Questions and Answers

Why Use Timing Belts And Not Chains? Q. Hello, Perhaps you can help me with an article I'm writing. I'd like to know what reasons auto makers have for using a timing belt as opposed to a chain. I'm quite the cynic, and my view is that auto makers do it to lower production costs and make it possible to gouge car buyers long after the sale.

To me, a mechanical idiot, by the way, it makes no sense to take a part vital to engine function that almost never breaks, and replace it with one that will. Am I just being cynical, or is there more to the timing belt issue than what I perceive?

I've also heard the argument that it makes an engine quieter. I can't recall ever actually hearing a timing chain to begin with. I think car buyers would put up with a little more noise in exchange for a little extra security. Any help you could give would be appreciated.

Steve

A. You want me to explain why engineers do the things they do? The main reason an engineer changes things is because he can. It doesn't have to make sense to you or me as long as it makes sense to the engineer. Serviceability is not on the engineers list of considerations, neither is cost or upkeep.

Purportedly, the main reasons for using a timing belt instead of a timing chain is less noise and lighter weight. It also costs less than a chain. This is to keep the total cost of the vehicle down. Ever see a vehicle improvement that resulted in the lowering of the vehicle price on the sticker? I haven't. So I can only assume the money saved goes into the manufacturers pockets. Also, the manufacturer doesn't care if you have to spend $500.00 every 60,000 miles to replace it, that's your problem. All they want to do is make more profit.

The lighter weight is to make the vehicle as a whole lighter, thus more fuel efficient. There is no question a belt weighs less than a chain. As for noise, the longer the timing chain is, the more prone it is to making noise. With SOHC and DOHC engines, this does become a bit more of a factor.

If there is more to it then what we are told, I don't know what it is. As someone who has to deal with what engineers design every day, I still haven't figured out why they do the things they do. And to tell you the truth, when I started losing sleep trying to figure it out. I gave up trying.

I have noticed a general trend of the manufacturers going back to timing chains. Nissan comes to mind offhand. All there engines now use timing chains instead of belts. GM also has gone back to timing chains. Ford and Chrysler have also started using timing chains more. So maybe they realized that timing belts aren't such a good idea anymore.

Bottom line is, they say the timing belt is a general improvement over the timing chain. For me, I get paid to replace them. And I replace a lot more timing belts then I do timing chains.