EVINRUDE OEM Diaphragm, Thermostat Cover – Part #0394408. Premium factory replacement from U.S. Boatworks, serving the marine industry since 1984.

Choose U.S. Boatworks for EVINRUDE parts you can count on. We keep #0394408 in stock and ready to ship — family-owned, expertly staffed, and committed to getting you back on the water fast.

Choose Quality, Choose OEM

• Factory-engineered for your exact engine
• Built to withstand marine conditions
• Better performance than generic parts

FITS: Verify compatibility for your engine — use our boat parts finder to find the right parts by model and year.

MARINE EXPERTS SINCE 1984

• Over 2 million parts ready to ship — including #0394408
• Largest selection of genuine OEM marine parts
• Need fitment help? See contact options below ↓

Need more boat parts? Check out our Boat Parts Finder to discover all the parts for your engine.