How do you check a head gasket?

• Remove and check your spark plugs, a cylinder that is burning coolant will generally show perfectly clean while the others will show normal gasoline burn patterns
• Pressure test the cooling system, this will expose any leakage to the exterior of the engine
• There is a special chemical and tool that actually detects exhaust gasses as they exit the cooling system. Most radiator shops and large auto repair shops have the system. You will have to pay for this test.

A good rule of thumb indicator's:Is the inside of the cooling system catch tank covered in black crud? if yes probably a bad head gasket.