or have a loose tripper, so the pump is never told to start. See the timer section below.
• Display. On a variable speed pump, a blank display or a fault light needs a technician. Some workshops repair the controller boards.
• Motor. If the power and timer are fine and the pump still does nothing, the motor or its wiring has probably failed. That is licensed electrical work.

Pool pump timer not working

If the pump starts and runs normally but not at the times it should, the timer is the likely problem. On a mechanical timer the usual causes are a clock that needs resetting after a power outage, a clock wheel out of position, loose or damaged trippers, or a worn-out timer motor. Resetting the clock and trippers is ordinary owner maintenance. Replacing a timer wired into the switchboard or a control box is a job for a licensed electrician.

Variable speed pumps have a built-in programmable timer, with separate run periods and speeds through the day, so the schedule is set on the pump itself. For how many hours to set, see how long to run a pool pump.

How to tell if the pool pump motor has gone

These signs point to the motor rather than the plumbing. They are symptoms to note before you call a technician, not tests to run yourself:

• It hums or buzzes but won't spin, and a new capacitor hasn't fixed it.
• It trips the safety switch every time it starts.
• A screech, grind or rumble that keeps getting louder, which usually means worn bearings.
• Water around the motor, or coming out of the motor vents.
• It does nothing at all, even with the power and timer confirmed working.

Testing the windings or the capacitor is licensed electrical work, so leave the testing to a licensed electrician or pool technician. If the motor has gone, a new one costs $300 to $800 fitted. On a pump over about 8 years old, a whole new pump usually makes more sense.

Get my price

Repair or replace? The honest arithmetic

Cheap parts are always worth fixing. The decision only gets hard when the motor end is involved:

Indicative only — actual quotes vary by pump, brand, parts availability and location.

For published repair prices on each fault, including capacitors, shaft seals, bearings, impellers and motors, see pool pump repair costs by fault.

The reason the maths tips toward replacement earlier than people expect is the running cost. An old 1.5HP single-speed pump running seven hours a day costs roughly $900 a year in electricity at a typical Sydney tariff. A 6 star variable-speed pump usually costs about $140 to $240 a year, depending on pool size. So a $500 repair on a fifteen-year-old pump buys you a working pump that still costs $900 a year to run — while a replacement removes both problems at once. You can check the figures for your own pool with the pool pump running cost calculator.

Five checks that prevent most faults

• Empty the skimmer and pump baskets weekly — blocked baskets cause more pump damage than anything else.
• Grease the lid O-ring a few times a year, and replace it when it stops looking round and supple.
• Keep the water level above the middle of the skimmer mouth.
• Leave clear air space behind the motor — overheating from a blocked vent is a common and avoidable failure.
• Never store pool chemicals next to the pump; the fumes corrode metal parts and most warranties exclude the damage.

Simple maintenance that adds years

• Keep the motor dry and give it room to breathe. Rain and poor airflow around the motor housing are common causes of motor burnout.
• Clear leaves and debris from the motor fan cover and vents.
• Never run the pump dry. It can quickly destroy the shaft seal, and running dry can void the warranty.
• Backwash a sand or glass filter, or clean a cartridge filter, when the pressure reading climbs. High filter pressure is one of the common causes of motor burnout.
• Sit the pump on a firm, level base. A rattle often comes from the surface it sits on, and a rubber mat can stop it.
• Act on a small drip under the pump straight away. A shaft seal is a $100 to $300 job; a flooded motor is not.
• Have the equipment serviced once a year. In Sydney an annual equipment service without parts costs about $170 to $460.

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