The Cummins Thermostat 5274887 (also compatible with part number 3968559) is a precision-engineered cooling system component designed specifically for Cummins 6C8.3 and L8.9 series diesel engines. This genuine-quality thermostat maintains optimal engine operating temperature by regulating coolant flow between the engine and radiator. With an accurate opening temperature of 82℃, it ensures rapid engine warm-up during cold starts and stable temperature control under varying load conditions. The robust construction features a high-quality wax element and stainless steel components that provide reliable performance and extended service life. This thermostat plays a crucial role in optimizing fuel efficiency, reducing emissions, and protecting engine components from thermal damage in heavy-duty applications.