We've had a 1998 XC for about two years with no significant trouble. It has about 50,000 miles on it. Today, after sitting for three days, when my wife started it, it sounded exactly like a diesel. She said it ran fine the last time she drove it. It sounds to me like the noise (a loud tapping) is coming from the valve train. It is loudest at the top of the engine. Anybody got any thoughts on this? When we bought it used, it came with an extended warrenty that either just recently expired, or is about to in the next month or so (I'm going to check on that). It sounds bad enough that I definately wouldn't drive it. I'd be grateful for any advice or comments. Thanks, Joel