Engine Coolant Thermostat (RT1139) by Motorcraft®. Temperature: 190F. With today’s complicated automotive engines, it is crucial to have the right cooling system components for accurate temperature control, pressure relief, and gasket seals. Motorcraft is the way to restore the performance of your vehicle. Designed specifically for your vehicle, Motorcraft products meet stringent Ford Motor Company standards and feature OEM quality without the OEM price.