Auto Service World
Feature   September 1, 2007   by Tom Venetis, Editor

Diesel technology gets cleaner, quieter and more efficient

More car makers have to start offering diesel to consumers if the technology is to gain mainstream acceptance

Diesel engines are nothing new. They have been around since 1893 when the German engineer Rudolf Diesel was granted a patent for the technology. Diesel engines work on the principal that compressing a gas will cause a corresponding increase in temperature. As that temperature increases, it will produce enough heat to cause an ignition of fuel.

It is this simple and elegant principle that diesels draw on to work: a diesel engine draws in air which is then compressed to a high enough pressure that when it comes in contact with the diesel fuel injected into the combustion chamber the diesel fuel will ignite, producing the energy that will drive the pistons and therefore vehicle forward.

Because of how the diesel engine works, the fuel mixture in the combustion chamber explodes and expands very quickly. This has meant an often very noisy and sometimes very messy engine, a perception that still plagues diesel technology to this day.

“The main problem with diesel is that they have this persona of being loud, messy and smelly,” says Atin Bhattacharya, vice-president of sales for Mississauga, Ont.-based ADF Diesel, a division of Group Diesel Fournier. “When diesel technology began to be made available in the 1970s for automobiles, especially during the oil crisis, (car) companies often took regular car engines and simply converted them to diesel. As you can imagine, there were a lot of problems with that.”

Another problem was those older diesel engines relied on glow plugs to help in the ignition of the fuel mixture. The reason is not hard to figure out. In cold weather, like what one gets in Canada, the engine block of a diesel will act as a heat sink. As the engine compresses the air in the combustion chamber, that cold engine block will simply absorb that heat very quickly, sucking it up like a dry sponge in water. The engine, will not be able to start because there is just not enough heat to ignite the fuel mixture. So the way to fix the problem was to use a glow plug that would generate the heat needed for the engine to start.

“Where you got into problems on the diesel side of things, especially with the higher mileage diesel vehicles, was that those glow plugs would wear out and would soon produce hard starting, and so you would have to replace them,” says Roy Cornish, a technician with the Etobicoke, Ont.-based Cochrane Automotive.

Other problems with older diesels was that if the air-fuel mixture was off, either by a problem with the injection pumps or in the timing, the car would produce a rather unpleasant amount of black smoke; and white smoke would indicate that the fuel was not burning properly. Further, the notorious knocking noise that early diesel automobiles were known to make, which could be heard the proverbial mile away, was often caused by one or more of the cylinders not burning the fuel properly or by faulty or clogged fuel filters.

These problems have made many car buyers in North American reluctant to purchase diesel technology. However, technicians and makers of diesel technology suggest that could change with the introduction of cleaner burning diesel fuel and new diesel technologies such as BlueTec and Common Rail Diesel Injection systems.

For example, Robert Bosch has been making Common Rail Diesel Injection systems since 1997 and it transformed the old, smoky and rather ponderous diesel engine into something that is now more fuel efficient and cleaner burning. Common Rail Diesel uses a flexible division of injection, divided into pre-, main and post-injections which allows the diesel engine and injection system to be better calibrated. With the use of computer-controlled injection systems and Piezo-enhanced injector actuators, the Common Rail Diesel technology produces a more accurate and controlled injection of fuel which results in a cleaner burning engine that is substantially quieter.

Mercedes-Benz’s BlueTec engine technology is made to provide consumers with a cleaner-burning diesel engine and one that meets all of today’s tough emissions standards, particularly in the area of carbon monoxide (CO) and hydrocarbons, soot particles and nitrogen oxides. The way it works is diesel oxidation catalysts will reduce the amount of CO and hydrocarbons and a DeNOx catalytic converter will remove oxides of nitrogen. A particulate filter will trap soot particles which will be burned off later and Selective Catalytic Reduction (SCR) catalytic converter will take what remains of the nitrogen oxides and convert them to nitrogen and water.

Delphi Corporation as well has introduced its own Direct Action Diesel Common Rail System which offers a Flexible Injection Waveform Control unit that allows for the direct control of the needle lift in the injection nozzle and provides a more accurate and direct control of the rate of injection of fuel into the combustion chamber.

Ed Schmidt, a service department technician with Mercedes-Benz in Toronto says today’s diesel technology is made to not only be more efficient and cleaner burning, but also easier to maintain.

“The new diesel engines today require less maintenance than the older ones,” he adds. “What you simply have to do is follow the regular maintenance schedule, change the oil and filters and you should be fine. And you have fewer replaceable items than there are in a gasoline engine.”

Cornish adds today’s more advanced diesel technology should make diesel more attractive to car buyers, especially ones that are looking for fuel efficiency and longevity.

But if diesel technology is better than what it was before, and provides improved fuel economy with lower overall maintenance, why is the technology still not popular amongst North American car buyers? In Germany, for instance, some 50 per cent of the automobiles on the road are diesel, and the number is nearly the same in many places across Europe.

Peter Bursztyn, a diesel expert in Barrie, Ont. says the biggest hurdle for diesel acceptance is not the technology, but the manufacturers. A long-time supporter of diesel technology, and someone who exclusively drives diesel cars, he finds the car manufacturers in North America have been slow to put the technology out to consumers. As long as car manufacturers continue to make too few diesel cars available to purchase, diesel technology will continue to only be restricted to the large and light truck part of the market.

Sylvain Gilbert, manager of technical services and literature with Mercedes-Benz in Toronto says with the new diesel technology coming online and which should be rolled out into more makes and models of cars soon, he expects sales will begin to increase.

Print this page


Have your say:

Your email address will not be published. Required fields are marked *