In our article about the most reliable motors, modern motors are almost never found. Moreover, among those who are better not to take, the new majority. Coincidence? I don’t think so.
It would seem that with the development of technology, motors should become more reliable and more reliable, but for some reason this does not happen. It seems that we are observing the opposite trend.
Yes, according to many garage "specialists", the grass was greener before, but in this particular case, alas, they are right … There are many reasons for this, and the effect of these reasons is taking shape, often giving rise to another "owner's grief". Let's try to consider the possible negative factors in more detail, which is why the motors began to break more often.
The first problem. Technical complication
Probably, the root of all troubles is the tightening requirements for fuel consumption and environmental friendliness of engines in the absence of new ideas and designs. In fact, all the "innovations" that we see are compressors, turbocharging, direct injection, variable timing and multi-valve designs. All this, in fact, appeared back in the fifties and sixties, and most of the technologies began to develop back in the twenties and thirties (how not to recall the supercharged Mercedes-Benz 770K of the early 30s loved by the top of the Third Reich).
The great driving force behind the progress of piston engines in the first half of the 20th century was aviation, which greatly accelerated the work on injection, all types of pressurization and multi-valve structures. On the ground, these technologies were used much less widely: in racing motors and on individual especially progressive cars, but their mass use became possible only with the advent of cheap and reliable electronics in the early 90s.
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At the same time, car manufacturers were legally obliged to maintain a certain rate of reduction in fuel consumption and began to tighten standards for the emission of harmful substances. At first, the introduction of unconditionally progressive technologies was enough. Multi-valve cylinder heads quickly supplanted two-valve designs, primarily because even without a catalyst, the exhaust of such an engine was cleaner.
Of course, the number of parts in the timing mechanism and the complexity of its maintenance immediately increased. But progress in metalworking made it possible to complicate the motor with almost no loss. The transition to electronic fuel injection and integrated engine management systems, which made it possible to bring together the control of injection, ignition, transmission, and engine service procedures, was also, of course, a breakthrough. It has significantly improved engine performance and increased reliability.
Although many remember the mistrust that was bestowed on the first injection machines and the advice of experienced "garages" who warned about how difficult it is to repair such systems (or a simple carburetor!). History has put everything in its place: the injection systems turned out to be more reliable than the old power systems, although it really became much more difficult to repair complex equipment on the knee.
The next technology that was massively implemented on all internal combustion engines is the timing system: VANOS for BMW, VVT-i for Toyota, i-VTEC for Honda, etc. Roughly speaking, it made it possible to shift the opening and closing times of the intake and exhaust valves, depending on the engine speed, in order to provide good traction at both low and high speeds. In other words, it made it possible to improve the power characteristics of motors without compromising efficiency.
In fact, the design is not very difficult to implement, it turned out to be too new, and for many manufacturers it was not at all problem-free: new wear parts appeared and a new headache for the owners of such machines. For example, knocking on a cold one, breakdowns and system failures.
Then there was the massive introduction of turbocharging. It allowed to use a "loophole" in the European and Japanese driving cycles for measuring fuel consumption and to reduce the passport fuel consumption, while at the same time greatly improving the dynamic parameters of cars. Of course, turbocharged cars are much more difficult to operate than naturally aspirated cars, they are afraid of even minor disruptions in the operation of all systems.
The latest technology that is gradually being introduced en masse is direct fuel injection. It significantly increases the capabilities of the engine, but also requires the use of complex components with a limited resource and very vulnerable due to the precise design and harsh operating conditions. And, in addition to increasing the likelihood of failure, it also increases the cost of repair.
But the application of these old technologies in general was not a problem, in many ways they were worked out long before the mass introduction on racing motors. During the transition to mass production, there were mistakes with miscalculations, but in general these are progressive technologies. They just had to be implemented too quickly and too massively to fit into the legal framework. Only the growth rates of efficiency did not keep pace with the tightening of requirements.
The second problem. Reduced friction losses
Soon there were signs of overcomplication like throttleless intake systems and obvious attempts to reduce internal friction - in fact, by reducing the reliability of the nodes. Less friction means more efficiency, but at what cost? First of all, many of the plain bearings in the motor were simply reduced in size. The sizes of crankshaft journals, piston pins, balancer shaft liners, camshafts and chain links have decreased …
Of course, metallurgists produced new alloys, and parts became stronger. Only not everywhere and not in everything. Motors have become much worse for overloading. To further reduce bearing frictional losses and lubrication energy costs, increasingly thinner oils were used and the oil pressure in the system decreased.
Unfortunately, miracles do not happen: a thinner oil has a film less resistant to loads, and a controlled oil pump is not only more complicated, it also does not provide a pressure reserve at the most common engine operating modes.
The third problem. Increase in operating temperature
In addition, to increase environmental friendliness and economy at low load, they tried to increase the operating temperature of the engine. And in order not to lose power, they introduced controlled thermostats, which allowed the engine to cool slightly under load. But the increase in temperatures had the most negative impact on the rate of oil wear, aging of plastic and rubber engine parts … In general, the hassle was added.
In addition, a controlled thermostat cannot instantly reduce the temperature of the motor, and often the temperature under load is also higher than optimal, which causes detonation and accelerated wear. And yes, they began to change the oil less often, but a breakthrough in the technologies of its production did not happen either, however, this was the topic of two separate articles.
The fourth problem. Relief of the piston group
The rest of the reasons for the decrease in reliability, which we describe below, are somehow related to the main factor. But at the same time, they could develop without taking it into account. The transfer of control over the combustion process to electronics with feedback made it possible to significantly lighten the piston group and many other parts of the engine by eliminating the "safety margin" that was required in case of any failures in the operation of simpler control systems. Unfortunately, electronics are impermanent and do not always correctly diagnose errors in their work. And the stock of "hardware" in terms of reliability has already become less, and a slight deviation of parameters from the norm can already lead to the failure of parts.
Do you know how much power the 1.8-liter VW Golf from 1984 produced? 90 with carburetor, 105-115 with injection on the GTI. Quite "vegetable" parameters by today's standards. Motors 1.8 EA888 series now have a power of 182 forces, and the increase in torque is even two-fold. The introduction of all new technologies has made it possible to create motors with a degree of boost that exceeds the parameters of the racing ICEs of thirty years ago. And any increase in load and temperature entails accelerated aging of metals and a decrease in the resource as a whole.
The fifth problem. Lack of time for full motor tests
If the "safety margin" was at the nodes, then it was chosen almost to the end. The sharp acceleration in the growth of requirements forced automakers, especially among the leaders of the premium segment, to abandon the practice of gradually innovating in old engines and gradually improving design. Engine series are now frequently changed twice in the short life of a model in production. Of course, both the testing time and the number of tests carried out with new motors are reduced.
Most of the tests are performed on computers, and software, as you all know, often has bugs. As a result, clearly unfinished designs are published, the problems of which are corrected already "in the process". So five or six routine replacements of injector types and materials of liners, piston rings and piston groups is just a payment for the fact that the motor of your car is the most "progressive".
The sixth problem. Rarer maintenance and diagnostic complexity
If you try to look under the hood of a modern car, and then under the hood of a "youngtimer" from the nineties, it will be clearly noticeable how much more compact the motors have become and how much more tightly they have begun to fit into the engine compartment. Nobody wants to carry air, and the requirements for the growth of the internal space while maintaining the external compactness of the machine only increased over time.
Sometimes this is accompanied by a clear overcomplication of units or deterioration of their working conditions. But in any case, it entails an increase in the complexity and time spent on diagnostics. The service has to rely more on electronic self-diagnostic systems and less on visual control and the connection of additional control devices. In addition, service procedures have become less frequent, which means that there are fewer opportunities to identify problems at an early stage.
The seventh problem. Unfavorable working conditions
And the last factor is probably the increase in the average engine load. New automatic transmissions are designed to reduce fuel consumption, which means they force the engine to operate at maximum load at a given speed. All this saves fuel, but is not always harmless to the units. The new automatic transmissions make it easy and carefree to use all the engine power, and the reduced noise levels of the units make the process pleasant and easy. Payback, as always, with reliability.
What's the bottom line?
Each of the reasons separately does not make the weather, but in total they create a feeling of constant problems with the motors in many new cars. The more conservative producers have fewer, the most progressive have more. In fact, the number of failures during the warranty period is generally reduced, and this is a consequence of the quality control systems. Now auto companies have the opportunity to control the resource, not to lay an excessive safety margin if the number of warranty problems does not exceed a reasonable level, and to correct the errors of problematic series of motors in time or remove them from production if it is impossible to correct the situation with small forces.
Unfortunately, everything that is outside the warranty period "and a little more" is already outside the interests of the concerns. It may turn out that after the warranty the car will not travel long and the repair will be very expensive, large-block and with the involvement of a special tool. In the meantime, the buyer can enjoy the new car - it's still faster and more economical. Moreover, the difference in the cost of the fuel saved can often even exceed the increased expenses for engine repairs in the future.
Author: Boris Ignashin
