Our premium 143ºF thermostat kit is engineered for wide compatibility and superior performance across Mercury 40–300 HP two-stroke outboards (OEM Part Number 75692) and OMC, Johnson, and Evinrude outboards (OEM Part Number 5005440) ranging from 9.5 to 235 HP.
Whether you're performing routine maintenance or upgrading your cooling system, this kit ensures precise temperature regulation, improved fuel efficiency, and enhanced engine protection in all conditions.
Precise Temperature Regulation – 143º Fahrenheit Operation
At the heart of your outboard’s cooling system, the thermostat opens and closes at 143ºF to maintain the optimal engine temperature. It stays closed during startup to promote faster warm-up, then opens at the target temperature to allow coolant to circulate and prevent overheating.
This consistent regulation ensures your engine runs within its intended temperature range, critical for performance and reliability—especially in colder water environments.
Improved Engine Efficiency and Longevity
Operating your engine at its designated temperature range improves fuel efficiency, reduces emissions, and supports more complete fuel combustion. Running too cold leads to poor throttle response and carbon buildup, while overheating can cause serious internal damage. Our high-quality thermostats ensure your outboard stays within its thermal sweet spot, helping to extend engine life and maintain optimal performance over time.
Premium Materials – Built to Last
Each thermostat in this kit features a stainless steel body for corrosion resistance and a copper thermal element for accurate, fast response to temperature changes.
These marine-grade materials are ideal for withstanding harsh freshwater or saltwater conditions. Compared to standard replacements, these components offer longer service life and consistent performance under pressure.
Kit Includes: Two (2) 143ºF Thermostats and Two (2) Thermostat Seals
This complete replacement kit includes two thermostats and two high-quality seals, ensuring a snug, leak-free fit. The design matches original equipment specifications, making installation straightforward and reliable for a wide range of outboard models.
Cross-Compatible with Multiple OEM Part Numbers
Our thermostat kits are a direct replacement for a wide range of OEM part numbers, ensuring compatibility with multiple outboard brands. For Mercury/Mariner engines, it replaces part numbers 75692Q2, 75692T3, 18-0182, 30610, 306162, 310058, 508633, 62386, 62386B, 62386001, 777381, 8M0204714, and 9-60002.
For OMC, Johnson, and Evinrude outboards, it is compatible with part numbers 13010, 18-3543, 377148, 377612, 378065, 393659, 434841, 437414, 5005440, 62981, 66850, 75692, 75692B, 777260, 8M0175326, 8M6010302, 833072003, 833072004, 9-4030, 9-43019, and 9-43101. The primary manufacturer item reference is 5005440.
For technical support, contact Mike Hill at +1-714-697-1716 or mike@buckshotracing77.com