So I'm working on my friend's 97 Mercury Mystique 4 cyl. It has been overheating and losing coolant. I looked at it briefly yesterday and found that there was oil sitting on the spark plugs. It hadn't been run in a week, and it wasn't starting. I changed out the spark plugs and it started right up. I drove it out to my place, and by the time I got there (8 minutes away) it was already overheating. So I decided I'd start with the thermostat, and since its only $7 or so I just threw a new one in. I also pulled off the valve cover to see about the oil on the spark plugs, and the gasket looked pretty bad, so I changed that. Then, I noticed that the serpentine belt was completely shot. When I say shot, I mean it was the worst belt I have ever seen still on a car. It was completely split right down the middle. Anyway, I changed that out, started it up. I filled the coolant, drove it around a bit, and sure enough it overheated. Oh and also, I noticed where the car was leaking coolant from. I believe it is the water pump seal. I noticed it trickling down below the crank pulley. So here is my theory, and I just want to know what you guys think before I go tearing stuff apart again. I think that the water pump went bad and started locking up (maybe?) and burned up the belt. When the car overheated it melted the valve cover seal and the water pump seal. So what do you guys think? Also, where is the temp sensor for the gauge on this car. I think I may have forgotten to plug it back in. The temp. gauge isn't working anymore. Sorry for the length of the post, just wanted to get all the details in. Thanks in advance.