Pool pumps leak in several places, and most of them are inconvenient rather than serious. One is different. If water is coming from the gap between the motor and the pump body, where the shaft passes through, stop reading advice about lid o-rings. That is a mechanical shaft seal, and it is on a clock.
Why this one is urgent
The shaft seal is the only thing separating pool water from the motor's front bearing. Once it fails, water runs along the shaft and into the bearing housing. The bearing rusts, then it gets noisy, then it seizes — and a seized bearing usually takes the motor with it.
A shaft seal is a modest part. A replacement motor is the single most expensive component of the pump. The entire economics of this repair depend on doing it early.
Confirming it is the shaft seal
- Location. The drip originates at the seam between motor and wet end, not at the lid or the unions.
- Timing. Classic shaft seal failure leaks while the pump is running and may stop when it is off. A lid o-ring leak often does the reverse, weeping when the pump stops and the system loses vacuum.
- Rust streaks. Look at the motor face and the pad underneath. Brown staining below the seam is a seal that has been leaking longer than you have noticed.
- Noise. A growling or whining bearing alongside a leak means the damage has already started.
What a shaft seal looks like
It comes in two halves. A carbon rotating face mounted on a rubber bellows with a spring, which pushes against a white ceramic seat held in a rubber cup. The two polished faces run against each other, and that contact is the seal.
This is why you must never lubricate the seal faces. Silicone on the carbon or ceramic will cause them to slip and the seal will leak from new. Lubricant goes on the rubber cup and o-rings only.
Find your seal by pump
Shaft seals are pump-specific. A few of the most common:
- Hayward PowerFlo Matrix and Power-Flo LX — SPX1500KA. See the Matrix guide and the LX guide.
- Hayward Northstar (2008 and later) — SPX4000SA2, also listed as SP4000, SP4000X, SP3200EE, SP3200X, SP3600, SPX3200SA.
- Hayward MaxFlo II, MaxFlo XL and VS, Booster 6060 — SPX2700SA, also SPX1250XZ2C, SPX1250XZ2.
- Pentair and Sta-Rite Challenger, SuperFlo, SuperMax, VS, Pinnacle, Dynamite, Dynamo, Dynatron, Triton — 354545, also 354545S and 17304-0100.
- Pentair and Sta-Rite Dyna, Max-E-Pro, Dura-Glas II, Maxi-Glas II — U9-358, also U109-358SS, U109-372SS, 37407-0009, 37400-0027S, 17351-0101S.
If your pump is not listed, or you are unsure which variant you have, contact us with the model number from the motor plate. We would rather confirm the fitment than have you order twice.
Do the whole wet end while it is apart
Getting to the shaft seal means separating the motor from the wet end. At that point every other o-ring in the pump is exposed and has aged under identical conditions. Our rebuild kits bundle the shaft seal with every o-ring and gasket for the specific pump, plus lubricant and instructions — and cost little more than the seal on its own.
Before you reassemble
Every o-ring in these kits seats better and lasts longer with a food-grade silicone lubricant. Dry o-rings pinch, twist and take a set, which is how a brand-new seal starts weeping within a season. A thin film is all you need.
Aqua Flex Food Grade Silicone Lubricant is what we use and what ships in our kits. Apply it to o-rings only — never to the polished faces of a mechanical shaft seal. Those faces need to run dry and clean against each other, and lubricant on the carbon or ceramic will cause the seal to slip, overheat and leak.
Beaver Island Parts Company is not affiliated with, endorsed by, or sponsored by any equipment manufacturer named on this page. All brand names, model numbers and part numbers are the property of their respective owners and are used here solely to identify the equipment our replacement parts fit.