AMT 3360-070-90 Neoprene Flapper Valve Assembly
The AMT 3360-070-90 is the genuine neoprene flapper valve assembly for AMT diaphragm pumps, listed for both the 335/336 and 337/338 series. It is the check valve that gives a diaphragm pump its direction — without it the chamber would simply push liquid back out of the suction on every discharge stroke.
Neoprene is a deliberate material choice for this job rather than a generic rubber. It has a good balance of qualities that a flapper valve specifically needs: enough flexibility to seat cleanly against a surface that is never perfectly flat, enough toughness to survive thousands of impacts an hour against its seat, resistance to ozone and weathering so it does not perish while the pump sits idle, and reasonable tolerance of oils and mild chemicals. A flap that is too soft will invert under pressure; one that is too hard will not seal.
The end of a flapper valve’s life is easy to recognise once you know what to look for: a glazed, stiff surface; a crack or tear where it hinges; or a permanent curl that stops it lying flat. Any of those and the valve leaks backwards on every stroke, and the pump quietly delivers a fraction of its rated output while sounding entirely normal. Replace the valves as a set and confirm the part number against your parts breakdown before ordering.
Key Features
- Genuine AMT (Gorman-Rupp) service part — assembled to the original specification
- Neoprene construction — flexible enough to seat, tough enough to survive constant impact
- Resists ozone and weathering, so it does not perish while the pump stands idle
- Listed for AMT 335/336 and 337/338 diaphragm pump series
- Direct replacement — no trimming or fitting required
Applications
- AMT 335 and 336 Series diaphragm pumps
- AMT 337 and 338 Series diaphragm pumps
- Restoring output on a diaphragm pump that has gone weak
- Replacing a flap that has glazed, cracked at the hinge or curled
- Marine, dockside, sump, dewatering and construction service
Specifications
- Brand: AMT (Gorman-Rupp)
- Manufacturer Part Number: 3360-070-90
- Part Type: Flapper valve assembly (check valve)
- Material: Neoprene
- Pump Series: AMT 335/336 and 337/338 diaphragm pumps
- Service Note: Wear item — replace as a set when output drops
- Condition: New
Not sure this is the right part? Send us a Picture of the pump plate on your pump and the CLR Marine team will confirm the correct part before you order.
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