GM Genuine Parts Engine Coolant Water Outlets are designed, engineered, and tested to rigorous standards, and are backed by General Motors. These engine coolant water outlets are housings that connect the radiator hoses to the engine, typically housing the engine coolant thermostat. For certain applications, the water outlet contains threaded holes or ports for sensors and switches. GM Genuine Parts are the true OE parts installed during the production of or validated by General Motors for GM vehicles. Some GM Genuine Parts may have formerly appeared as ACDelco GM Original Equipment (OE).