Q&A

 Master

In town traffic the radiator relies on the viscous fan hub to "lock up" the fan blade and draw air through the radiator to cool it. Once on the freeway rush air flowing through the radiator alone should be sufficient enough to keep the coolant in the radiator cool and the water pump circulates that through the engine block. You could have a bad water pump, you could have a restricted or inefficient radiator. If you don't have steam coming out the radiator or coolant loss that lessens the chance of a blown head gasket. Is your radiator cap good? 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.