Dometic SeaLand 385311316 S-Series Vacuum Pump Valve Adapter

SeaLand 385311316 S-Series Pump Valve Adapter

When a vacuum toilet system starts losing suction or won't hold vacuum properly, the valve adapter is often the first place to look. The SeaLand 385311316 is a purpose-built replacement adapter designed to work with all S-Series vacuum pumps and generators, giving boat owners and RV owners a straightforward way to restore reliable performance without replacing the entire pump assembly.

This adapter connects to the duckbill valve using right-hand threads, and the vacuum seal comes from the duckbill valve's built-in O-ring rather than thread sealant. That's an important detail for anyone doing the install themselves: skipping Teflon tape isn't an oversight, it's actually necessary, since tape on these threads can damage the fitting or compromise the duckbill valve's seal. Made from corrosion-resistant material suited to the wet, high-cycle environment inside a marine or RV sanitation system, this part is built to hold up over repeated use.

Whether the system is a compact S12 pump on a small boat or a larger S24 setup paired with a VG2 or VG3 vacuum generator, this adapter fits the same S-Series architecture across the lineup. It's also sold under a few different reference numbers over the years, including legacy number 385311226, so it's worth double-checking part compatibility against the pump's original documentation before ordering.

Key Features

• Right-hand (RH) thread design for secure, consistent connection
• Vacuum seal provided by the duckbill valve's built-in O-ring (no Teflon tape required)
• Corrosion-resistant construction for long-term durability in wet environments
• Compact, low-profile design that fits within existing pump housings
• Straightforward installation for DIY repairs

Applications

• Dometic/SeaLand S-Series vacuum pumps (S12, S24)
• VG2 and VG3 vacuum generators
• Marine vacuum toilet (Vacuflush) systems
• RV blackwater and holding tank sanitation systems
• Boat and RV plumbing repair and maintenance

Specifications

• Part Number: 385311316
• Legacy Part Number: 385311226
• Sealand Reference Number: 600347801
• Thread Type: Right-hand (RH)
• Material: Corrosion-resistant composite
• Port Size: 1.5 in (matches 1.5 in duckbill valve used on S-Series pumps)
• Sealing Method: Duckbill valve integrated O-ring
• Compatible Systems: S-Series pumps, VG2, VG3 vacuum generators

FAQS

Q: Do I need Teflon tape when installing this adapter?
A: No. Teflon tape isn't recommended on this adapter's threads. The vacuum seal comes from the duckbill valve's built-in O-ring, and tape can actually damage the fitting or the valve.

Q: Will this adapter work with a J-Series vacuum generator?
A: No. J-Series generators (VG4) use 2 in duckbill valves, while this adapter is built for the 1.5 in duckbill valves used in S-Series pumps and VG2/VG3 generators.

Q: How do I know if this part is compatible with my older Sealand pump?
A: This adapter also covers legacy part number 385311226, so it's a suitable replacement for older S-Series pump builds using that original part.

Q: Can this adapter be used in both marine and RV vacuum toilet systems?
A: Yes. It's designed for any S-Series pump or VG2/VG3 generator setup, whether installed on a boat or in an RV sanitation system.

Q: What's a sign that this valve adapter needs replacing?
A: Reduced suction, difficulty holding vacuum, or a noticeable air leak near the pump's duckbill valve area are common signs the adapter or its seal has worn out.