Engine Parts

In the automobile, the engine is a source of power. It converts chemical energy of fuel into mechanical energy in the form of a rotative force to propel the qutomobile. Without the engine, the automobile will not operate; that is, it cannot move from one place to another.

The automotive engine can be divided into two major parts, the stationary parts and the moving jparts. The stationary parts are those that are fixed in a certain position. They do not move or change their position during engine operation. Moving parts are those that move or change their position during operation.

I. Engine Stationary Parts.

a. The cylinder head. The cylinder head covers the cylinders and is held to the cylinder block by bolts or nuts. It is cast from iron which is alloyed with other metals or cast from aluminum alloy. It contains the combustion chambers, water jackets on water cooled engines, cylinder head boltholes or stud holes, and the spark plug holes on gasoline engines or nozzle mounting holes on the diesel engines. It also contains some other parts such as the valve ports, valve seats, etc.

b. The cylinder head gasket. A water-tight and gas-tight seal beween the cylinder head and cylinder block is maintained through the use of a cylinder head gasket. This gasket may be in the form of a metal sheet, soft enough to be formed as required. In some cases, the cylinder head gasket is made from two thin plates of soft metals such as copper, with re-enforced asbestos filling beween. This gasket is provided with holes for the cylinder head bolts or studs and for the combustion spaces.

c. The combustion chambers. These are hollowed spaces within the cylinder head or above the pistons where the fuel charge is burned. They are made in different shapes designed to provide a more uniform and better mixture of air and fuel in order to obtain maximum combustion of the fuel.

d. The cylinder block. The cylinder block forms the main body or is referred to as the framework of the engine. It is cast from gray iron or iron alloyed with other metals like nickel and chromium or cast from aluminum. It contains the cylinders and the water jacket for the cooling water. In some types, the cylinder block also contains the valve ports, valve seats and valve mechanisms. In front are the water pump and the timing gear cover and at the rear is the bell housing or clutch housing. At the side of the block are the manifolds, fuel pump, distributor, etc.

e. The cylinders. The cylinders are cylindrical openings in the cylinder block where the pistons move up and down. They are usually provided with the cylinder liners or sleeves which are made from special types of metals, such as cast iron or steel. In some cases, the cylinders are not provided with sleeves; instead, they are parts integral with the cylinder block, and are plated with chromium to reduce wear and to lengthen their lives.

f. The crankcase. The crankcase is located at the bottom portion of the cylinder block and supports the crankshaft and camshaft by means of bearings. It contains the drilled oil passages for the lubricating oil and the oil pump.

g. The oil pan. Attached to the lower part of the crankcase is the oil pan. It encloses the lower portion of the engine and holds the lubricating oil. Without he oil pan, there is no means of storing the lubricating oil of the engine. The oil pan is provided with a drain plug to facilitate the drainage of lubricating oil when the lubricaing oil of the engine is changed

h. The manifolds. There are two kinds of manifolds used in the engine, the intake manifold and exhaust manifold.

The intake manifold provides a passage for the air-fuel mixture from the carburetor into the intake valve ports of the engine and also provides passage for the intake air for the diesel engine.

The exhaust manifold provides a passage for the burned gases coming out from the cylinders.

II. Engine Moving Parts

a. Pistons. Are the movable cylinder metal plugs. They are closed at the top and open at their bottom and are provided with grooves near their closed ends to accommodate the piston rings. They receive the force of explosion and transmit that force to the crankshaft through the connecting rod.

b. Piston rings. Are expanding ring placed in the piston grooves to provide a complete seal beween the piston and the cylinder wall. They prevent the leakage of fuel charge or explosion in the combustion chamber into the crankcase and control the lubricating oil from reaching the combustion chamber. In addition, they permit the proper lubrication of the cylinder and assist in cooling the piston.

c. Connecting rod. changes the reciprocating motion of the piston into a rotary motion. It is connected to the piston by a piston pin and to the crankshaft journal by a connecting rod cap and connecting rod bearings.

d. Crankshaft. is a cast of heat-treated alloy steel strong enough to withstand the downward thrust of the pistons cause by the force of explosion. It is provided with counterweights and drilled oil passages. The rear end is provided with a flange for the flywheel, and the front end carries the crankshaft gear of sprocket, vibration damper and fan belt pulley.

e. Flywheel. is a heavy wheel provided with a ring gear for starting and cranking. It provides for smooth rotations of the crankshaft even during non-power strokes and serves as the driving member of the clutch assembly.

f. Valves. allow the opening and closing of the ports while the engine is in operation. The inlet port has the intake valve to close it during the rest of the cycle and open it when the fuel is needed to enter the cylinder. The exhaust port has the exhaust valve to open the port when the burned gases go out from the combustion chamber.

g. Camshaft. is a straight shaft provided with cams to change rotary motion into a straight line motion. The cams of the camshaft cause the valves to open.