The cylinder head plays an important role in the general operation of a vehicle’s engine.
It is a complex structure, consisting of many ports and passageways. Each with a, specific purpose to serve. Consequently, their collective roles define the importance of this engine part.
The main cylinder head functions are:
- Provide the mounting structure for various components such as: the inlet and outlet exhaust valves, spark plugs, injectors, and camshaft.
- Contain the passages for coolant, oil, and combustion gases.
- Dissipate the heat produced by the engine and, therefore, produce cooling.
- Act as the combustion chamber seal and the engine’s mechanical control center.
- Take the compression, resulting from combustion pressure.
So, the passages in the cylinder head, allow air and fuel to flow inside the cylinder; while permitting the exhaust gases to flow out of it. Furthermore, channeling the coolant into the engine block; thereby cooling down the engine components. Consequently, the cylinder head uses a gasket, that aids in preventing water or oil; from leaking into the combustion chambers.
These are the components of a cylinder head, in a gasoline engine
Inlet and exhaust ports:
These ensure that the exhaust gas, can escape from the cylinders and the absorbed air-fuel mixture; can get into the cylinders.
Inlet and exhaust valves:
This is where gas engines suck an air-fuel mixture in. While, exhaust gases are, simultaneously transported to the exhaust system.
Camshafts:
A crankshaft driven by the timing belt, drives the camshafts. Consequently, the camshafts are responsible for, opening and closing the valves.
Injectors:
Consequently, they ensure that the fuel is, injected into the combustion chambers.
Spark plugs:
Consequently, they initiate the combustion of the fuel.
These are the components of a cylinder head, in a diesel engine
Inlet and exhaust ports:
They allow exhaust gas to, escape from the cylinders and allow the captured air-fuel mixture, to enter the cylinders.
Inlet and exhaust valves:
Diesel engines, suck air in through the inlet and exhaust valves while exhaust gases are, simultaneously transported to the exhaust system.
Camshafts:
A crankshaft driven by the timing chain drives the camshafts. The camshafts are responsible for, opening and closing the valves.
Injectors:
These inject the fuel in diesel engines into the combustion chambers or antechambers.
Glow plugs:
They act as a, cold-start aid.
So, most OEM (original equipment manufacturer) cylinder heads, are made out of cast-iron. Because, a cylinder head made of cast-iron is, more durable and less expensive. However, cast-iron is heavy and provides a lesser efficiency, in dissipating heat. For this reason, some manufacturers prefer using cylinder heads, made of aluminum. These cylinder heads are, much lighter, than cast-iron cylinder heads. Therefore, performance cars and race cars, commonly have aluminum cylinder heads.
Cylinder Head Types
Flathead Cylinder Heads:
These were the first type of cylinder heads. Flathead cylinder heads simply, protect the cylinder block and have no moving parts. These cylinder heads do not allow for an efficient air flow. And, as a result, provide poor engine performance.
Overhead Valve Cylinder Heads:
These cylinders heads are, superior to flathead cylinder heads. Overhead valve cylinder heads, have the camshafts below them. These heads have their, pushrods and valves connected, to provide a smooth airflow.
Overhead Camshaft Cylinder Heads:
These are the most, advanced designs of cylinder heads. Overhead camshaft cylinder heads, have the camshafts inside the cylinder head. As a result, eliminating the need of pushrods. This provides a better airflow, and in turn, increases the efficiency of the engine.
Problems in Cylinder Heads and their Symptoms
So, the most common problem with cylinder heads is, cracks that occur due to engine overheating. A cracked cylinder head could leak engine coolant. As a result, further overheating the engine. Furthermore, when a cylinder head cracks; it can cause the oil to leak into the combustion chambers. This can be detrimental to the engine and can result in, costly repairs for the engine. And, in many of these cases, the entire engine may have to be replaced. Other symptoms of a bad cylinder head include: poor engine performance and engine misfire.
