A professional who repairs and maintains diesel engines used to power machines, such as buses, ships, trucks, railroad trains, electric generators, and construction machinery, using handtools, precision measuring instruments, and machine tools. Respnsibilities include:

• Diagnoses trouble, disassembles engines, and examines parts for defects and excessive wear.
• Reconditions and replaces parts, such as pistons, bearings, gears, valves, and bushings, using engine lathes, boring machines, handtools, and precision measuring instruments.
• May weld and cut parts, using arc-welding and flame cutting equipment.
• May be designated according to type of diesel engine or equipment repaired as automobile diesel-engine mechanic; bus diesel-engine mechanic; marine diesel-engine mechanic; truck diesel-engine mechanic; construction diesel-mechanic; farm diesel-mechanic; diesel locomotive repairer.