In brief: 5/8-inch replacement mechanical seal for Pentair inground and above-ground pool pumps. Pentair part number 354545S.
Water dripping between the motor and the pump housing?
This is the unmistakable symptom of a worn mechanical seal. The seal prevents water from traveling along the motor shaft: two polished faces, one stationary and one rotating, pressed against each other.
When it leaks, water runs over the motor’s front end bell, enters through the drain, and destroys the front bearing and then the windings. That’s how a repair costing a few dozen dollars turns into a motor replacement.
The most common cause is running the pump dry, even for just a few seconds: the polished faces heat up instantly and become scratched.
Official Pentair specifications
| Part number |
354545S |
| Size |
5/8 in. |
| Type |
Mechanical shaft seal |
| Application |
Pentair inground and above-ground pool pumps |
| Genuine part |
Yes, Pentair part |
Frequently asked questions
Is an occasional drip a problem?
Yes. A mechanical seal that starts leaking will never reseal itself. The leak gets worse, and eventually water reaches the motor bearing.
Should both faces be replaced?
Yes. Always replace the complete mechanical seal assembly: the stationary and rotating faces are lapped together at the factory. Replacing only one guarantees an immediate leak.
How can I prevent the next one from wearing out?
Never run the pump dry, even for a few seconds. Always prime it before starting, and keep the skimmer basket clear to prevent loss of prime.
Service on the North Shore
Piscines Geyser keeps Pentair parts in stock in Blainville and serves the Laurentians. Send us a photo of your setup if you’re unsure whether it’s the right fit: we’ll confirm before shipping.
