Century Pool Pump Bearing Replacement – How to Diagnose and Replace Worn Bearings

Understanding the Problem

Worn or failed bearings in a Century pool pump motor will cause grinding or squealing noises, vibration, shaft play, overheating, and eventually seizure of the pump. Bearings usually fail from water intrusion, age, or lack of lubrication (in older serviceable bearings). Below are practical diagnostic and repair steps you can follow. 1) Safety first - Turn off and lock out the circuit at the breaker. Confirm power is off with a multimeter. Drain and isolate the pump from the plumbing so you can lay it on its side. Wear safety glasses and gloves. 2) Initial diagnosis (fast checks) - Listen: start the pump briefly (if safe) and note any grinding, rumbling, squeal or knocking coming from the motor end. Loud bearing noise usually comes from the motor endbell. - Feel/play: with power off, remove the pump strainer lid and impeller housing and try to rotate the shaft by hand. Roughness, grinding, or lateral play (shaft wiggle) indicates bearing wear. - Inspect debris: check the strainer basket and volute for metal shavings or black/bronze dust — a sign of bearing or seal failure. - Check temperature: a very hot motor after short run is a sign of bearing drag or electrical problem. 3) Disassemble pump to access motor bearings - Remove electrical box cover and disconnect motor wiring after noting connections or taking a photo. Unbolt the motor from the wet end and remove the diffuser/impeller per the model manual. - Remove motor endbells: support the motor, unbolt the endbells (front and rear). On many motors the front endbell (shaft/impeller side) covers the lower bearing and the rear endbell covers the upper bearing. - Inspect bearings: spin the rotor by hand. If you feel roughness, hear grinding, or see shaft end play, the bearings must be replaced. 4) Bearing removal - Use an appropriate bearing puller and driver. On many motors you'll press or pull the bearings off the shaft; do not pry them off the rotor journal — use a puller to avoid damaging the rotor. - If bearings are pressed into the endbells, heat the endbell (with a heat gun) to expand the housing slightly and drive the bearing out from the opposite side using a bearing driver. - Clean the rotor journal and endbell bores; inspect the shaft for scoring. Deep grooves may require shaft replacement or turning. 5) Install new bearings - Buy identical-size replacements (sealed bearings like 6203-2RS, 6204-2RS, or the exact OEM numbers for your motor). Press new bearings onto the shaft using a bearing driver that contacts only the inner race, or press them into the endbell contacting only the outer race. Avoid hitting the bearing seals or races directly. - If the pump uses insulated bearings or a sleeve between bearings, reinstall per factory spec. 6) Replace mechanical seal and gaskets - Any time you split the wet end you should replace the mechanical seal and gaskets. Old seals commonly leak after bearing repair. 7) Reassemble and test - Reinstall endbells, torque to spec, remount the motor to the pump housing, rewire using your photos, and refill the pump. Restore power and run briefly to confirm quiet operation, no vibration, and no leaks. - Check amperage draw — it should match the nameplate. Excessive draw after repair indicates binding or misalignment. 8) Final checks and preventive maintenance - Align motor and pump face properly, ensure shaft coupling is clean and straight, and verify all fasteners are tight. Consider installing a flexible pad or mount to reduce transmitted vibration. Safety note: Always disconnect power at the breaker and verify with a meter before working. Mechanical work can release stored energy in springs and couplings; support heavy parts to prevent injury. If you are not comfortable using a bearing press/puller or working with electrical wiring, hire a qualified technician.

Common Symptoms

Loud grinding or squealing from motor, increased vibration, shaft play, reduced flow or pump seizure, overheating motor, metal shavings in pump basket, frequent seal leaks after repair.

Common Causes

• Water or chemical intrusion into bearing leading to corrosion
• Normal wear from age and hours of operation
• Misalignment or excessive load on the shaft/impeller
• Lack of lubrication (older serviceable bearings) or failed sealed bearings
• Electrical issues causing motor overheating and bearing damage

Popular Parts That Fix This Problem

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Frequently Asked Questions