Timing Chains and Timing Belts

I’m sure I’m not the only one who has noticed this. Why is it that more often than not foreign cars well will have engines equipped with timing belts and domestic cars tend to have timing chains? I had read that in Japan the laws are as such so it’s encourages older cars to be taken off the road. So perhaps cars over there typically don’t make it to their scheduled timing belt replacements (I may be reading too much into this). That wouldn’t explain why VWs and Volvos tend to have timing belts though.

You would think that with the reputations for great reliability that some of these companies have, that they would go with the timing chain since it requires no maintence to speak off and is less likely to break.

So why do they do it? Is an engine with a timing belt cheaper to produce? Easier to design? or is it desgined that way for mechanic job security? :slight_smile:

I can only say that I can’t keep up with the changes with Toyota either. My early Corolla/Prisms/Novas were chains…then to belts and recently back to chains. RAV is noisier than H…L with chain on warm up…
I thought my 4 Runner had a belt, so I checked the service dept. and they told me it was a chain. It sure looks and “sounds” like a belt under that plastic outside cover…I don’t think they know.
I see your point. Engineering for durability/profit on replacement/or performance is beyond the average (re. me) consumer.
I did read recently where a bicycle is being made with a kevlar belt instead of chain and may actually last. Is their light at the end of this tunnel ?

The manufacturer’s engineers decide whether to use a chain or a belt. I suppose cost, weight, noise, and other factors are taken into account. I’ve noticed that several manufacturers who used belts in the past are switching to chains. Honda and Toyota come to mind.

My current vehicles both have belts, but I will investigate this issue carefully before my next vehicle purchase. I’d prefer a chain in the future, just to save the cost and hassle of replacing the belt.

You are right about Japanese cars being basically retired at age 10. The government requires a large number of items to be replaced, whether they need it or not, making it easy to sell the car for scrap to a foreign country where they drive on the left side of the road. Malaysia, Thailand, New Zealand, Ireland and many other countries import these cars for next to nothing and get another 10 years out of them.

The average Japanese only drives 7000-8000 miles per year, thus the cars gets “scrapped” before the typical major units get replaced. Such a car will often still have its origial alternator, starter, exhaust system, etc. The government stimulates the industry that way, and cars on the road are very safe. It is incredibly wasteful, of course.

In North America and other jurisdictions, timing belts make a car quieter, but at the expense of more maintenance. It’s interesting that Toyota used to put a belt on a car engine and a chain on that same engine when used in a truck, which would travel further in a year and tolerate more noise.

I have only ever owned one car with a belt, a 1977 Dodge Colt (Mitsubishi Lancer). All others, including a Nissan and Toyota have had chains.

In the early '70’s I worked for a company that made the timing chains many cars use, same type of chain is used in some auto transmissions too.

Chains need lubrication, so oil has to be applied to them or the have to dip into the sump at some point. Chains stretch so some method of adjustment, manual or automatic needs to be designed in. Chains need some slack, but too much slack and they vibrate or gyrate as they rotate. A way to control slack needs to be designed in, via a device to apply tension to the chain. While chains last a long time they are small pieces of metal bunched together and held together by “pins”. Over time this stuff does wear. We used to pull the chains with measured pressure to see at what point they’d break. Auto chains are way stronger than the forces usually put on them in actual use, they are designed to last the useful life of the engine. At 200K or 300K perhaps they are getting “tired” and that depends a lot on the lubrication they have or haven’t gotten during their life in the motor. The longer the chain needs to be the more problems inherent to the chain. Motors with overhead cams need longer chains than push rod designs. Chains need bigger sprockets, more clearance around them, tension system, and oil.

Belts need “0” oil. Sprockets that are a bit wider but otherwise not a big or as strong. Very little clearance is required. A less involved tension system. These make a belt much easier to fit on some engines. Where space is limited, and access to oil is complicated a belt works best. That is just the case in many small engines, and likely why more belts on Japanese and European cars. They developed more small engines from scratch and used overhead cams on most of them. If these smaller more efficient motors used chains they’d be a bit bigger, heavier, noisier, and just might not fit into the small spaces available in the engine bay.

In general, timing belts are lighter and more efficient. Since going from a timing chain to a timing belt, I have never had a water pump go bad because I change with water pump with every other timing belt. I am sure there are countless benefits to using a timing chain, but they come at a cost in increased weight and fuel usage.

Personally, I would not let it be the deciding factor of whether or not to buy a particular car. There are more important factors to consider, like driver comfort and overall reliability.

It’s Not A Case Of “Either / Or.”

I made my last decision based on safety, driver comfort, overall reliability, chain instead of belt, economy (of fuel and maintenance/repairs), ease of maintenace / repairs, dealer support, parts availability, and a host of other factors. One can change a water pump whenever one would like like. If I was worried about increased weight, I’d run on the bottom half of my gas tank. I’m not. I don’t.

The next best thing to a chain, is a non-interference, free-wheeling design with a belt. I have one of those in my fleet, too.

It doesn’t have to be either / or.

I don’t think country of origin is a factor, but I do think engine design is.

V-style engines especially with dual cams on each head have a convaluted path to travek for the driveshaft to run the camshafts. Chains have far more mass, which affects them as they go around turns (centrifugal force applies here) and it’s easier to accurately control the twists and turns of a much lighter weight belt than of a much heavier chain. Remember that the idea here is to accurately control valve timing.

In line 4-bangers are pretty easy to link the camshafts up to the crank with, even if they have twin cams. That makes a chain work fine. Manufcaturing cost then becomes the driver.