This way, the thermostat is inspected and the insides of the hoses are inspected for deterioration. Then it is reassembled.
Filling it is done by removing the upper rad hose -leaving it connected to the engine. Fill the hose to the top with coolant and then reconnect it to the radiator. The remainder is then poured into the overflow container to fill the other side of the thermostat. This ensures that coolant is on both sides of the closed thermostat. Now when the engine is brought up to operating temperature, the thermostat opens and lets the minor air bubbles out to the overflow tank. When it cools you will see how much more fluid you need to add to the system.
