Cummins 3968559 Thermostat Assembly

The Cummins 3968559 thermostat is a temperature-sensitive valve designed to maintain optimal engine operating temperature by regulating coolant flow. It features a vented design with a 54.10mm diameter and opens at 76°C (169°F) or 82°C (180°F) depending on application. This genuine OEM component ensures reliable cold warm-up and prevents overheating in heavy-duty diesel engines. Constructed with precision-engineered body and high-quality sealing materials, the thermostat meets OEM specifications for durability and temperature control accuracy. It serves as a direct replacement for multiple Cummins part numbers including 3940632, 5284903, 4930594, 5274887, and 5337942. Compatible with Cummins C Series (6C8.3, 6CT8.3, 6CTA8.3) and L Series (L8.9, L9, QSL9, ISL9) engines used in construction machinery, heavy-duty trucks, and power generation equipment.