Learn · Diesel Mechanics
Diesel Mechanics
Engines, brakes, electrical systems and the ASE certifications that price your labor.
Learning paths
Just browsing? Start here: Diesel Engine Fundamentals →
Content
Engines 5 lessons
- Diesel Engine Fundamentals
- Fuel Systems: Common Rail and Injectors
- Air Induction and Turbocharging
- Aftertreatment: DPF, SCR, DEF
How DPF, SCR and DEF systems clean diesel exhaust, why regens happen, and what fails when they do not.
- Engine Diagnosis
Chassis 8 lessons
- Air Brake Systems
- Drivetrains: Clutches, Transmissions, Differentials
- Steering and Suspension
- Truck Electrical and Electronic Systems
- Multiplexing and Scan Tool Diagnostics
- Preventive Maintenance and DOT Inspections
PM service intervals and the federal periodic inspection criteria of Part 393 and Appendix A, the skill set behind both the ASE T8 test and annual inspection work.
- Truck HVAC and MVAC Service
Cab heating and air conditioning on medium-heavy trucks: refrigerant circuit fundamentals, recovery rules, and where EPA Section 609 certification becomes mandatory.
- Truck Shop Safety: Rim Wheels and Stored Energy
The hazards that hurt diesel techs most: split-rim and single-piece rim wheel servicing under OSHA 1910.177, and controlling stored hydraulic, air and electrical energy before wrenching.
Career 7 lessons
- ASE T-Series: The Advancement Currency
The eight ASE medium-heavy truck tests (T1 gasoline through T8 preventive maintenance inspection), what each covers, and the hands-on experience requirement that turns a passed test into a certification.
- ASE Master Technician and 5-Year Recertification
Holding current certification in T2 through T8 earns ASE Master Medium-Heavy Truck Technician status (T1 is not required), and every certificate is retested on a five-year cycle.
- EPA 609 for MVAC Work
Anyone servicing motor vehicle air conditioning for payment must be certified under Clean Air Act Section 609 through a program that EPA has approved; how it differs from Section 608 and why the regulation sets no renewal.
- DOT Annual Inspector Certification
What 49 CFR 396.19 actually requires before a technician can perform federal annual inspections: carrier-verified understanding of Part 393 and Appendix A plus a year of qualifying training or experience, with no federal card involved.
- From Wrench to Shop Foreman
- ASE Entry-Level Certification for Students
The school-level ASE medium-heavy truck tests: no work experience required, valid two years, not renewable, and designed as the on-ramp to the professional T series.
- Why Diesel Techs Get a CDL
A CDL is a driver credential, not a wrench credential, but shops need technicians who can legally road-test trucks: the Class A/B split, state testing, and the ELDT rule in force since February 2022.