Dear Tom and Ray:

My daughter has a 1987 Renault hatchback with 57,000 miles. It stopped running due to a broken timing belt. But the repair cost $900 because they said the valves were damaged. Can an engine design be that bad, or was this a repair rip off?
Bob

RAY: Even though it's hard to believe, it's the engine design, Bob. There are some engines, like this one (and Hondas, Nissans, early Ford Escorts to name a few), which destroy their own valves when the timing belt breaks.

TOM: The timing belt is responsible for making the valves open and close at the right times. Inside the cylinder, the piston is moving up and down very fast. When it's down, the valves (which are at the top of the cylinder) open INTO the cylinder, and allow gas and air to come in and exhaust to go out. But when the piston comes flying back up to the top, those valves had better be closed and out of the way. If not....ba-boom! They get crunched.

RAY: And on some cars--like your '87 Renault--when the timing belt breaks, the valves just stop in whatever position they happen to be in. So inevitably, some of them are open, and the pistons crush them. On other--more thoughtfully designed--cars, the valves just float freely when the timing belt breaks, so they just get pushed out of the way rather than mangled.

TOM: So why didn't Renault warn you about this? Well, I'm sure that if you look in the Renault owner's manual (assuming you can translate from French), you'll see that they recommend changing the timing belt at something like six years or 60,000 miles. They estimate the timing belt will last at least that long. And they assume that if you change it then, you'll avoid this sort of disaster. Obviously, in your case, they were right about the years, but they were off by 3,000 miles. Oh, well. C'est la vie!