The pump is the one piece of equipment that runs every day, and it is the one that tells you something is wrong before anything else does. Most of what it says is about air and water, not about the pump itself. Here is how to read the common symptoms.
The pump will not prime
Priming means the pump fills with water and starts moving it. If it runs and stays dry, or fills partway and loses it, check in this order:
- Water level. If the level is below the skimmer mouth, the pump draws air. Fill the pool.
- Pump basket. Open the lid, fill the basket housing with water from a hose, check the basket for debris and put the lid back on tight.
- Lid o-ring. Dry, cracked or dirty o-rings do not seal. Clean it, lubricate with a silicone-based pool lubricant, and seat it properly. This one item solves a large share of priming complaints.
- Valves. Confirm the suction valves are open and set to draw from the skimmer and main drain. A valve left in the wrong position after cleaning the filter is common.
- Skimmer. A full skimmer basket or a stuck weir starves the line.
Give the pump a few minutes to prime after any correction. If it still cannot pull water, there is an air leak on the suction side or a blockage in the line.
Bubbles in the basket or from the returns
Air in the system after priming means a suction-side leak. Suction lines are under vacuum, so they pull air in rather than pushing water out, which is why there is no wet spot to find. The usual sources: the pump lid o-ring, the drain plugs on the pump housing, the union fittings on either side of the pump, the stem of a suction-side valve, a cracked skimmer, or a cracked pipe underground. Work from the pump outward. A little water poured over each fitting while the pump runs will often show where the leak is; the bubbles change when the water seals it for a moment.
Low flow
Pump runs, primes, but the returns are weak and the filter pressure is odd. High filter pressure with weak returns means the filter is dirty. Low filter pressure with weak returns means the pump is not getting enough water: baskets, water level, a suction leak, or a clogged impeller. A pump that has ingested small debris past a torn basket will slowly pack the impeller and lose flow. Pumps and filters explained covers what the gauge is telling you.
Noises
- High-pitched scream or whine. Motor bearings. The pump still works but will get louder and eventually seize. A motor or a full pump replacement is coming.
- Rumble with poor flow. Cavitation. The pump is starved on the suction side and vapor bubbles are collapsing inside it. Find the restriction. Left alone, cavitation destroys the impeller.
- Rattle or grinding. Debris in the impeller, or a failing bearing. Shut down and inspect the basket and impeller.
- Hum with no rotation. A seized motor or a bad capacitor. Do not leave it humming; it will burn out.
- Louder than it used to be, otherwise fine. Often the pump is simply running at a higher speed than it was, or the pad has shifted. Check the schedule and the mounting.
Water at the pump
A drip from under the motor where it meets the wet end is the shaft seal. It is a repair, not an emergency, but it will get worse and can let water into the motor. A drip from a union or plug is a gasket or o-ring. A wet pad with no obvious source is worth investigating soon; leak detection and repair covers how.
Variable-speed pumps
These have their own diagnostics on the display and will show a code for overheating, a blocked impeller or a communication fault with the automation. They prime the same way, and they can prime poorly if the priming speed in the settings is too low for the suction lift. Check the settings before assuming a fault. Variable-speed pumps covers what they do differently.
What to leave to a technician
Motor and bearing replacement, shaft seals, capacitors, and anything electrical. Underground suction leaks need pressure testing to locate. A pump that has been run dry needs inspection before it is trusted again.
Preventing most of it
Keep the water level up. Empty baskets weekly. Lubricate the lid o-ring each time the basket is cleaned. Keep the pad clear so the motor can cool. Replace a torn basket the day you notice it. What wears out and when sets expectations for the pump's life.
We install and troubleshoot equipment on the pools we build across the Triad, including Thomasville and Wallburg. Reach out for a free consultation if you are planning a build or an equipment upgrade.