I have a 2000 Subaru Outback
How do I know if I need a head gasket replacement? on 2000 Subaru Outback
There's a tester you can buy from NAPA called a block tester. With that tester you can determine if you have a blown headgasket.
I work on a lot of Subarus and I hate to say it but it is a common Subaru problem for your year. Best not to jump to conclusions. 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.
a cylinder leak down test. it will see if there is compression in the cooling system. that will determine if you have a head gasket issue.
What are the symtoms? Why are you think you need to replace the head gasket?