The mechanic may have to test drive the vehicle or use testing equipment, such as engine analyzers, spark plug testers, or compression gauges, to locate the problem. Once the cause of the problem if found, mechanics make adjustments or repairs. If a part is damaged or worn beyond repair, or cannot be fixed at a reasonable cost, they replace it, usually after consultation with the vehicle owner. To prevent breakdowns, during routine service mechanics check parts and adjust, repair, or replace them before they go bad. They usually follow a checklist to be sure they examine all important parts, such as belts, hoses, steering systems, spark plugs, brake and fuel systems, wheel bearings, and other potentially troublesome items.
Mechanics use a variety of tools in their work.
Automotive and motorcycle mechanics in larger shops increasingly specialize. For example, automatic transmission mechanics work on gear trains, couplings, hydraulic pumps, and other parts of automatic transmissions. Because these are complex mechanisms, their repair requires considerable experience and training, including a knowledge of hydraulics. Tune-up mechanics adjust the ignition timing and valves, and adjust or replace spark plugs and other parts to ensure efficient engine performance. They often use electronic test equipment to help them adjust and locate malfunctions in fuel, ignition, and emissions control systems.