Properties:

A metallic and/or non-metallic device with various ports on one end and a wrenching facility between ends. The opposite end may be threaded and contain a temperature probe. It is normally located on the upper engine block, on the water jacket or screwed into the upper radiator tank. Depending on individual temperature calibration it opens or closes various ports in order to channel manifold vacuum to devices which activate, de-activate or modify functions in fuel economy, cold temperature override, thermal ignition control, exhaust gas recirculation and other systems by sensing engine water temperature.