In this process, where possible, the thermostat is removed from the engine. An engine cleaner is added to the cooling system. We let the engine run with the heater turned on until the system has warmed up. We then turn off engine and then pressure flush the entire system in the reverse manner so that the coolant that normally flows through the entire process removes any loose scale build up and also removes all of the old coolant and dirty water. We replace the thermostat and add new coolant and new water. We run the engine and check that the entire cooling system is operationally functional and working to its optimum. This process should be completed every 18 months to 2 years.