My wife and I were headed on vacation in Colorado several years ago--about a 10 hour drive. I had a local mechanic replace a leaky water pump in our '88 t-bird the week before in preparation for doing some mountain driving. He had just finished the job the afternoon before we left the next morning. We get about two hours from home and suddenly lots of noise starts coming from the engine compartment. I look behind us just in time to see a pulley rolling off the road into the ditch. Almost immediately the engine temperature starts to climb. Luckily, we just happened to be passing through a small town so we quickly pulled over at a restaurant to let the car cool down, see what was wrong, and figure out what to do. It seems the splendid mechanic that worked on the car had only replaced the bolts on the smog pump pulley finger-tight. After two hours of road time they worked loose and the pulley parted company with the car, taking the serpentine belt with it. We eventually went to an auto parts store and with the help of a great guy there I replaced the belt with a shorter one, bypassing the smog pump and the tensioner. I mean this belt was exactly the right size to run everything else and still be tight, even though we did have to pry it on over the last pulley--what are the odds of finding a belt that would do that. We should have gone and bought a lottery ticket. We decided to continue on the trip, and the repair worked for the whole week--probably 1500 miles of driving. I fixed it right when we got home, and of course the mechanic gave me a [censored] and bull story about what happened and how he was blameless. My shadow hasn't darkened his doorway since. Oh well, alls well that ends well.
