What are the symptoms of a damaged cylinder gasket? How to prevent the cylinder gasket from burning and being damaged?

Engine cylinder gasket burning and compression system leakage are common failures. After the cylinder gasket is burned, the working condition of the engine will be seriously deteriorated to the point that it cannot work, and it may also cause damage to some related parts or parts. During the compression and power stroke of the engine, the sealing of the upper space of the piston must be ensured to be intact. , no air leakage. Combined with the signs and symptoms that occur after the cylinder gasket is burned and the compression system leaks, analyze and determine the causes of the failure signs, and point out the operation methods to prevent the failure and effectively eliminate the failure.





What are the symptoms of a damaged cylinder gasket?
Due to the different locations of the cylinder gasket burnt, the symptoms of failure are also different:
(1) Air blow-by between two adjacent cylinders.
Without turning on the decompression, crank the crankshaft and feel that the pressure in both cylinders is not enough. When starting the engine, black smoke appears, and the engine speed drops significantly, indicating insufficient power.



(2) Air leakage in cylinder head
The compressed high-pressure gas flows into the bolt holes of the cylinder head or leaks from the joint surface of the cylinder head and the body. There is light yellow foam in the air leakage area. When the air leakage is serious, it will make a "buzzing" sound, sometimes accompanied by water leakage or oil leakage. When disassembling and inspecting, you can see the corresponding cylinder head plane and its vicinity. There is obvious carbon deposits in the bolt holes of the cylinder head.



(3) In the gas oil passage
The high-pressure gas rushes into the lubricating oil passage connecting the engine body and the cylinder head. The temperature of the oil in the oil pan is always high when the engine is running. The viscosity of the oil becomes thinner, the pressure decreases, and it deteriorates quickly. There are obvious bubbles in the oil sent to the upper part of the cylinder head to lubricate the valve mechanism.



(4) High-pressure gas escapes into the cooling water jacket.
When the engine cooling water temperature is lower than 50°C, if you open the water tank cover, you can see obvious bubbles rising and emerging from the water tank, and at the same time, a large amount of hot air is emitted from the water tank mouth. As the engine temperature gradually increases, The heat emitted from the water tank mouth also gradually increased. In this case, if the overflow pipe of the water tank is blocked and the water tank is filled with water to the cover, the phenomenon of bubbles rising will become more obvious, and in severe cases, it will appear like boiling.



(5) The engine cylinder is connected with the cooling water jacket or lubricating oil channel.
There will be yellow-black oil foam floating on the upper surface of the cooling water in the water tank or there will be obvious water in the oil in the oil pan. When these two blow-by phenomena are serious, water or oil will be contained in the exhaust.





Analysis of the causes of damaged cylinder gasket
(1) The cylinder head bolts and nuts are elongated or loose.
Due to the extrusion deformation of the joint surface between the cylinder head and the engine body, the compression deformation of the cylinder gasket, the accidental overload caused by the pressure of high-pressure gas on the cylinder head bolts and nuts, the cylinder head bolts are not screwed into the depth enough, and the microscopic unevenness of the thread surface is suppressed. Flat and bolt necking due to excessive torque can cause the cylinder head bolts and nuts to be elongated or loose, resulting in insufficient pressure at the joint surface between the cylinder head and the engine body and uneven pressure everywhere, causing high-temperature and high-pressure gases to flow from local areas. The parts with less pressure escape and burn out the cylinder gasket.



(2) The joint surface between the cylinder head and the engine body is deformed.
If these two joint surfaces are deformed, it will not be possible to ensure that the cylinder gasket is evenly compressed, causing air leakage and burning of the cylinder gasket. This is also the main reason for burning of the cylinder gasket.



(3) The installation does not meet the technical requirements.


During installation, the joint surface of the cylinder gasket is not clean, the order of tightening the cylinder head bolts and nuts is incorrect, the torque is not large enough or uneven, and the upper end surface of each cylinder liner is not higher than the upper plane of the engine body in an insufficient or unequal size, causing air leakage and burning damage. Cylinder gasket.



(4) The engine is overheated.
The engine cooling system is not working properly, the oil supply time is too late, and the engine is overloaded for a long time, etc., which will cause the engine to overheat, especially the temperature between the intake and exhaust valve seats of the cylinder head and the outlet of the vortex chamber channel is higher. Due to the high temperature As a result, the cylinder gasket loses its original elasticity and becomes brittle, and is eventually burned.



(5) The quality of the cylinder gasket itself is unqualified.
Such as uneven thickness, uneven crimping, insufficient elasticity, poor materials, uneven surface, etc., or careless damage to the cylinder gasket during disassembly and assembly, can easily cause the cylinder gasket to burn.

Methods to prevent cylinder gasket from burning and being damaged


(1) The warpage of the two joint surfaces of the cylinder head and engine body should be strictly checked before installation.
(2) Check whether the protrusion height of the upper end surface of each cylinder liner on the upper plane of the engine body is high enough.