Brainstorming here..........any thoughts?

Hello, I am now 40 years old and over the years have done my share of automotive repair. I have come to the conclusion that the following 2 ideas should be better developed by the foreign & domestic auto engineers and manufacturers.

1. All vehicle engines should be made with a timing chain. Why do auto engineers continue to build engines with a timing belt ? I understand the dealer side of things where the belt will last the entire warranty period and after that the belt will need to be replaced at the owners expense which is costly but profitable for the dealers. In addition the engineers now have on some models the water pump under the timing chain cover. It’s like a double whammy now on these models. Was it that difficult to have the water pump engineered somewhere else on the engine ? It seems like this is a way to keep the dealers or your favorite mechanic continuing to generate income even though this job can be pretty difficult. I always thought by now the auto makers would make all vehicles with timing chains,but they do not. The question is why not ?

2. Why are fuel pumps always in the tank ? Nowadays you hear of high performance fuel pumps mounted externally to the frame. I understand the theory of keeping the fuel pump cool in the tank because of the fuel,but the external fuel pump benefits also by the cooler fuel running through it. Is this another income generator.

I always thought there were ways to make things better. Timing chains will usually last the life of the vehicle and the external fuel pump will be much easier for the mechanic to change if and when it fails . Shouldn’t these ideas make our vehicles a little easier to maintain and a little less wear and tear on our mechanics.

To all mechanics,feedback welcome…any thoughts ?

  1. I don’t mind having the timing belt changed every 90,000 miles and the water pump changed every 180,000 miles. I believe the reduction of weight by using the belt instead of a chain has saved me a lot of fuel over the last 185,000 miles. I also like knowing my water pump won’t leave me stranded anywhere.

  2. Having a fuel pump in the fuel tank hasn’t been an issue for me. It allows the fuel in the tank to keep the pump from overheating. Perhaps this is also a space issue, but like the first item, in the 185,000 miles I have put on my car, it hasn’t been an issue.

I don’t necessarily think your ideas are bad, but these changes would not have improved my ownership experience with my current car, which is now eleven years old.

I keep my cars for a long time. For me, trading a timing belt for a timing chain, and not replacing the water pump before it fails would mean that they might eventually fail while I am on the road. I prefer the added reliability of being able to proactively maintain them before they fail.

On older engine designs, water pumps were accessible and shared a drive belt with other components…and were changed often because that drive belt was routinely over tightened. With today’s engines, the water pump usually goes for ten years before it needs to be replaced.
On the use of timing belts, they are quieter, and, also, last for many years. They are scheduled for replacement as a precaution at about eight years. That makes them NOT frequent maintenance items.
One car maker, Honda, did go back to timing chains (in 2003). The reason may be that a few states passed laws that timing belts, simply by edict, would last the life of the engine (“Thou shall not fail!”).

My preference is always a chain over a belt. In over 40 years of driving and a ton of miles I’ve yet to ever have to replace a timing chain.
As to why they use belts, it’s production costs. Belts and pulleys are easier and cheaper to produce as compared to chains and sprockets.
(Much like the use of aluminum. Saves weight and much easier to machine along with saving a bunch of money on machine tooling; the latter of which is godawful expensive.)

The main reason for placing the pumps in the tank is sound deadening. Fuel injection pumps really turn some high RPMs and while a barely audible whine may not bother some, other people will complain forever if they have to listen to it.

Back in the late 80s while working for a Subaru dealer I had to put up with several very irate customers who were complaining to no end about a barely noticeable fuel pump pulse noise. These were computerized, carbureted vehicles and they used externally mounted diaphragm type fuel pumps that emitted a very faint “tick” sound now and then. Entirely normal and every Subaru did this. Try and tell the car owners that.
One Subaru owner even threatened a lawsuit because he refused to believe it was fuel pump pulse and insisted it was the “computer” doing this.

I don’t have a problem with in-tank pumps as long as they’re accessible without having to drop the tank. SAAB and Mitsubishi are examples of vehicles with in-tank pumps that are readily accessible by simply removing a cover plate.

That’s my feedback anyway.

I agree that all engines should have a chain AND be non-interference.
The “in tank” fuel pumps are OK as long as there is an service access port in the floor over the tank. I think it’s BMW that provide this feature.

I also prefer timing chains to belts. A couple reasons some makers use belts are lower production costs and less weight (and thus, more power). I’m not sure I buy the “chains are noisier” argument. The chains on my '96 S-10 and '94 K1500 Blazer (no longer own it) don’t make any noise at all…both purr so nicely at idle I sometimes can’t tell the engine is even running. If the chain or tensioner have issues then yeah, it’ll make some noise. Otherwise, I don’t think they’re noisy at all.

I’ve never understood the need to have the timing belt drive the water pump, however. I’m a real big fan of having a single serpentine belt power all of your accessories. Easy on, easy off.

I don’t mind in-tank fuel pumps because of the noise-cancelling effect (sometimes they’re plenty audible even so), but I do wish the sending units could be mounted somewhere that didn’t require dropping the tank to access the pump. Truthfully, fuel pumps shouldn’t fail all that often so it’s not really that big a deal, but at the very least provide a removable panel in the floorboard so that the pump can be reached without removing the tank. Seems reasonable to me.

Timing belts are likely cheaper to produce as was said, permit easier and therefore cheaper engine assembly, and are quieter than a timing chain. A timing belt also requires less extensive enclosing than a chain which must be in an oiltight compartment not to mention that the chain requires lubrication provided from the engine’s oil system. A timing belt makes cylinder head removal and replacement easier for a mechanic but I seriously doubt that engine designers make this a main priority. I don’t know why water pumps re sometimes run with the timing belt unless possibly it is useful to shorten the length of a run between two pulleys to minimize deflection or flapping if you know what I mean. I agree that a timing chain is a far better deal unless you can change a belt yourself and it’s my belief that most people either shrug off the aprox. $500 belt replacement cost or else are not made aware of it when they buy a car. I don’t think that gas mileage is a factor as the new Chev Cobalt XFE has a highway mileage number of 37 mpg and it uses a timing chain.

Fuel pumps for current fuel injected engines must put out much higher pressure than old fashioned diaphram pumps mounted on the side of engine blocks must to keep a carburetor filled. It would be possible to make a high pressure pump that was external to the fuel tank but it would necessarily be larger, heavier and therfore more expensive due to needed heat dissipation mostly to air with some heat shed to the gas flowing through it. In tank fuel pumps for us have with one exception, lasted the time that we kept the cars; one of them to 160,000 miles, another to 135,000 miles. Access covers in the trunk bottom and the tank for in tank fuel pumps should be manditory.

Timing belts require fewer parts and less machining. The water pump driven by the belt is the same situation. Less weight too. Fuel pumps work better in the tank where they will be trying to push the fuel rather than vacuum it. All this seems great on paper. The fuel pump could be made to be accessible, the customer gets ignored frequently.

Outside the tank fuel pumps for F.I. cars are both noisy and expensive. Cost also plays into the belt situation.

Chains can certainly have major problems as well.
On overhead cam engines the chain is substantially longer. They form kind of a large “W” rather than a small oval. A chain this long has many links, and if each link stretches just a bit it can add up to quite a bit. A loose chain then slaps against the tensioner, eventually causing them to break off. The broken off piece will ride the chain up and become lodged in the cam sprocket teeth, causing major top end damage. Chains should be checked for stretch as routine maintenance.
The nice thing about an overhead cam chain is they can be changed from the top by being fed through without major disassembly.

The small oval chain on an overhead valve engine however is a very efficient design.

I will only add one comment. The timing belt and associated stuff is a little quieter than a chain, even one in good condition.

I like the timing belt. As far as chains lasting forever, I never had to change one that broke, but when doing other work such as cam replacement I always did the gears and chain. On a Ford I had I removed the oil pan and it was loaded with nylon from the timing chain gears. Nylon made it quiet, but it eventually wears out. I wish all vehicles had an access panel for the fuel pump in the tank. It’s really bad when the pump goes and you got a full tank. A lot of time we just make an access hole. Really easy on pick up trucks because its easy to make a decent looking cover plate when you put it back together.

I think the main reasons for having timing belts on many modern engines are: 1) Reduced noise. 2) Reduced cost. I too would prefer a chain, but since you really don’t have to worry about it for 100K miles, it isn’t that big of a deal to me. I’ve had two vehicles that had V8 engines (one Ford, one Mopar) with timing chains that were worn out before 200,000 miles, so I’d say that timing chains lasting the life of the engine isn’t necessarily true.

Re. fuel pumps being in the tank—I don’t really see a problem there either. How often do you have to change a fuel pump? It might be different if it was a military vehicle or something that needed the pump to be accessible in the field for emergency maintenance. My car has access to the fuel pump through the trunk–and I haven’t had to replace it yet with almost a quarter-million miles on the car.

My pet peeve would be what a pain it is to change headlights on my car—here is something that could have been designed better.

Timing Chain, Water Pump Replacement, Fuel Pump Access, Oil Filter Access . . .

. . . These are just some of the things that I look at and consider when buying a car. I do all the repairs/maintenance. Buyers have choices. Your wish list is similar to mine.

There are cars out there that fit your wish list. My family’s large GM cars have V-6 engines with small, simple oval timing chains, water pumps driven by an accessory belt, and a removable fuel pump/gauge sender access plate in the trunk. They still have the efficiency to provide room, comfort, and safety and 30MPG on the highway!

I have replaced timing belts before and fuel pumps, too. I got tired of replacing timing belts on our small family “fleet”. I now purchase cars with chains.

One of my chysler cars had access to the pump module on the back of the tank instead of the top. That was neat. I installed a new fuel gauge sender in a Bonneville on the driveway in less than half an hour by working through the trunk.

Some people don’t mind replacing timing belts, timing belt/timing chain driven water pumps, dropping fuel tanks to access a fuel pump/fuel gauge, but I’m with you. Some cars are designed with hard to access oil filters, too. It seems silly and sillier that many people have come to accept it. I guess most people don’t look for these features when car shopping and that’s why no priority is given them, but some of us look. Until the engineers make all car with easier maintenance on these items and better access, I’m sticking to the cars that already offer it.


For most people…A timing chain with a NON-Interference engine is probably the best situation.

. Interference engine…I prefer a belt. The belt is then a maintenance item. If a belt breaks the engine is toast…if a chain slips the engine is toast.

. Keep a car over 250k miles then I also prefer a belt. The last two vehicles I’ve owned that had chains and went past the 250k mark…both needed the chain replaced. Replacing a chain is far far far more expensive then replacing a belt…and a lot more complicated. I can change the belt on my Pathfinder in under 4 hours…Last chain I replaced on a 70’s Chevy pickup took me a full day…Lot more involved…more parts…gaskets…messier…

. Fuel Pumps. I haven’t had a problem with any pumps in the tank yet. The old mechanical pumps that ran off a pulley or the cam…I’ve replaced many. One thing I DON’T like with my Toyota…is the filter is part of the internal pump.

Mike In NH, People Are Referred To The Gates Belts Site For Help In Identifying “Interference” Timing Belt Engines.

Do you know of any information source that has compiled information regarding identification of “interference” Timing Chain Engines ?

How does one obtain that information for a particular engine or engines?


At one point I hated the thought of all cars going to fuel injection because they would be “hard to work on.” But after receiving a four year education in the automotive field, I couldn’t be happier with the direction the technology field is going. I’d like to see an increase in quality with some parts, and elimination of interrence engines, but I understand why everything is how it is. It’s all about money and space and fuel economy. I can certainly understand why some folks (like my father in his 70’s) hate fuel injection and wishes everything would go back to carburaters. They are “so easy to work on”. Armed with just a little knowledge and experience, fuel injection is not anything to be frightened of. Neither is fuel pumps inside fuel tanks nor rubber timing belts. Yes sometimes headlights are a pain to change, but like most things on your car, after doing it one time, it becomes much easier the second and third. I’d encourage everyone to try to perform their own maintenance, to a degreee. Some folks might want to keep their “maintenance on their own car” down to a minimum, like checking air and levels, or oil changes, etc. I have heard so many horror stories of shops ripping people off. THe latest story I’ll share, is a co-worker took his brand new ATV to the dealer for his 50 hour check up. He was charged $150 for an oil change, and check up. They look over the machine, check it all out to ensure everything is still tight and safe. A good service writer will convince some folks that it is certainly worth every bit of the $150. I am more of a skeptic. But know why they charge $150 for a 50 hour check up? Because they can. And because people will pay it. I do wish the automotive field spent more time and research on electric cars in past years. We would be much further ahead today if they poured money into it like they just now are. There would be better battery systems and higher power electric motors that use less energy. I believe in 10 years we will have a practical, affordable, electric car that isn’t bare bones that will start populating our streets. Those are my thought.

Mike In NH, People Are Referred To The Gates Belts Site For Help In Identifying “Interference” Timing Belt Engines.

I know…I’ve used that site myself many times.

How does one obtain that information for a particular engine or engines?

Good question…I know of no source. But those engines do exist. The first interference engine that had a chain that I dealt with was a 71 Toyota Corona.

The newer 4.0l Pathfinders use a chain and are interference. If the engine is totally there may NOT be a way of finding out. But if it’s been around a while there are specific sources on the internet about each vehicle that might have that information.

As soon as I found out that the dealership where I bought my motorcycle wanted to charge me $116 for an oil change, I left and never went back…well, not for maintenance anyway.

  1. My understanding about the move to timing belts is that the reliability o rubber components had been improved to the point where it’s “almost” good enough for this job, whereas “back in the day” it would’ve been unworkable.

  2. With the advent of fuel injection, gasoline had to supllied under pressure to the injectors. Since the most “suction” that can be produced is 14.7 psi @ SL, I’d think you’d have to run larger, heavier, more expensive fuel line to wherever the pump is to ensure an adequate supply of fuel.

In-tank pump isn’t really a problem IF access to the tank is provided beneath the passenger’s seat. Although you certainly make a safety argument for putting the pump forward of the firewall…this way, a fuel line leak aft of the firewall would NOT cause high-pressure gasoline to spray everywhere.