Pentair Centrifugal Pump Shaft Seal | U109-433SS
Pentair
SKU: U109-433SS
Pentair U109-433SS Shaft Seal (1-1/4") – For Sta-Rite C/CC Series & D Series Commercial Pumps (3 HP & 5 HP)
The Pentair U109-433SS is a replacement mechanical shaft seal (commonly referenced as a 1-1/4" shaft seal) used in select Sta-Rite / Pentair commercial pump models. This seal is installed where the motor shaft passes through the pump seal plate to help prevent water from leaking along the shaft into the motor. Replacing a worn shaft seal is a common fix for pump leaks that appear at the motor-to-pump connection area.
Key Details
- Part Number: U109-433SS
- Part Type: Mechanical shaft seal
- Seal Size: 1-1/4" (commonly listed)
- Typical Seal Material: Buna (rubber components) with standard mechanical seal faces
- Primary Function: Helps stop leakage at the motor shaft / seal plate area
- Replaces: U109-220 (older part reference)
Common Compatibility
- Sta-Rite / Pentair C Series and CC Series centrifugal pumps (commonly 3 HP & 5 HP applications)
- Pentair D Series commercial pumps
- Important: Always confirm your pump model and horsepower using your parts diagram to verify this exact seal is correct.
Common Signs the Shaft Seal Needs Replacement
- Water leaking from the area between the pump and motor (seal plate / motor bracket area)
- Dripping or spraying that increases when the pump is running
- Repeated moisture around the motor base (after confirming it is not plumbing-related)
- Seal replacement is recommended any time the pump is opened for major service (impeller, diffuser, seal plate)
Installation Notes
- Turn off power at the breaker before servicing the pump.
- Mechanical seals have precision faces—keep them clean and avoid touching the sealing faces with oily/dirty hands.
- Inspect the shaft sleeve and sealing surfaces; a grooved or corroded sleeve can cause a new seal to fail early.
- Verify there is no wobble in the motor bearings; excessive shaft play can shorten seal life.
- After reassembly, confirm the pump primes normally and check for leaks during the first run.
Related Products
- Search: U109-433SS Shaft Seal
- Search: C23-58 Shaft Sleeve
- Search: C20-101 Sleeve Gasket
- Search: Sta-Rite C Series Pump Parts
- Search: Sta-Rite CC Series Pump Parts
- Search: Pentair D Series Pump Parts
- Search: Pool Pump O-Ring Lubricant
Installation & Maintenance Tips
- Fix the cause, not just the leak: Overheating (running dry), poor water chemistry, or misalignment can shorten seal life.
- Replace the shaft sleeve if needed: A worn sleeve can cut into a new seal and cause repeat leaking.
- Keep the pump from running dry: Loss of prime can overheat the seal faces and damage the seal quickly.
- Address drips early: A small leak can lead to motor damage if water reaches the bearings or electrical components.
- O-ring lube note: Use silicone lubricant on housing O-rings/gaskets only—do not grease mechanical seal faces.
Questions about returns? View our return policy.
Hours Of Operation:
Monday - Friday: 8:00 am to 4:00 pm Phoenix Time
Saturday and Sunday: Closed
- Orders costing more than $300 WILL be required to have signature confirmation upon delivery.
- Handling time is typically only 1 day.
- Any item ordered after 1pm Phoenix time, may not ship same-day.
- Call us if you require expedited shipping and we can give you quotes based on your needs.
Return Policy:
- All products, except as noted below, are eligible for return up to 30 days after receipt of item.
- For returns, an RMA form must be filled out HERE or customers can call for additional help.
- Shipping costs will be deducted from all returned items.
- Any item that is missing accessories, original packaging, or is not returned in the same condition that it was received in, may be subject to a re-stocking fee up to 100% based on the condition we receive it in.
- Items broken, damaged, or inoperable due to installer error will not be refunded.
- Fill out the return form or give us a call to obtain an RMA and return shipping label.
- There are no returns on the Pentair Colorsync 618031
- No returns on pool cleaners.
- No returns on opened seals and o-rings.
- No returns on capacitors.
- If a light is returned because it "doesn't work" and it tests fine, the cost to ship and a re-stocking fee will be deducted from the refund.
- All products denied upon arrival at customers house WILL be charged the cost to ship.
- Visa Gift Card Promotions: Gift cards are sent within 14 days of the order. When accepting the Visa Gift card, you agree that if your order is returned or refunded, this amount will be deducted from the refunded amount. All Visa Gift cards are sent via email in an E-Gift Card format and are non refundable.
Related Products