Two (2) Thermostats 143º F  and two (2) Seals for Mercury 40 to 300 hp two-stroke outboards.
 
A 143-degree thermostat in a Mercury Marine outboard helps regulate the engine's operating temperature.
 
Here’s how it works and why it's used:
 
Temperature Regulation: The thermostat opens and closes to maintain the engine's temperature around 143 degrees Fahrenheit. When the engine is cold, the thermostat remains closed to allow the engine to warm up quickly. Once the engine reaches the specified temperature, the thermostat opens to allow coolant to flow and maintain the temperature.
 
Optimal Performance: Keeping the engine at an optimal operating temperature ensures efficient combustion and performance. An engine that runs too cold can be less efficient and may not burn fuel completely, leading to increased emissions and potential buildup of deposits. Conversely, an engine that runs too hot can suffer from overheating, which can cause damage to engine components.
 
Engine Longevity: Maintaining a stable temperature helps in reducing wear and tear on the engine. Proper thermal management reduces the risk of overheating, which can cause serious engine damage, and avoids the issues associated with running too cold, which can include increased friction and wear.
 
Fuel Efficiency: Proper temperature regulation also contributes to better fuel efficiency. Engines that run at their designed operating temperature use fuel more effectively, leading to better mileage and performance.
 
In summary, a 143-degree thermostat in an outboard motor ensures that the engine operates within its optimal temperature range, promoting efficiency, performance, and longevity, particularly in cold water areas.

Mercury Part Numbers: 75692Q2, 75692T3, 75692Q2, 18-0182, 18-0182, 30610, 306162, 310058, 508633, 62386, 62386B, 62386001, 777381, 8M0204714, 9-60002, 62386