Wimpy Timing Belts by Design

Your Point About The Water Pump Brings Up Another Discussion.

Should a water pump fail on a car with the pump driven by a belt or a chain, it leads to fairly expensive water pump replacement.

Also, on some timing belt cars that develop a weeping water pump, the minor coolant leak can soften a timing belt and its teeth and cause a break down and even engine damage (interference engine).

Maybe manufacturers should design engines (especially ones with chains) to always run the pumps from an accessory belt, but then . . .

. . . Many people would ignore maintaining their accessory belts the same way they ignore timing belts, have the belt break or become loose and drive with no water pump in operation and cook their engine.

CSA

Interesting that Toyota has gone, in the models I’ve had , from chains, to belts and back to chains. And, it doesn’t affect their prices. The deciding factor seems to have been quietness as the recent ones with chains are just as quiet as the previous belts…exception on cold weather starts. Quiet cars, a reason for belts, is just as important a factor as longevity. When someone buys a car, the clanging of a chain, regardless of it’s better reliability, will turn the customer off.

As far as engineering cars to be non interference, we have to remember the number one goal of all car companies is to make a profit. For we more informed, it would mean making the engines as you say. But companies don’t make as much money off us…they make more off the less informed, less interested, “yes, just replace the motor or buy a new car” crowd.

A replaceable belt is a way of telling a customer; " your motor is trash, but it’s your fault because you didn’t follow the expensive maintenance intervals on our other wise, ultra reliable car." WE all pay to play when it comes to cars, one way or another. Corporate bean counting…and the weak link timing belt is an example of it.

But then, nobody would buy these cars and rubber timing belts would be GONE in a year…

I would. I value a quiet car. Timing chains tend to be noisier.

I might add that I have seen a trend towards longer lasting belts. Some replacement belts come with a longer life recommendation.

Considering the cost per mile of a timing belt, I would tend to prefer them.

Back in the day most cars engines were non-interference. The pistons were designed with cut outs on top to allow for valve clearance. Unfortunately these cut outs on top of the piston caused slightly higher emissions, and thus were eliminated do to stricter emission regulations.

Joseph, I Think You Meant To Say That Timing Chains Tend To Be Noisier.

Anyhow, in the case of my Pontiac (one short chain), noise is not an issue. The car is extremely quiet inside and even standing in front of the car while running.

Your comments about belts with a longer life brings up another discussion. With all the modern materials we have available now, one would think a resonable cost timing belt could be developed that has the longevity of a chain, virtually the useful life of the car.

I notice that some cars have long timing belts that snake all over just as some cars have long snaking chains. Other cars have shorter less convoluted chains or belts.

I’m not sure that running a belt or chain in a simple, short circuit helps with the longevity or not, but some cars use 3 or 4 shorter chains in place of one really long one.

Some have suggested this is a cost issue. If cost determines whether or not a car has a belt or a chain then why do “cheap” Dodges have DOHC V-6s with 3 timing chains (These are very smooth running and quiet engines, by the way.) ?

CSA

My point actually about any price differential is that the manufacturing costs are so low one would never notice the difference.
Car makers contract for this stuff in droves and get it on the cheap, belt or chain, and any additional costs would be buried in the price and never known. It’s not like you would see the price of the go up a few hundred bucks because it now has a chain instead of a belt.

An example I found by accident one time was with a Subaru DOJ, or double offset joint which is the inner joint on the halfshaft.
The dealer cost on this joint was 65 dollars with customer retail being about 98.
It was discovered that the approximate real cost of this joint was about 6 bucks.
If a DOJ can be manufactured and shipped for what is essentially pocket change a timing chain can be done for the same.

I have learned through reading these boards that automakers seem to build a lot of what I consider “dirty tricks” into vehicles, besides just timing belts. What about $400 for a spare car key which you used to could get for $1.99 at any hardware store, 'cause it has a ‘chip’ in the FOB? What about vehicles which require removal of a wheel to change the battery, or removal of the bumper to change a headlight?

I even read somewhere where Toyota was selling minivans that don’t even come with a spare tire! That one really stuck in my mind, because if I were shopping for a new vehicle, it would never even cross my mind to ask whether the vehicle included a spare tire! I thought that was part of a new car.

I think that’s what happens with all of these issues, people are dazzled by that shiny new car, and don’t think to ask about these things until long after the transaction is completed. Several wiser people than me have posted on various threads that car buying is much more of an emotional decision rather than a rational one.

Maybe we would all be well advised to follow the Tom Magliozzi school of thought: buy the cheapest wreck possible and drive it until it falls apart.

Neither timing chains or timing belts are ideal, each has good and bad points. The timing chain does last longer, but not forever and isn’t infallible. A chain stretches over time and the slack needs to be taken up. The slack causes the timing to shift a bit and when it goes beyond the ability of the slack take up system the chain can break or slap around in there and get noisey. Timing chain is heavier, and generates more noise and vibration in normal applications. The chain and sprockets also take up more space which can limit engine design. A chain must be lubricated so oil must be available to the chain and built into the design, adding to the potential for oil leaks. Chains also don’t handle higher rpm’s as well as belts.

Timing belts have lots of advantages but the biggest disadvantage is they deteriorate over time and need to be replaced as a maintenance item. A timing chain is maintenance free but when a chain goes bad the repair is expensive.

I just accept the cost of the timing belt replacement as a cost of maintaining the vehicle. A warning light at the mileage and/or time interval isn’t beyond the technology of the day and should be considered by mfg’rs using timing belts.

Interference engines are that way by design. To make engines run cleaner and get more efficient power (therefore better mpg) they use variable valves and other designs that result in some engines being interference type motors. If you could get the same performance without risking the valves whacking into the pistons if the valves stop operating I think mfg’rs would use the non-interference design. Interference engines are part of the picture if we want the most efficiency from our motor designs.

Why buy a car with a 60K or similarly short change interval? That is up to the buyer, but perhaps there should be a notation on the window sticker (like EPA mpg ratings) that indentifies a motor with a timing belt, the change interval, and the approximate cost of a timing belt job. Currently most owners buy new cars without a clue about timing belts or chains in the motor. It is the buyer(s) of used cars that really need to dig deeper into timing belts or chains since the used car is likely going to need a new belt rather quickly when purchased used. So it is buyer beware, or buyer be aware and the information isn’t presented “upfront” so it takes digging into the owner’s manual (when one exists) for the info.

Back in the day most cars engines were non-interference. The pistons were designed with cut outs on top to allow for valve clearance. Unfortunately these cut outs on top of the piston caused slightly higher emissions, and thus were eliminated do to stricter emission regulations.

I was wondering about that. When I rebuilt my Vega engine I got new pistons from IECO with pistons that gave me 11:1 compression ratio. The pistons stuck out above the top of the cylinder but had indentations at the top of the piston for valve clearance.

What you’re saying makes sense.

But then, nobody would buy these cars and rubber timing belts would be GONE in a year.

This is so typical. Timing belts aren’t made of rubber, but that isn’t the only thing that makes that statement patently false. You are living with the false assumption that a vehicle with a timing chain is inherently better. It isn’t, but even if it were, some car companies don’t redesign their cars every year. If your assumption that everyone thinks and believes the same things you do were correct, it might take up to three years before the next generation of certain models arrive in the showroom.

As a car owner, I don’t mind giving my car a little TLC when it comes to replacing belts and hoses BEFORE they fail. The same goes for the water pump. Spending that 1/2 of a cent per mile gives me peace of mind you can’t get when you have a timing chain and wait for your belts, hoses, and water pump to fail before replacing them.

…perhaps there should be a notation on the window sticker (like EPA mpg ratings) that indentifies a motor with a timing belt, the change interval, and the approximate cost of a timing belt job.

Why stop there? Why not include the cost of high performance tires (on cars so equipped), oil changes, automatic transmission service, and everything else important for cost of ownership?

Whitey, All That Might Be Too Much Information, But I Do Like Your Suggestion About Indicating That A Car Has More Than High Average Cost Tires Or Low - Rolling Resistance Tires That Wear Very Fast.

Most of all though the “timing belt time bomb” should be made known to consumers while they comparison shop, not after purchase and I agree that maybe we shouldn’t stop there, but those timing belts destroy engines, either by neglect or weepy water pumps, etcetera. They give no warning, auditory or visual, the rubber just snaps.

CSA

It’s called crevice volume and the drive to minimize it has affected not only valve reliefs in the piston top but the spark plug stick out/well depth and the top ring proximity to the piston dome as two examples. Seems like a small thing but when you multiply it times the number of combustion strokes * cylinders * vehicles, it becomes something of significance. Especially when the boulders and stones have already been addressed and we get down to the level of sand, metaphorically speaking…

Even if I my water pump was driven by an accessory belt, I think changing it prophylactically every 180,000 miles before it fails is the best option for making an engine last. It’s too bad we don’t have statistics on whether or not changing the water pump prophylactically reduces catastrophic engine failure.

If a car were built with low maintenance and longevity as the foremost issues it would sit unsold on the back row of the dealership. Glitz and image sells cars, even the hybrids.

But then, nobody would buy these cars and rubber timing belts would be GONE in a year.

FOR THE RECORD…The material timing belts are made of is pound for pound 5 times STRONGER then steel.

The VAST majority of car owners sell their cars LONG before it reaches 250k miles…Obviously Caddyman is one of them. If he weren’t he’d be complaining about how much
a new timing chain costs. They are far more expensive then a timing belt.

How true,why not produce the engine so you can acess the timing belt easily?-Kevin

I changed many a timing belt on Fiats, working “The Line”. If my memory serves me correctly, we changed out the belts every 25,ooo miles. Look on the bright side!

This is an interesting point. When I had to replace a water pump, it was easy to diagnose because I heard the noise and I was able to put a long screwdriver on the pump and pin down the noise, and I was able to see that water had been leaking from the weephole. If it had been under the timing cover the diagnosis and repair would have been more difficult. Perhaps a minor concern overall, but it made life easier for me that day.

Also, A Pump Run By Accessory Belt Instead Of Timing Belt Is Generally Much Easier And Cheaper To Replace And That Makes It More Practical To Just Replace It As A Preventive Measure.

CSA