3866
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DESCRIPTION
Mechanical Seal 3866 — Type 166 / T-16 (5/8″) | PS-3866 Equivalent
Equal to industry standard 3866 / PS-3866.
Direct-fit Type 166 / T-16 single-spring seal for pool/spa and small-pump applications—upgraded with Viton® elastomers and a machined carbon/ceramic face set for longer service life.At-a-glance specs: 5/8″ shaft • 1.187″ × 0.343″ cup seat • Machined carbon/ceramic faces • Viton® elastomers
Why choose 3866 (PS-3866):
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T-16 footprint for quick, drop-in replacement
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Viton® handles higher chlorine, heat, and chemicals better than Buna
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Machined carbon face for smoother sealing vs. molded carbon
Upgrades / Alternatives (same footprint):
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100 — Basic (Buna)
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957 — Premium carbon face (Buna)
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100cv — Molded carbon
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100cvss — Silicon Carbide / Silicon Carbide / Viton
Explore our full lineup of Single Spring Seals—PS replacements, pool/spa seals, and our SPS line.
Looking for more? Shop Pump Repair Kits, Parts & Accessories, and Pre-Cut Gaskets.
Have questions? Check out our Pool/Spa Small Pump Guide or call us anytime—we’re here to help.
Please click “specifications” below for OEM numbers and Pump Nameplate Data
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SPECIFICATIONS
OEM numbers: 4547 , 17351-0102
Brands: Anthony & Sylvan Corporation , Pentair Pool Products
Nameplate Data: AJ Series , L-Series™
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PHYSICAL PROPERTIES
Seal House Type 166
Our Type 166 configuration combines the best design elements we’ve refined over the years to deliver superior reliability and performance.Key advantages include:
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Crimped rotary face with positive drive — securely held in place to prevent dislodgement during installation.
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Full metal retainer with positive drive — ensures strength and long-term durability.
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Full rubber bellows construction — provides complete sealing along both the shaft and face, rather than relying on a small O-ring or partial gasket.
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Quality materials — delivers extended service life.
Compatibility & upgrade:
The Type 166 is designed to replace most small seal types commonly used in pool and spa applications, including Type 16, G, A, 6, AV, 2100, and more. Even in its basic form, this seal is a significant upgrade over standard “pool” seals typically available on the market.
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