I have a 97' RS Eclipse 2 door with a ticking sound from the engine?

This engine sound starts to click in neutral, when accelerating, reverse, and pretty much stays consistent in sound. The clicking just started a few days ago. I took the vehicle to a mechanic and he told me the clicking sound my be from a bad valve hitting metal. He said it sounds like a misfire and when he says that I need a new engine. He said the only way for him to find out the problem for sure is by taking the engine apart. He sounded pretty positive that by the sound and since it is coming from the engine it means the engine is bad.