Is the secondary water pump possible to flow even the thermostat is closed? I was hoping that I could put a switch, sot I could switch on the pump inside the car when I want. Someone will ask anyway, so hear is the answer why: Its winter coming, and here in Finland we can have days with -30 degrees so I'll put an engine heater which heats the cooling water. The water should flow with its own when the temperature changes but unfortunatelly its not that case allways. That leads to problems when the coolant temp sensor heats up but the water temp isn't that high thorougly. So when the engine starts up and the water start to flow, the temp sensor freks out (hot/cold/hot/cold etc.) and causes very bad idling for a moment.