Overheating on 1999 Mercury Cougar

Why my cougar 1999 is overheating if the water pump and fans works properly, it doesn't have thermostat, radiator is clean. Also when the temp. gets half way the water gets out of the water container and the cap is new

by in El Paso, TX on September 23, 2010
1 answer
ANSWER by on September 23, 2010
If you are sure the thermostat, radiator is working efficiently, water pump actually does circulate coolant from the engine to the radiator, and the electric fan operates correctly I would check for 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-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.
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