There is also some kind of temperature sensor at the back of the engine. It's not the termostat. Think it's only reading the engine temps to the ECU, but also does something with the temp gauge in the dashboard.
If it's giving faulty information to the ECU the engine can run lumpy.
If there is no pressure or there is no coolant running through the system (hense the hoses are cold), then something must be blocking the system somehow, but also an air buble can cause this issue, not sure if there is another way to bleed the air out except the coolant reservoir?
