Check the level of coolant in the coolant recovery tank. After has cooled, remove the radiator cap. Coolant should be at the full level in the radiator. Fill with coolant mixture if low before pressure testing. Do not remove the radiator cap if the engine is hot.
Pressure test the cooling system.
Wet the gasket on the tester with coolant, then pump to the pressure rated on the radiator cap. The entire system should hold the pressure rated on the cap unless there is a leak. Look under the car, inside the car around the heater area, and under the hood around the hoses, connections, water pump area, etc. for any signs of leakage or swelling of soft hoses. Check the radiator cap using the cooling system pressure tester and pump until the pressure is equal to the pressure stamped on the cap. Pressure should hold if it is good.