The following sections present a brief explanation of the systems that help an engine run and keep running.
LUBRICATION SYSTEM
The moving parts of an engine need constant lubrication. Lubrication limits the amount of wear and reduces the amount of friction in the engine. Friction, which occurs when two objects rub against each other, generates heat. Motor or engine oil is the fluid used to lubricate the engine. Several quarts of oil are stored in an oil pan bolted to the bottom of the engine block. The oil pin is also called the crankcase or oil sump. When the engine is running, an oil pump draws oil from the pan and forces it through oil galleries, which are small passageways that direct the oil to the moving parts of the engine. oil from the pan passes through an oil filter before moving through the engine. The filter removes dirt and metal particles from the oil. Premature wear and damage to parts can result from dirt in the oil. Regular replacement of the oil filter and oil is an important step in a preventive maintenance program.
Cooling System
The burning of the air/fuel mixture in the combustion chambers of the engine produces large amounts of heat. This heat must not be allowed to build up and must be reduced or it can easily damage and warp the metal parts of an engine. To prevent this, engines have a cooling system. The most common way to cool an engine is to circulate a liquid coolant through passages in the engine block and cylinder head. An engine can also be cooled by passing air over and around the engine. Few air-cooled engines are used in automobiles today because it is very difficult to maintain a constant temperature at the cylinders. If the engine is kept at a constant temperature, it will run more efficiently. A liquid cooling system also has a supply of hot coolant available to operate a heater for the passenger compartment. The cooling system is designed to cool the engine, not the passengers inside the car. Cooling the passengers is the responsibility of the air-conditioning system. A typical cooling system relies on a water pump that circulates the coolant through the system. The pump is typically driven by the engine. The coolant, a mixture of water and antifreeze, is pushed through passages called water jackets in the cylinder block and head to remove heat from the area around the cylinders’ combustion chambers. The heat picked up by the coolant is sent to the radiator that transfers the coolant’s heat to the outside air as the coolant flows through its tubes. To help remove the heat from the coolant, a cooling fan is used to pull cool outside air in through the fins of the radiator. To raise the boiling point of the coolant, the cooling system is pressurized. To maintain this pressure, a radiator or pressure cap is fitted to the radiator. A thermostat is used to block off circulation in the system until a preset temperature is reached. This allows the engine to warm up faster. The thermostat also keeps the engine temperature at a predetermined level. Since parts of the cooling system are located in various spots under the vehicle’s hood, hoses are used to connect these parts and keep the system sealed.
Fuel and Air System
The fuel and air system is designed to supply the correct amount of fuel mixed with the correct amount of air to the cylinders of the engine. This system also stores the fuel for later use. collects and cleans the outside air.
delivers fuel to a device that will control the amount of fuel going to the engine.
breaks down the fuel into very fine droplets and mixes the fuel with air to form a vapor.
changes the fuel and air ratios to meet the needs of the engine during different operating conditions.
The fuel system is made up of several different parts. A fuel tank stores the liquid gasoline. Fuel lines carry the liquid from the tank to the other parts of the system. A pump moves the gasoline from the tank through the lines. A filter removes dirt or other particles from the fuel. A fuel pressure regulator keeps the pressure below a specified level. An air filter cleans the out-side air before it is delivered to the cylinders. Fuel injectors or a carburetor mix the liquid gasoline with air for delivery to the cylinders. An intake manifold directs the air/fuel mixture to each of the cylinders.
Emission Control System
In the past, one of the chief contributors to air pollution was the automobile. For some time now, engines have been engineered to emit very low amounts of certain pollutants. The pollutants that have been drastically reduced are hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen NOx).
The Environmental Protection
Agency establishes emissions standards that limit the amount of these pollutants a vehicle can emit. To meet these standards, many changes have been made to the engine itself. Moreove4 there have been systems developed and added to the engines to reduce the pollutants they emit. A list of the most common pollution-control devices follows:
Positive crankcase ventilation (PCV) system. This system reduces HC emissions by drawing fuel and oil vapors from the crankcase and sending them into the intake manifold, where they are delivered to and burned in the cylinders. This system prevents the pressurized vapors from escaping the engine and entering the atmosphere.
Evaporative emission control system. This system reduces HC emissions by drawing fuel vapors from the fuel system and releasing them into the intake air to be burned. This system stops the vapors from leaking into the atmosphere.
Exhaust gas recirculation (EGR) system. This system introduces exhaust gases into the intake air to reduce the temperatures reached during combustion. This reduces the chances of NOx forming during combustion.
Catalytic converter. Located in the exhaust system, the catalytic converter allows for the burning or converting of HC, CO, and NOx into harmless substances, such as water.
Air injection system. This system reduces HC emissions by introducing fresh air into the exhaust stream to cause minor combustion of the HC in the engine’s exhaust.
Exhaust System
During the exhaust stroke, the engine’s pistons move up and push the burned air/fuel mixture, or exhaust, out of the combustion chamber and into the exhaust manifold. From the manifold, the gases travel through the other parts of the exhaust system until they are expelled into the atmosphere. The exhaust system is designed to direct toxic exhaust fumes away from the passenger compartment, to quiet the sound of the exhaust pulses, and to burn or catalyze pollutants in the exhaust. A typical exhaust system contains the following components:
Exhaust manifold and gasket
Exhaust pipe, seal, and connector pipe
Intermediate pipes
Catalytic converter(s)
Muffler
Resonator
Tailpipe
Heat shields
Clamps, gaskets, and hangers
Electrical and electronic System
Automobiles have many circuits that carry electrical current from the battery to individual components. The total electrical system includes such major subsystems as the ignition system, starting system, charging system, and the lighting and other electrical systems.
IGNITION SYSTEM
After the air/fuel mixture has been delivered to the cylinder and compressed by the piston, it must be ignited. A gasoline engine uses an electrical spark to ignite the mixture. Generating this spark is the role of the ignition system.
The ignition coil generates the electricity that creates this spark. The coil transforms the low voltage of the battery into a burst of 30,000 to 100,000 volts. This burst is what ignites the mixture. The mixture must be ignited at the proper time in order for complete combustion to occur. Although the exact proper time varies with engine design, ignition must occur at a point before the piston has completed its compression stroke. On most engines, the motion of the piston and the rotation of the crankshaft are monitored by a crankshaft position sensor. The sensor electronically tracks the position of the crankshaft and relays that information to an ignition control module. Based on input from the crank-shaft position sensor, and, in some systems, the electronic engine control computer, the ignition control module then turns the battery current to the coil on and off at precisely the right time so that the voltage surge arrives at the cylinder at the right time. The voltage surge from the coil must be distributed to the correct cylinder, since only one cylinder is fired at a time. In earlier systems, this was the job of the distributor. A distributor is driven by a gear on the camshaft at one-half of the crankshaft speed. It transfers the high- voltage surges from the coil to the spark plug wires in the correct firing order. The spark plug wires then deliver the high voltage to the spark plugs, which are screwed into the cylinder head. The voltage jumps across a space between two electrodes on the end of each spark plug and causes a spark. This spark ignites the air/fuel mixture. Today, most ignition systems do not have a distributor. Instead, these systems have several coils-typically one for each pair of spark plugs. When a coil is activated by the electronic control module, high voltage is sent through the spark plug circuit. Each spark plug circuit includes two spark plugs, which fire at the same time. One spark plug fires during the compression stroke of a cylinder and the other fires during the exhaust stroke of another cylinder and is wasted. In this way, the electronic control module controls both the timing and the distribution of the coil's spark-producing voltage.
LUBRICATION SYSTEM
The moving parts of an engine need constant lubrication. Lubrication limits the amount of wear and reduces the amount of friction in the engine. Friction, which occurs when two objects rub against each other, generates heat. Motor or engine oil is the fluid used to lubricate the engine. Several quarts of oil are stored in an oil pan bolted to the bottom of the engine block. The oil pin is also called the crankcase or oil sump. When the engine is running, an oil pump draws oil from the pan and forces it through oil galleries, which are small passageways that direct the oil to the moving parts of the engine. oil from the pan passes through an oil filter before moving through the engine. The filter removes dirt and metal particles from the oil. Premature wear and damage to parts can result from dirt in the oil. Regular replacement of the oil filter and oil is an important step in a preventive maintenance program.
Cooling System
The burning of the air/fuel mixture in the combustion chambers of the engine produces large amounts of heat. This heat must not be allowed to build up and must be reduced or it can easily damage and warp the metal parts of an engine. To prevent this, engines have a cooling system. The most common way to cool an engine is to circulate a liquid coolant through passages in the engine block and cylinder head. An engine can also be cooled by passing air over and around the engine. Few air-cooled engines are used in automobiles today because it is very difficult to maintain a constant temperature at the cylinders. If the engine is kept at a constant temperature, it will run more efficiently. A liquid cooling system also has a supply of hot coolant available to operate a heater for the passenger compartment. The cooling system is designed to cool the engine, not the passengers inside the car. Cooling the passengers is the responsibility of the air-conditioning system. A typical cooling system relies on a water pump that circulates the coolant through the system. The pump is typically driven by the engine. The coolant, a mixture of water and antifreeze, is pushed through passages called water jackets in the cylinder block and head to remove heat from the area around the cylinders’ combustion chambers. The heat picked up by the coolant is sent to the radiator that transfers the coolant’s heat to the outside air as the coolant flows through its tubes. To help remove the heat from the coolant, a cooling fan is used to pull cool outside air in through the fins of the radiator. To raise the boiling point of the coolant, the cooling system is pressurized. To maintain this pressure, a radiator or pressure cap is fitted to the radiator. A thermostat is used to block off circulation in the system until a preset temperature is reached. This allows the engine to warm up faster. The thermostat also keeps the engine temperature at a predetermined level. Since parts of the cooling system are located in various spots under the vehicle’s hood, hoses are used to connect these parts and keep the system sealed.
Fuel and Air System
The fuel and air system is designed to supply the correct amount of fuel mixed with the correct amount of air to the cylinders of the engine. This system also stores the fuel for later use. collects and cleans the outside air.
delivers fuel to a device that will control the amount of fuel going to the engine.
breaks down the fuel into very fine droplets and mixes the fuel with air to form a vapor.
changes the fuel and air ratios to meet the needs of the engine during different operating conditions.
The fuel system is made up of several different parts. A fuel tank stores the liquid gasoline. Fuel lines carry the liquid from the tank to the other parts of the system. A pump moves the gasoline from the tank through the lines. A filter removes dirt or other particles from the fuel. A fuel pressure regulator keeps the pressure below a specified level. An air filter cleans the out-side air before it is delivered to the cylinders. Fuel injectors or a carburetor mix the liquid gasoline with air for delivery to the cylinders. An intake manifold directs the air/fuel mixture to each of the cylinders.
Emission Control System
In the past, one of the chief contributors to air pollution was the automobile. For some time now, engines have been engineered to emit very low amounts of certain pollutants. The pollutants that have been drastically reduced are hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen NOx).
The Environmental Protection
Agency establishes emissions standards that limit the amount of these pollutants a vehicle can emit. To meet these standards, many changes have been made to the engine itself. Moreove4 there have been systems developed and added to the engines to reduce the pollutants they emit. A list of the most common pollution-control devices follows:
Positive crankcase ventilation (PCV) system. This system reduces HC emissions by drawing fuel and oil vapors from the crankcase and sending them into the intake manifold, where they are delivered to and burned in the cylinders. This system prevents the pressurized vapors from escaping the engine and entering the atmosphere.
Evaporative emission control system. This system reduces HC emissions by drawing fuel vapors from the fuel system and releasing them into the intake air to be burned. This system stops the vapors from leaking into the atmosphere.
Exhaust gas recirculation (EGR) system. This system introduces exhaust gases into the intake air to reduce the temperatures reached during combustion. This reduces the chances of NOx forming during combustion.
Catalytic converter. Located in the exhaust system, the catalytic converter allows for the burning or converting of HC, CO, and NOx into harmless substances, such as water.
Air injection system. This system reduces HC emissions by introducing fresh air into the exhaust stream to cause minor combustion of the HC in the engine’s exhaust.
Exhaust System
During the exhaust stroke, the engine’s pistons move up and push the burned air/fuel mixture, or exhaust, out of the combustion chamber and into the exhaust manifold. From the manifold, the gases travel through the other parts of the exhaust system until they are expelled into the atmosphere. The exhaust system is designed to direct toxic exhaust fumes away from the passenger compartment, to quiet the sound of the exhaust pulses, and to burn or catalyze pollutants in the exhaust. A typical exhaust system contains the following components:
Exhaust manifold and gasket
Exhaust pipe, seal, and connector pipe
Intermediate pipes
Catalytic converter(s)
Muffler
Resonator
Tailpipe
Heat shields
Clamps, gaskets, and hangers
Electrical and electronic System
Automobiles have many circuits that carry electrical current from the battery to individual components. The total electrical system includes such major subsystems as the ignition system, starting system, charging system, and the lighting and other electrical systems.
IGNITION SYSTEM
After the air/fuel mixture has been delivered to the cylinder and compressed by the piston, it must be ignited. A gasoline engine uses an electrical spark to ignite the mixture. Generating this spark is the role of the ignition system.
The ignition coil generates the electricity that creates this spark. The coil transforms the low voltage of the battery into a burst of 30,000 to 100,000 volts. This burst is what ignites the mixture. The mixture must be ignited at the proper time in order for complete combustion to occur. Although the exact proper time varies with engine design, ignition must occur at a point before the piston has completed its compression stroke. On most engines, the motion of the piston and the rotation of the crankshaft are monitored by a crankshaft position sensor. The sensor electronically tracks the position of the crankshaft and relays that information to an ignition control module. Based on input from the crank-shaft position sensor, and, in some systems, the electronic engine control computer, the ignition control module then turns the battery current to the coil on and off at precisely the right time so that the voltage surge arrives at the cylinder at the right time. The voltage surge from the coil must be distributed to the correct cylinder, since only one cylinder is fired at a time. In earlier systems, this was the job of the distributor. A distributor is driven by a gear on the camshaft at one-half of the crankshaft speed. It transfers the high- voltage surges from the coil to the spark plug wires in the correct firing order. The spark plug wires then deliver the high voltage to the spark plugs, which are screwed into the cylinder head. The voltage jumps across a space between two electrodes on the end of each spark plug and causes a spark. This spark ignites the air/fuel mixture. Today, most ignition systems do not have a distributor. Instead, these systems have several coils-typically one for each pair of spark plugs. When a coil is activated by the electronic control module, high voltage is sent through the spark plug circuit. Each spark plug circuit includes two spark plugs, which fire at the same time. One spark plug fires during the compression stroke of a cylinder and the other fires during the exhaust stroke of another cylinder and is wasted. In this way, the electronic control module controls both the timing and the distribution of the coil's spark-producing voltage.
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