Engine acting up? Don’t let a faulty part keep you off the water. This genuine Mercury Marine THERMOSTAT ASSEMBLY restores reliable performance and gets you back to what you love.

Engineered to Mercury’s rigorous OEM standards, this thermostat ensures reliable operation across all engine RPM ranges. Part number 8M0090819 is manufactured to exact Mercury Marine factory specifications for precision installation and optimal performance. Constructed from premium marine-grade materials designed to withstand harsh saltwater and freshwater environments.

Smart boat owners know: buying cheap parts twice costs more than buying genuine Mercury once. Part 8M0090819 delivers long-term value through superior materials and precision manufacturing.

Compatible Mercury Marine Engines

FITS: 65-115HP MARINER, MERCURY (EFI)

• Fits MARINER, MERCURY 65-115HP engines
• Compatible HP: 65HP, 75HP, 80HP, 90HP, 100HP, 115HP
• Model types: EFI
• Covers 12 serial number ranges
• Configurations: Jet Drive, Outboard
• OEM genuine Mercury Marine part

COMPLETE SERIAL NUMBER COMPATIBILITY:

65HP Models

• 65HP JET (Mercury)

75HP Models

• 75HP EFI (Mariner)
• 75HP EFI (Mercury)

80HP Models

• 80HP EFI (Mariner)
• 80HP EFI (Mercury)
• 80HP JET (Mercury)

90HP Models

• 90HP EFI (Mariner)
• 90HP EFI (Mercury)

100HP Models

• 100HP EFI (Mariner)
• 100HP EFI (Mercury)

115HP Models

• 115HP EFI (Mariner)
• 115HP EFI (Mercury)

Don’t know where your serial number is? Our quick reference guide shows exactly where to find it on Mercury Marine engines.

Verification & Support

Want to verify compatibility for part 8M0090819? Use our parts finder tool for instant confirmation. Still have questions? No problem – use the contact buttons at the bottom of this page to reach us by text, call, or email

Serving boaters for over 40 years. Great prices, quick delivery – your parts ship fast.