That drip coming from the back of the wet end — right where the motor meets the pump housing — is a shaft seal failure. It is one of the most common pool pump repairs, and it costs about $12 in parts. Leave it alone, and water wicks into the motor bearings within weeks. You are then looking at a $200 motor replacement instead. This guide walks you through the entire process: diagnosis, teardown, seal swap, and reassembly.
Before you order parts, make sure you are chasing the right leak. Dry off the entire pump with a rag, then run the pump for two minutes. Watch carefully. A shaft seal leak originates from the center of the pump body where the impeller shaft exits — not from the lid o-ring, not from the plumbing unions, and not from the drain plugs. If you see water coming from that dead center location, you have your answer.
Pro tip: A flashlight helps. The leak is often just a slow weep that only shows up as a wet ring around the shaft area after a short run cycle.
The shaft seal is a two-piece assembly: a ceramic seat that installs into the seal plate and a carbon face that rides on the shaft. Both pieces must be replaced together. Buy the kit, not just one half.
Turn off the pump at the breaker, not just at the timer. Close the suction and return valves so you do not need to drain the pool. Place a bucket under the pump to catch residual water when you open it up.
Remove the pump lid and basket. You will see 4–6 bolts around the perimeter holding the wet end to the motor housing. Remove them and gently separate the two halves. The impeller is now exposed.
Hold the motor shaft from spinning — insert a flathead screwdriver through the rear vent slots of the motor to brace the shaft — and turn the impeller counterclockwise. It is reverse-threaded on most pumps, so counterclockwise loosens it. Use the strap wrench if it is stubborn. Once the impeller is off, the seal plate and shaft seal are fully accessible.
Never use channel-lock pliers directly on the impeller vanes. You will crack it. Use a strap wrench instead.
The ceramic seat presses into the seal plate. Use needle-nose pliers or a thin screwdriver to pry it out carefully. The carbon face on the shaft side will slide off once the impeller is removed. Inspect both pieces — if you see cracks, chips, or scoring on the mating faces, the seal was overdue.
Use a rag to wipe the bore in the seal plate and the shoulder on the motor shaft. Any grit or debris will cause the new seal to leak prematurely. Take your time here. This is the most skipped step.
Press the new ceramic seat into the seal plate bore with your thumbs, using even pressure. It must seat fully and squarely. Slide the carbon face onto the motor shaft. Do not touch the polished mating faces with bare fingers — oils cause premature failure. Handle with a clean rag.
Thread the impeller back on (clockwise to tighten, since it is reverse-threaded). Torque the wet end bolts in a cross pattern to ensure even compression. Replace the lid o-ring if it looks flat or cracked — apply a thin coat of lubricant before reinstalling it. Reinstall the basket, lid, and open the valves.
Turn the pump on at the breaker and observe. No drip from the shaft area means a successful repair. Run for ten minutes and check again.
| Scenario | Cost | Time |
|---|---|---|
| Replace shaft seal now | $10–$18 | 45 minutes |
| Replace motor after bearing failure | $180–$320 | 2–3 hours |
| Replace entire pump assembly | $350–$700 | 4+ hours + plumbing |
The math is obvious. A shaft seal is a consumable part. Replace it at first drip, log it in PoolLens with the date and part number, and you will never be caught off guard mid-season.
PoolLens lets you log shaft seal replacements, set service reminders, and pull part numbers for any pump on your route. Free, offline-first, built for pros.
Open PoolLens Free →The shaft seal sits at the back of the wet end where the motor shaft enters. If the drip is coming from that center point rather than from the plumbing unions at the front, the shaft seal is the culprit. Dry everything off and run the pump briefly to confirm the exact origin.
No. Even a small leak lets water wick into the motor bearings. This causes premature bearing failure, which turns a $12 seal repair into a $200+ motor replacement. Replace the seal at the first sign of moisture.
Only if it is cracked or deeply scored. Inspect it when you have the seal out. A minor groove from the old seal can sometimes be cleaned up, but a visibly cracked plate should be replaced to ensure a proper seat.
Match the seal to your pump model, not just the size. Hayward, Pentair, and Jandy all have specific seal part numbers. Using a generic seal that is close but not exact can lead to early failure. Log your pump model in PoolLens to pull the correct part instantly.