Maximize performance and efficiency of a fresh water cooled engine by running it at the optimum temperature. A failed thermostat can cause an engine to run at outside of its optimum temperature and can adversely affect performance and efficiency. The fix can be as simple as replacing the thermostat. This Sierra thermostat is engineered with a temperature rating of 160 degree and is compatible with many Mercury and Crusader marine engines. Sierra parts are engineered to meet or exceed the specifications of marine engine manufacturers and earned the confidence of the marine industry. Boaters and technicians can be assured a Sierra part will fit right the first time and restore function to OEM specifications.