Have the cooling system pressure tested to look for leaks. The way an automotive shop would locate the leak is by removing the radiator cap 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.
Next check for a blown head gasket or a reason why coolant could enter the combustion process. 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-lis75500.aspx. Carbon Monoxide is only present if there is a blown head gasket or cracked cylinder head. http://www.arrowheadradiator.com/head_gasket_or_combustion_leak_test.htm 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.
well ive been a mechanic for 10 years and have never seen anything like it its not leaking it its burning it and its about a quart every 2 hours ive crack checked the heads twice and replaced the head gaskets even though they were fine im not getting any compression in the cooling system im reading about 15 lbs at the most but thats normal at running temp and i know its coming out of the tail pipe i can smell it but it runs like its a new engine this is my personal vehicle thats why i cant figure it out
Have you checked the intake for leaks, by chance?