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What does a Diesel Mechanic do?

By D. Jeffress
Updated Mar 02, 2024
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A diesel mechanic performs preventative maintenance and repairs on diesel engines and vehicles. He or she might specialize by working with large trucks and buses, passenger vehicles, or heavy machinery such as bulldozers, cranes, and tractors. Diesel mechanics are valued for their expert knowledge of brake systems, transmissions, and electronic components unique to diesel powered vehicles.

Diesel mechanics are often required to perform routine maintenance checks on vehicles and machinery. They may follow an inspection checklist or rely on their previous experience to ensure everything is in proper working order. If serious problems are found during a maintenance inspection, mechanics typically make notes and schedule necessary repairs.

When repair work is needed, a diesel mechanic will carefully assess the problem and acquire any necessary replacement parts. Depending on the nature of a repair job, he or she may use pneumatic tools, welding and cutting equipment, and various hand-held wrenches and screwdrivers. Once repairs are completed, the mechanic starts the engine to make sure it runs properly.

Most modern diesel engines are equipped with several electronic components and computer processors. Therefore, it is very beneficial for a diesel mechanic to be proficient with computers and have a strong understanding of electronics. They often use diagnostic machines and computer software to ensure all electronic parts are working correctly.

To become a diesel mechanic, a person is usually required to be at least 18 years of age and possess a high school diploma or GED. Continuing education is not typically required, though many community colleges and vocational schools offer diesel engine repair programs. Such programs, which take from six months to two years to complete, provide students with hands-on and classroom training. Some schools even offer job placement services to help beginning mechanics to find work.

While no specific license or certification is required to work as a diesel mechanic, many new workers choose to obtain special credentials offered by a nationally recognized organization, such as the National Institute for Automotive Service Excellence (ASE) in the United States. A mechanic with at least two years of experience can become certified by passing an ASE test. With certification, a mechanic becomes a more desirable prospect to potential employers and customers.

A majority of diesel mechanics are employed by the truck transportation and manufacturing industry, performing regular maintenance on large trucks, buses, and heavy equipment. Some work for specific construction and manufacturing corporations, where they maintain and repair company vehicles and machinery. Other diesel mechanics are employed in independent shops that service passenger vehicles.

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Discussion Comments
By kentuckycat — On Aug 08, 2011

@JimmyT - I believe diesel mechanics generally make more than regular automotive mechanics. I figure this is a result of diesel vehicles being larger and more complicated. Plus, there are fewer diesel vehicles, so prices are probably higher.

I would guess that a regular mechanic starts off making around $30,000 a year, and a diesel mechanic maybe $35K. I have known some older mechanics who make upwards of $60,000. All of this depends on location and the size of the business, of course.

Like any other business, a mechanic who owns his own shop also has the potential to make much more money if they are able to be successful. Of course, the business could fail and the person could lose a lot of money, as well.

By JimmyT — On Aug 08, 2011

I'm not familiar with diesel mechanics, but I'm pretty sure the ASE certification for regular mechanics is broken down into several different areas like transmission, brakes, suspension, and so on. I think if you pass all of the tests or at least a certain number, you are considered a "master technician". Does the same system apply to diesel mechanics, or is there simply one test that covers everything?

Also, out of curiosity, how much do typical mechanics make? How does a diesel mechanic compare to a regular mechanic? What if they are ASE certified?

By jcraig — On Aug 07, 2011

@matthewc23 - That is interesting to know. It is a shame that our economy is in bad shape, because I'm sure quite a few talented mechanics have to be turned away because they don't have the qualifications of other workers.

At the same time, it could be hard for beginning mechanics to find two years worth of work so that they can qualify to take the ASE tests. It sounds like your friend works at a higher profile business, though, where rookies probably wouldn't fare well to begin with.

I am curious, though, how successful are the college placement programs? What kinds of jobs might a beginning diesel mechanic be able to find? Do they usually work at smaller shops and then work their way up to larger transportation companies?

By matthewc23 — On Aug 06, 2011

I have a good friend who works as a diesel mechanic. Like the article mentions, it is only necessary to have a GED to be considered for a job, but having better qualifications is almost required given the current economic situation.

My friend works at a fairly large garage that is responsible for repairing semis and buses. He is also party responsible for hiring new mechanics. Any time a job is listed, several dozen people apply, and usually those that are ASE certified automatically make it to the last round of selection. At the very least the person has to have completed a technical program.

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