Dishwasher Pump Shaft Seal for Model NODW731B – What Part Fixes Leaks Under the Machine
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Understanding the Problem
Brief explanation: The "shaft seal" on a dishwasher (often called the pump shaft seal, motor shaft seal or sump seal) seals the spinning motor shaft where it passes through the plastic metal sump/pump housing. On model NODW731B a failed shaft seal is the most common cause of water leaking from the bottom of the machine during or after a cycle. Step-by-step diagnostics and repair: 1) Safety first: turn off power to the dishwasher at the breaker and shut off the water supply. Confirm power is off with a non-contact voltage tester, and place towels to protect the floor. 2) Check easy indicators: remove the lower kickplate and run a short drain/fill cycle (power on briefly) to see where water appears. If water traces back to the center-bottom under the tub/pump area, the pump/sump area is suspect. 3) Inspect the sump/pump area visually: remove the lower dish rack and the plastic sump cover (if present). Look for water stains, mineral build-up, or oily residue around the motor shaft/impeller area. 4) Access the pump: pull the dishwasher out from under the counter enough to access the back and underside (disconnect water and power first). Lay the machine on its back on a towel to access the underside if needed. 5) Remove the wash pump/motor assembly: disconnect wiring harnesses and hose clamps, remove retaining screws/clips holding the pump to the tub. Keep track of fasteners and orientation of hoses. 6) Disassemble the pump/sump: many models have a snap ring or screws that hold the impeller/rotor and stationary seal. Remove the impeller/rotor to expose the shaft seal (two-piece: stationary seat in the housing and a rotating elastomer on the shaft). 7) Inspect the seal: look for torn rubber, scoring on the metal shaft, or embedded debris. If either seat or rotating portion is damaged, replace the seal. Also inspect the shaft for scoring—deep grooves may require replacing the motor rotor or full pump. 8) Clean mating surfaces: thoroughly clean the seal bore in the sump and the shaft/rotor area. Remove limescale and grit. Dry thoroughly. 9) Install the new seal: put the stationary ceramic seat into the pump housing square and flush; lubricate the rubber rotating part with a very small amount of dishwasher-safe silicone grease and slide it onto the shaft. Ensure the seal faces are correctly oriented (flat faces together). Use manufacturer instructions for any special tools or orientation. 10) Reassemble pump and test fit: reinstall impeller/rotor, snap ring or screws, and reattach pump to tub. Reconnect hoses and electrical. 11) Leak test: reconnect water and electricity, run a short cycle and watch for leaks around the pump. If leak persists, double-check seal orientation, condition of shaft, and that the stationary seat is fully seated. 12) Reinstall dishwasher into cabinet and re-secure. Safety note: Always disconnect power at the breaker and turn off the water supply before working. If you see signs of electrical damage, or if the motor shaft is badly scored, consider replacing the entire pump/motor assembly or call a professional. If you are not comfortable working under the dishwasher or handling motor wiring, hire a qualified appliance technician.
Common Symptoms
Water pooling under the dishwasher or on the floor after a cycle; visible leak at center-bottom of tub; motor runs but leaks; oil or dirty water around the pump area; intermittent leaks that worsen over time.
Common Causes
- Worn or torn rubber/elastic sealing surface due to age or abrasive debris
- Hard-water scale or grit preventing the stationary seat from sealing
- Scored or corroded motor shaft that prevents the rotating seal from seating
- Incorrect installation, damaged housing, or cracked sump allowing the seal to bypass
Popular Parts That Fix This Problem
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Helpful Repair Tip
Confirm the shaft seal is bad by looking for water pooling directly beneath the motor/pump area while the dishwasher is mid-cycle and by inspecting the impeller area for degraded rubber or visible leaks. A steady slow drip from the pump shaft when you spin the motor by hand (with water on but power off) is a strong sign the seal has failed.
Frequently Asked Questions
How long does it take to replace the dishwasher shaft seal?
For a confident DIYer with basic tools, 1–2 hours: 15–30 minutes to remove the dishwasher from the cabinet and access the pump, 30–60 minutes to disassemble, replace the seal and reassemble, and 10–20 minutes to run a leak test. If the pump housing or rotor is damaged you may need to replace the whole pump which can add time.
Can I replace just the shaft seal, or do I need to replace the entire pump/motor?
Often you can replace just the shaft seal if the stationary seat and the rotor shaft are in good condition. However, many manufacturers sell seal kits only with the pump or the seal may be hard to source separately. If the motor shaft is scored or corroded, or the seal bore in the housing is damaged, replace the full pump/motor assembly.
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