So I've plenty of other people's machines but this is the first I've owned and could use some help diagnosing a few problems. I've got an '02 S185. I had it checked out by a mechanic and he tells me I need a new head gasket. It doesn't seem to have any symptom. Starts easy, every time, sounds good, no smoke or smells, doesn't overheat. How can I identify if this actually needs to be done? Is it going to cause further engine damage if I continue using it in this condition? Problem two, rust in the coolant tank. Simply a matter of changing the rad? How to identify other parts that may need replacing? I'm only intend to put about 150 hours on it over the next year so if I can put it off and still use it without doing serious damage. I would appreciate any advice you guys have.