AY Honors/Automobile Mechanics/Answer Key

Skill Level 2

1. Properly start an automobile or light truck engine with an automatic transmission and one with a standard transmission. Explain why it is necessary for the engine to have the proper oil, water, fuel, and battery pressures and levels for proper engine operation.

Starting an Automatic

To start a vehicle with an automatic transmission, sit in the driver's seat and make sure the vehicle is in Park. Insert the key in the ignition and turn it clockwise as far as it will go. The engine should crank. Do not depress the gas pedal. As soon as the engine starts, release the key. To turn it off, turn the key counter-clockwise.

Starting a Manual

To start a vehicle with a manual transmission, sit in the driver's seat and push on the clutch pedal. Make sure the parking brake has been applied. Inexperienced drivers should also shift the vehicle into neutral so that if the foot slips off the clutch after the engine starts, the car does not move. Insert the key in the ignition and turn it clockwise as far as it will go. The engine should crank. Do not depress the gas pedal, but leave the clutch pedal depressed. As soon as the engine starts, release the key. To turn it off, turn the key counter-clockwise.

Importance of Proper Pressures and Levels

Oil keeps the engine lubricated and reduces friction between the moving parts of the engine. Friction causes heat, so if there is insufficient oil pressure in the engine, it will quickly overheat. Running an engine without oil for any amount of time will damage it, and doing so for an extended period will destroy it.

Water circulates through the engine to cool it. Running an engine too hot will dmage it.

Fuel is what makes the engine go. If the vehicle has insufficient fuel pressure, the fuel will not flow into the combustion chamber at the proper rate.

The Battery provides energy to run the engine's starter. If the battery's volatage level is low, it will not be able to turn the starter.

2. Explain the principles of four- and two-cycle engines and the difference between gasoline and diesel engines. Explain the major differences between carburetor fuel systems and fuel-injection systems.

==3. Describe the construction of a typical gasoline engine and explain briefly the function of these units:== ===a. Engine: crankshaft, connecting rods, pistons, camshaft, valves, oil pump, carburetor, fuel injectors, ignition distributor, fuel distributor, electrical system including alternator, battery, and regulator=== ===b. Difference between standard transmission and automatic transmission and how the engine torque is transmitted to both kinds of transmissions; the purpose of overdrive===