Beer, A lot of times when the timing belt snaps, it pretty much takes the engine with it. Do a google search and you can see pictures of what used to be recognizable as car engines. Your mechanic probably has a hunch that if the head gasket isn't gone already, it may go soon - pretty much making your repairs done beforehand useless. As much as I hate car payments, we were put in a similar position and are dumping our old car this week. I agree with his hesitation and say go with another car. Besides, rates are really low right now.