It has been discussed before. However, it is "doable" by a DIY'er. As a matter of fact, there is a separate post today talking about a head gasket problem. You may want to do a head job while are a it...
In the meantime, check all your rubber hoses going and coming from the the engine. NAPA sells a fluorecent dye that you put in the coolant and then follow it with a light but, if it is internal...you are out of luck!
