Cylinder head gasket
The cylinder head gasket is located between the engine and the cylinder head and assumes the most critical sealing function in the engine, preventing engine failure caused by the fusion of gasoline and water. In general, automotive engine internal combustion engines use a water-cooled gasoline four-stroke design in which three circulating circuits, flammable air or fuel mixture, aqueous coolant mixed with ethylene glycol, and lubricating oil are important. However, once the materials of the three circulating circuits are mixed together, it will cause the engine to overheat, the oil burns or the coolant burns.
If the cylinder head fails, the following series of problems will occur:
(1) Reduced compression force - The car's power will be reduced or the engine will be unstable.
(2) Exhaust gas is forced into the cooling system - causing the oil and coolant to mix, increasing engine wear and making it susceptible to overheating.
(3) Leakage of coolant to the cylinder (internal leakage) - can cause exhaust pipe problems and damage to the catalytic converter. In addition, a large amount of coolant leaking into the cylinder can also cause hydraulic locking problems, causing large-scale damage to the engine.
(4) External leakage - Gasoline and coolant accumulate under the engine.
(5) Compressive force leaks into the small gap between the engine and the cylinder head gasket - When the engine is extinguished, these trapped air will run into the coolant to create air bubbles. If these bubbles are trapped in the engine cooling temperature controller, severe engine overheating will occur, and the gap between the cylinder head gasket and the engine will gradually increase.
All of the above are related to the failure of the cylinder head gasket. Sometimes, the driver can still drive normally when the exhaust pipe emits too much exhaust gas until all the coolant is used up, eventually causing the engine to overheat.
The cylinder head gasket can be roughly divided into the following four types:
(1) Multilayer iron cylinder gaskets - the most common modern engine cylinder head gasket. It usually consists of three layers of iron: the top layer is rubber surface coating (layer), the contact surface (layer) has wave-stopper technology, the bottom layer is fully painted and the exterior is partially painted.
(2) Solid copper cylinder head gasket - The cylinder head made of solid copper is extremely durable. However, it requires special O-ring processing techniques to place a coil around the cylinder ring to fit over the copper.
(3) Composite cylinder head gasket - Older cylinder head gasket made of asbestos and graphite. Due to health considerations, the use of such cylinder heads is gradually reduced.
(4) Elastic Cylinder Gasket - This cylinder head gasket is typically used in the Rover Group's K-Series engines. Its cylinder head design is used in the F1 sports car to achieve unprecedented success. However, this design has a persistent phenomenon that cannot be solved at present, and the cylinder head gasket cannot cope with the problem of unstable joint surface.
A pressure gauge or leak test can be used to view the condition of the cylinder head gasket. At the same time, when the exhaust pipe starts to emit white smoke or blue smoke, it is time to replace the cylinder head gasket. Although the cost of the cylinder head is not high, the replacement of the cylinder head is very time consuming, so the labor cost accounts for 75% of the near cost. In addition, unmaintained cylinder head gaskets can cause even greater damage to the engine, which in turn requires higher maintenance costs.