Automotive Mechanics Honor

Vocational Activities

Requirements

1. Demonstrate the ability to start a car. Explain why it is necessary to periodically check the oil, water, fuel, tires, brakes and battery.

   Answer: Each item affects safety and operation. Oil lubricates the engine (without it, the engine seizes). Radiator water cools (without it, overheating). Fuel is energy (without it, it stops). Tires ensure grip (inflation and wear). Brakes are safety (a leak or wear = accident). The battery keeps the electrical system working. — Preventive maintenance prevents breakdowns and accidents. Oil: change every 10,000 km or as per the manual. Radiator water with additive. Fuel: never let the tank run on reserve. Tires: inflate monthly, check wear. Brakes: pads, fluid. Battery: clean terminals, age (3-5 years). A driver's license (CNH) is mandatory; the ANTT regulates. Adventism: care for life and property reflects Christian stewardship.

2. Properly change a tire and demonstrate how to repair a puncture in it.

   Answer: You park in a flat location, chock the wheels, position the jack at the correct point, raise the car, remove the bolts with a lug wrench, swap in the spare, lower the car and tighten the bolts in a crosswise pattern. Punctures: a repair kit with a plug cord and glue. — Tire changing follows the DENATRAN standards of the Brazilian Traffic Code (CTB) for Brazilian drivers, being essential in emergencies. Plug-cord type repair kits are sold at gas stations for R$15-30 and seal small punctures without the need to remove the tire from the wheel nowadays.

3. Explain the principle of 4-stroke and 2-stroke engines and the difference between gasoline, diesel and ethanol engines. Explain the main differences between the carburetor system and the electronic fuel injection system.

   Answer: 1) Principle of 4-stroke and 2-stroke engines: The 4-stroke engine completes the cycle in 4 movements of the piston — intake (the air/fuel mixture enters), compression (the mixture is compressed), explosion/combustion (the spark plug ignites and pushes the piston, generating force) and exhaust (the burned gases leave). This is the Otto cycle. The 2-stroke engine does the same work in just 2 movements of the piston (intake/compression in one and combustion/exhaust in the other), being simpler and lighter, but less economical and more polluting. 2) Difference between gasoline, diesel and ethanol engines: In the gasoline engine the ignition is by spark (spark plug). In the diesel there is no spark plug: the ignition is by compression (the highly compressed air heats up and ignites the injected diesel), generating more torque. The ethanol engine works like the gasoline one (spark ignition), but uses a renewable fuel made from sugarcane, which is cleaner; flex-fuel cars accept ethanol and/or gasoline. 3) Carburetor vs. electronic injection: The carburetor is a mechanical system that mixes air and fuel by suction, without precise control, requiring manual adjustments and consuming more. Electronic injection uses sensors and a central unit (ECU) that meters the fuel through injector nozzles at the exact moment, resulting in a more precise mixture, lower consumption, less pollution and better performance. — The 4-stroke engine was invented by Nikolaus Otto in 1876, still the standard in automobiles. Electronic injection replaced carburetors in Brazil compulsorily from 1996 for environmental and automotive energy efficiency reasons.

4. Describe the construction of a gasoline engine and briefly explain the functions of the following parts:
   • Engine crankshaft, connecting rods, pistons, shaft, valves, oil pump, carburetor, fuel injector, ignition distributor, fuel distributor, electrical system, including alternator, battery, and regulator.
   • Difference between manual and automatic transmission and how engine torque is transmitted in each case.
   • Difference between front-wheel-drive and rear-wheel-drive cars.
   • Difference between disc brakes, ABS, parking brake, and hydraulic brakes.

   Answer: A gasoline engine is built from a block (with the cylinders), the cylinder head (which closes the cylinders and houses the valves) and the crankcase (oil reservoir at the base). Functions of the main parts: 1) Crankshaft: transforms the up-and-down motion of the pistons into rotary motion, which is transmitted to the wheels. 2) Connecting rods: rods that link the pistons to the crankshaft, transmitting the force. 3) Pistons: move inside the cylinders, compressing the mixture and receiving the force of the explosion. 4) Valves (intake and exhaust): open and close at the right time to let the air/fuel mixture in and the burned gases out. 5) Carburetor or injector: prepares/meters the mixture of air and fuel sent to the engine (the carburetor is mechanical; injection is electronic). 6) Battery and alternator: the battery supplies energy for starting and the alternator recharges the battery and powers the electrical system while the engine is running. (Also included are: spark plugs, which produce the spark, and the camshaft, which actuates the valves at the correct time.) — The modern engine has more than 200 moving parts synchronized in milliseconds, with automotive engineering being an area of continuous research for energy efficiency and the reduction of polluting emissions throughout the automotive world currently in use.

5. Perform the following automotive maintenance services:
   • Check the engine and transmission oil level.
   • Check water. Change the air conditioning fluid.
   • Change the engine oil and oil filter.
   • Change a tire/wheel assembly, following proper safety measures.
   • Lubricate the chassis according to the vehicle's manual.

   Answer: You check the oil on the dipstick with the engine cold, top up the water in the reservoir, change the filters according to the manual, change a tire with the jack, lubricate the chassis with grease at the indicated points. Always follow the vehicle's manual and use original parts. — Preventive automotive maintenance can increase the service life of the vehicle by up to 50% according to the Federation of Mechanical Engineers. Official manuals such as the Volkswagen Golf one specify the exact intervals for each type of maintenance in official detail.

6. How often should the engine oil, the transmission oil and the air conditioning fluid be changed?

   Answer: Engine oil: every 5,000-10,000 km or 6 months. Automatic transmission oil: 60,000 km or 4 years. Air conditioning fluid (gas): every 2-3 years or when cooling decreases. Always follow the specific vehicle's manual. — Maintenance intervals vary by model, with the Toyota Corolla being 10,000 km and the Volkswagen Gol 5,000 km for engine oil. Technical manuals in magazines such as Quatro Rodas detail specific schedules for each Brazilian model currently in use.

7. Present some suggestions for caring for the vehicle, both internally and externally.

   Answer: Exterior: wash regularly, wax quarterly, protect from the sun (covered garage), pay attention to small scratches, keep tires inflated. Interior: vacuum the carpets, clean the seats, do not smoke, avoid food in the car, protect the dashboard from the sun, keep it smelling fresh with safe and suitable automotive products. — Exterior cleaning: automotive shampoo (not ordinary soap). Wax protects the paint. The sun degrades rubber and paint. Scratches turn into rust. Interior: vacuum weekly, microfiber cloths, leather/seat conditioner. Food attracts insects. Dashboard: a sun shade on the windshield. Smell: proper air fresheners. Preventive maintenance preserves value. Adventism: care for the goods we receive.