What diesel engine systems are covered in these diesel mechanic classes?

The course covers diesel engine components, fuel and lubrication systems, cooling, basic electrical circuits, and truck and car air-conditioning systems.

How does a common rail diesel fuel system differ from EUI and HEUI systems?

A common rail system stores high-pressure fuel in a shared rail, allowing more flexible and precise electronic injector control.

What does an accumulator do in a vehicle air-conditioning system?

An accumulator stores refrigerant, separates liquid from vapor before the compressor, and helps protect the compressor from liquid refrigerant.

Free Course Image Diesel Mechanic classes

Free online course Diesel Mechanic classes

Duration of the online course: 4 hours and 10 minutes

4.8

(12)

Build job-ready diesel mechanic skills fast with this free online course—learn engines, fuel systems, cooling, electrics, and AC basics with practice questions.

In this free course, learn about

Diesel Engine and Fuel Systems Fundamentals
Automotive and Equipment Electrical Basics
Vehicle Air Conditioning Fundamentals and Troubleshooting

About the free online course

Step into the world of diesel maintenance with a practical learning path designed to help you understand how modern diesel-powered vehicles and equipment really work. This free online course is ideal if you want to improve your employability in automotive repair, support a current role in fleet or equipment service, or simply gain the confidence to diagnose issues instead of guessing. You will learn the core concepts that technicians rely on every day, with short lessons paired with quick checks for understanding so you can retain what matters on the job.

You will start by building a strong foundation in diesel engine operation, including the purpose of key components and how energy is produced and transferred. From there, you will connect engine basics to the systems that keep a diesel reliable in real conditions: lubrication and cooling. Understanding oil flow, heat management, and the roles of critical parts will help you recognize symptoms early, reduce wear, and prevent avoidable downtime.

Fuel delivery is another major focus, moving from fundamentals to the differences between modern diesel fuel system designs. By learning why different injection approaches exist and what advantages certain systems provide, you gain insight that directly supports troubleshooting, communication with other technicians, and making informed repair decisions. You will also develop essential beginner electrical knowledge for vehicles and equipment, learning how circuits work and how to think logically when chasing faults.

Because many diesel service roles include comfort and auxiliary systems, the course also introduces air conditioning principles and basic troubleshooting. You will learn what the AC system is designed to do, how it accomplishes that task, and what to look for during a visual inspection. By the end, you will have a clearer, system-level understanding of diesel engines and supporting vehicle systems, along with the confidence to keep learning and applying these skills in a workshop, fleet environment, or personal projects.

Course content

Video class: Diesel Engines 101. Class 1. 25m
Exercise: During Rudolf Diesel's time, what was often used as a lubricant before the widespread utilization of petroleum-based products?
Video class: Diesel Fuel Systems 101. Class 1. 39m
Exercise: What is the primary function of a diesel engine's fuel injector?
Video class: Diesel Engines 101. Class 2. 23m
Exercise: What are the primary functions of a cylinder head in a diesel engine?
Video class: Diesel Engines 101. Class 3. 10m
Exercise: Which component of a diesel engine is responsible for absorbing all of the energy and transmitting it to the transmission or implement it's powering?
Video class: How The Oil System In Your Engine Works Explained. Diesel Engines 101 Class 4. 24m
Exercise: Which component in the diesel engine's lubrication system is responsible for pumping oil and creating flow but does not necessarily build pressure?
Video class: Diesel Engines 101. How The Engine Cooling System Operates. 19m
Exercise: Which of the following is NOT a component of a liquid cooling system in a diesel engine as described in the video?
Video class: Diesel Fuel Systems 101 part 2. Common Rail, EUI and HEUI. 24m
Exercise: Which advantage does a common rail fuel system have over mechanical electronic unit injector (EUI) and hydraulic electronic unit injector (HUEI) systems?

Video class: Electrical 101 for cars, trucks and equipment. Beginner electrical, Class 1. 28m
Exercise: What is the purpose of a circuit in an electrical system?

Video class: Air Conditioning Basic Troubleshooting. AC Beginners Course. Truck AC Class Part 3 14m
Exercise: What should you inspect for on the AC components during a visual inspection when troubleshooting an AC system?
Video class: How Truck and Car AC Systems Work. Air Conditioning Principles and Beginners Class. Part 1. 20m
Exercise: What is the primary function of a vehicle's air conditioning system?
Video class: How Truck and Car AC Systems Work. Air Conditioning Principles and Beginners Class. Part 2. 19m
Exercise: What is the primary function of an Accumulator in an AC system?

Learn aboutDiesel Mechanic

Explore free online Diesel Mechanic courses designed to build practical skills in diesel engine repair, diagnostics, maintenance, fuel systems, electrical systems, and troubleshooting. Learn at your own pace, prepare for automotive and heavy-equipment careers, and complete each course with an included certificate to showcase your new skills.