Timing Belt vs Timing Chain


#1

Why do car companies use timing belts combined with the design being an interference engine? That’s just asking for problems.

I don’t know much about the design differences and what makes an interference vs non interference engine.

Are timing chains good just as long as they don’t break? I just don’t know why a company would engineer a highly important internal component to have limited life.


#2

Manufacturing cost. Period. All other reasons given are just hyperbole.
Yes, timing chains are good as long as they don’t break. So are belts.

Some claim chains are noisier. They aren’t. I’ve owned, driven, and worked on countless cars over the last 45 years, with both configurations, and it’s impossible to tell by the sound in the driver’s seat whether an engine has a belt or a chain. Anybody that tells you they can tell whether a car has a belt or a chain just from the sound is, IMHO, full of it.

Settle in and get comfortable, because I expect this to be a long thread.


#3

I’m going to repeat something, in case anybody forgot

It’s FAR more expensive to replace 3 chains, guides, rails, etc. on a typical transverse V6 engine, versus replacing a timing belt, idler, tensioner, etc., on a transverse V6

I agree that the typical modern timing chain will last a very long time

Of course, there have been a few notable exceptions

By the way, I picked the V6, because that is a typical engine on a mid sized family car, or your average famly minivan or suv


#4

well I constantly see threads involving timing belts and their problems and expense and the fact that people don t like to have a very expensive replacement being part of regular maintenance.

chain problems are very rarely mentioned and usually only on very old vehicles.

it took 35 yrs for my timing sprocket to wear out on my 75 ford, the chain was still good as the sprocket would have been had it not been aluminium and had been steel , as the replacement sprocket was. of course a steelsprocket would have worn the chain more, so perhaps the aluminium sprocket was a good design.

timing belts cause problems for the average customer. they don t understand the logic behind them and assume that the mechanic is trying to oversell them and that such an expensive maint. item could not be purposely designed.

designed to fail, unfortunately is a fact of auto manufacture.


#5

Having owned 10 cars with timing chains since 1958!, I’ve only replaced one timing chain and gear set, on a 1984 Chevy small block V8. Not because it broke, buit because it got noisy and would have worn out shortly. Cost was about $250 for a heavy duty set.

Agree, belts are cheaper, and manufacturers claim, quieter.

There are fewer and fewer belts now since the buying public is fed up with their failures and having to replace them periodically. The best maintenance is maintenance that does not need to be done.

Even a relative, a seasoned industry maintenance expert, did not know that the belt on his Hyundai Santa Fe had to be changed regularly, as he had always driven vehicles with timing chains.


#6

“timing belts cause problems for the average customer.”

That is because they refuse to see it as maintenance

If maintenance is neglected, problems will arise, such as bent valves

The same is true of neglected brakes, tires, oil changes, etc.


#7

@Docnick‌

That relative . . . did he read the maintenance schedule for his Hyundai?

Not reading the books that came with a car has gotten many an owner into trouble


#8

So its settled. Belts are stupid. As I suspected. Funny thing is if you were in the market for a new car and wanted some engine specs that were less problematic - like lets say a timing chain, and a normal oil filter (not the element type with a PLASTIC screw on cap over it…ask me why I hate this design…) the sales person would have zero idea as to those specs. The paints shiny isnt that enough?


#9

So far in my short car owning life compared to some of you, I want an engine with a timing chain, metal intake manifold, and regular oil filter. Metal intake manifolds seem to be non existent on modern engines.


#10

@Fender1325‌

“So its settled. Belts are stupid. As I suspected.”

Huh?

What is settled?

I, for one, did NOT agree that belts are stupid

Forgive me for saying this, and I mean no offense . . . but is it possible you had an opinion, and you just wanted the other regulars to also have your opinion?

While it may be the case that most of the other regulars despise timing belts and think they’re stupid . . . I really don’t want to presume anything, though . . . I for one have absolutely no problems with timing belts. I’ve changed a few of them myself. I’ve bought cars, knowing they had timing belts, and I’ve gladly changed them on time, because I recognize it is scheduled maintenance."

I will agree that some people don’t like timing belts

But I will not agree that they’re stupid

Somebody else can agree to that, not me

And like I said earlier, I respect your opinion. But I don’t agree with it


#11

they just think its stupid to have such a major repair/ replacement as part of regular maintenance. it seems like like the manufacturer wants the thing to fail and know that people will neglect them. they want to sell new cars, not make the old ones last.

its also guaranteed work for mechanics. it took the consumers time to catch on. now they know and the belts are going bye byes as the consumers avoid them.

if you don t change your brake pads, you have to get a new rotor, if you don t change the timing belt the engine is shot and most people get rid of the car rather than rebuild the engine.

big difference.


#12

Thank you Wes. @db4690 I was semi joking saying theyre stupid, however, lets agree theyre clearly less than ideal. You seem to justify them because an owners manual gives a time/mileage period in which the belt must be changed.

How about I sell you an engine that has magic composite rings that reduce engine noise, and theyre only good for 105K miles and after that its on you. I’ll write it in the manual that they have to be changed by 105K or else you can damage the engine. The manual says it! My hands are clean.

Where the rest of the engines have rings that can last twice that. Same concept in my mind.


#13

Let’s say this is 1971. Engines are now being designed with the camshaft way up on top of the engine instead of inside the engine block right above the crank where it should be. How are we going to get the cam to turn? Should be use an inexpensive and easy to service timing belt? Or should we use a chain that will have to be 4 times longer than any other timing chain and hope that the metallurgy, plastics, and lubrication of the day are strong enough to make the thing last until the warranty period is up.

It’s technology that now allows us to use chains on OHC engines where we used to need to use belts. Belts are simple. Chains need guides, tensioners, and lubrication to work. And your car may have 1,2,3, or 4 chains.

What’s the difference between an $800 timing belt job at 100,000 miles or a $2500 timing chain job at 150,000 or whenever? The timing belt job is predictable and more affordable.


#14

very few people are fleet mechanics and able to do the replacement themselves.

many people can t afford to pay to have it done, so they just hope the replacement is recommended and not necessary as they have learned that car dealers and makers are less than honest about their products anyway. they are not unwilling to do the belt change, just unable physically or financially or both.


#15

@wesw

“it seems like like the manufacturer wants the thing to fail and know that people will neglect them. they want to sell new cars, not make the old ones last.”

Who is “they”

Think about it for a moment

Let’s say the timing belt on your honda fails, the damage is severe and expensive, and you decide to scrap it and buy another car

Okay, but who’s to say you’re going to buy another Honda?

It can’t be some global conspiracy, involving all of the manufacturers. Because some of them never even used timing belts

Some “gentlemen’s agreement” perhaps?

I like you, you make me smile

I mean it in a good way


#16

The manufacturers did this to themselves. They started making belts using natural rubber as the matrix and natural rubber does not age well. Once the rubber starts to deteriorate, the reinforcing fibers become delaminated and the belt breaks.

Newer belts use a urethane rubber that lasts much longer, but still eventually cracks and allows the fibers to delaminate. If they used a silicone rubber, the belts would last the life of the engine easily.

The belts could also be easier to replace. I had a 79 Dodge Colt with the 1.4 Mitsubishi engine, changing the timing belt was a 20 minute repair. The later Mitsubishi 1.5 engine in my 90 Dodge Colt was much more difficult to change, but no where near as hard as the belt on a Honda.

From the manufacturers viewpoint, in the late 70’s when timing belts started to be used, most new car buyers only kept their car 4 years, and the timing belt lasted 4 years so the manufacturers customer, the one they made money off of was not affected by the cheaper belt.

As people started keeping their cars longer, the manufacturers had to make the belts last longer so they upgraded the materials. Some also got their dealerships to offer a special price on the timing belt package as Honda did so it didn’t seem so bad to those customers that kept their cars past the belt life,

Now, new car buyers are keeping their cars an average of 11 years. This may drop in the next survey but the recession was the reason that people were holding on to their cars longer. They could have gone to silicone rubber belts but those are really expensive. If the chain will last through the 11 years and costs less than a belt, then that is what they are going to do.

The chains used on an OHC engine are not the heavy duty, multi row toothed chains used on the old iron block V8’s of yore. They are more like bicycle or motor cycle chains. Some are double row and will last forever it seems like, but more and more, they are going to lighter duty single row chains. We shall see how these hold up.


#17

I’m still with Wes on this. “They” is the car manufacturers. It’s not in their best interest to make a car that just keeps going and going and going. I find a lot of times not only does something not last as long as it should, but the replacement is difficult. They engineer under the confines of saving cost down to the penny, and among a team of engineers assigned to different components. Sometimes it seems like fitting each teams design under the hood to be cohesive, and accessible for standard maintenance to be an afterthought.


#18

What’s lost here is the fact that cars and their engines last a whole lot longer today than ever before. Complaining about a pretty big dollar maintenance obligation at nearly 100,000 miles is kind of silly. In my driving lifetime cars needed valve jobs, ring jobs, and major overhauls well before 100,000 miles. I guess it’s reasonable to hope for an eternal life for your car, but it’s completely unrealistic. Sure, getting the belt replaced is a big bite, and so is replacing a steering rack or ball joints, but transportation just does cost a lot and everyone wants the most for the least. You can avoid all this by getting a new car every 4 or 5 years, but if you want to spend less and conserve resources you fix what you have.


#19

@keith apparently the timing chain on the new hemi’s from dodge look like a bicycle chain.

All of this begs the question, why was the camshaft moved over the head causing the need for all of this re-engineering?

My 1950 Cadillac has a basic short chain up front and normal cam in the block. Apparently this tank got in the low 20’s highway mpg. In 1950. This could lead off into a whole other tangent, but really what it comes down to in my mind - is cost. Mileages reached the 40’s in the early 90’s. Somehow we haven’t made progress? I dont buy it.

I will say cars last longer today in general and thats great. Theres just aspects like timing belts where I plain do not see an advantage.

I’ve heard of manufactures changing a design because it saved something like $1.00 per car. Which would add up a lot right? Why not pass that $1.00 over to the buyer and sell a car thats built right? It bothers me.

It almost seems like the most effective method to car ownership is to find a model you like, with a good engine design, and keep it. Rebuild it and keep going.


#20

Cars are designed for the assembly line, not for ease of repair. Things that are awkward when repairing and very easy to work with on the assembly line. Saving assembly time results in being able to offer the vehicle at a lower cost, and with the reliability of todays vehicles, it is a good trade off for the customer as well. The customer being the new car buyer, not those who buy the car second hand.