Thanks for the replies, gents, but I found out what the problem was, much to my chagrin.
Turns out I'm leaking water into the engine. The problem was so slight, the guy said, that it was hardly noticeable and probably misdiagnosed as a faulty water pump and thermostat trouble. I noticed some oil goo on the carport a few days ago and took it straight to the shop. I'm pretty clueless about cars, but I know oil goo + cooling problems = big trouble.
Yesterday afternoon he started it up and to move it into the garage and the funky exhaust started.
Well...I
had big plans for Christmas, eh?
