Q&A

 Master

Check for a stuck thermostat, this will cause the car to boil and over heat when the car has been driven for ten minutes or so. A restricted radiator may also cause over heating if the the car is not cooling when driven at speeds above 30 miles an hour. The water pump or a failed cooling fan are primarily responsible for cooling the engine in traffic or at idle/ sitting at a traffic light.
The way an automotive shop would locate the leak is by removing the radiator car and attaching an adapter that screws on in place of the radiator cap. Something that looks like a bicycle pump with a pressure gauge attached to it is used to "pump up" pressure to simulate pressure generated when the cooling system is at operating temperature, the leak is then found sometimes it is obviously leaking from a coolant hose or cracked housing, failed gasket or water pump, sometimes the engines cooling system needs to be inspected from below or inspected using a mirror and flash light.
Your car may have a blown head gasket. The most accurate way to test for a blown head gasket on a gasoline engine is to test for the presence of carbon monoxide in the cooling system. Snap-On, Matco (part # CO 2000), and Napa sell a tool to check to carry out this test. Another link to a supplier of this tool is http://www.etoolcart.com/combustion-leak-detector-lis7550.... Carbon Monoxide is only present if there is a blown head gasket or cracked cylinder head. http://www.arrowheadradiator.com/head_gasket_or_combustio... I think the napa part number 700-1006. http://www.blockchek.com/instructions.htm . Signs of a blown head gasket are coolant loss (frequently have to top up the coolant level of the engine without seeing an obvious leak), experiencing over heating or rough engine running or the presence of white sweet smelling steam from the exhaust. A badly blown head gasket may allow engine coolant and oil to mix.