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    The reasons for the tightness of the engine cylinder head are here

    Word:[Big][Middle][Small] QR Code 2017/8/24     Viewed:    


    Cylinder head seal lax reasons

    The reasons for the tightness of the engine cylinder head are here

    Cylinder head sealing performance is good or bad, the technical conditions of the engine have a great impact. When the cylinder head seal is not strict, the cylinder will leak, resulting in insufficient compression pressure cylinder, lower temperature and air quality. Cylinder leaks serious, will make the engine power significantly decreased, or even unable to work. Therefore, in the engine work if the power failure failure, in addition to find the impact of the engine power down the cause of the failure, but also check the cylinder head sealing performance is good. The following Xiaobian will affect the engine cylinder head sealing performance of the main reasons for analysis, for reference.

    1. The use and installation of the cylinder pad is not correct

    Cylinder pad is installed between the engine cylinder block and the cylinder head, its role is to ensure that the combustion chamber of the seal, to prevent gas, cooling water and lubricants jump leakage. Therefore, the use of the cylinder pad and installation does not meet the requirements, it directly affects the cylinder head sealing reliability and cylinder pad life.

    In order to ensure the quality of the seal, the choice of cylinder pad must be with the original cylinder with the same specifications and thickness, the surface should be flat, tight fit, and no scratches, depression, wrinkles and rust and so on. Otherwise, it will affect the quality of the cylinder head seal.

    2. Cylinder head slightly beating

    The slight beating of the cylinder head is the result of the separation of the cylinder head from the cylinder under the action of compression and combustion pressure. These pressures extend the cylinder head connecting bolts, thus causing the cylinder head to have a slight beating relative to the cylinder. This slight beating will cause the cylinder head gasket to relax and compact the process, thus accelerating the cylinder head gasket damage, affecting its sealing performance.

    3, the cylinder head connection bolt does not meet the specified torque value

    If the cylinder head connection bolts are not tightened to the specified torque values, the cylinder pad wear caused by this slight beating will occur faster and more seriously. If the connecting bolts are too loose, it will cause the cylinder head to increase relative to the cylinder runout. If the connecting bolts are tightened tightly, the force of the connecting bolts will exceed the limit of its yield strength, resulting in the elongation of the connecting bolts exceeding its design tolerance, which can also cause an increase in the beating of the cylinder head , To accelerate the wear of the cylinder head gasket. Using the correct torque rating and tightening the connecting bolts in the correct order allows the cylinder head to be minimized against the beating of the cylinder, ensuring the seal quality of the cylinder head.

    4, cylinder head or cylinder flatness is too large

    Warping and twisting are often problems with cylinder heads, and are the main cause of the cylinder pad. In particular, aluminum alloy cylinder head performance is more prominent, it is because the aluminum alloy material has a high heat transfer efficiency, while the cylinder head and the cylinder block, it is relatively small and thin, aluminum alloy cylinder head temperature rise faster The When the cylinder head is deformed, it is not tightly engaged with the cylinder surface, the seal quality of the cylinder is reduced, causing leakage and burning the cylinder pad, thereby further deteriorating the seal quality of the cylinder. If the cylinder head is seriously warped, it must be replaced.

    5, the cylinder surface cooling is not uniform

    Uneven cooling of the cylinder surface will form a local hot spot. Local hot spots can cause excessive expansion of the metal in the cylinder head or small area on the cylinder block, which causes the cylinder head seal to be squeezed and damaged. Damage and corrosion are caused by damage to the cylinder pad and are eventually burned.

    If you have not found the cause of local hot spots when the replacement of the cylinder pad, it will be of no avail, because the replacement of the cylinder pad will eventually be burned out. The local hot spot also causes the cylinder head itself to generate additional internal stresses, with the result that the cylinder head is cracked. If the operating temperature exceeds the normal temperature, local hot spots will also have a serious negative impact. Any overheating conditions can cause permanent damage to the cylinder block cast iron.

    6, the coolant additives related issues

    When coolant is added to the coolant, bubbles may be generated. Bubbles in the cooling system can cause the cylinder head seal to fail. When the cooling system in the bubble, the coolant can not be in the system for normal circulation, so the engine can not get a uniform cooling, there will be local hot spots, the cylinder pad damage, resulting in poor sealing. Therefore, in order to be able to achieve uniform cooling of the engine, adding coolant, the air must be discharged from the engine.

    Some hand in the winter use of antifreeze, summer when changing water, that this is affordable. In fact, this is endless trouble, because the water is easy to produce scale and floating in the water jacket, radiator and water temperature sensor, the engine temperature control inaccurate lead to overheating, and even cause the engine cylinder pad rupture, cylinder head warping deformation , Pull cylinder and burner and other failures. Therefore, antifreeze should also be used in summer.

    7, diesel engine repair, poor assembly quality

    Poor maintenance and assembly of the engine is the main cause of the quality of the engine cylinder head seal, but also the main cause of cylinder pad burning. To this end, in the repair engine, we must strictly in accordance with the requirements to do, to properly disassemble the cylinder head.

    In the disassembly of the cylinder head, should be carried out in the cold state, is strictly prohibited in the heat state to remove, to prevent the cylinder head warping deformation. Demolition should be from the two sides to the middle symmetrical points gradually loose. If the cylinder head and the cylinder block firmly removed difficult, it is strictly prohibited with metal objects or with sharp hard objects embedded in the seam hard pry (the effective way is to use the starter to drive the crankshaft rotation or rocking crankshaft rotation, generated by the cylinder Of the high-pressure gas to open it) to prevent scratching the cylinder and the cylinder head of the joint surface or damage the cylinder pad.

    When assembling the cylinder head, first remove the oil, carbon, rust and other impurities from the engagement surface of the cylinder head with the cylinder and the cylinder block bolt hole and clean it with high pressure gas. So as to avoid the lack of bolts on the cylinder head. When tightening the cylinder head bolts, should be 3-4 times from the middle to the two sides symmetrical tightening, the last time to achieve the required torque, and the error ≯ 2%, for the cast iron cylinder head in the heat engine temperature reaches 80 ℃, Set the torque and tighten the connection bolts again. For bimetallic engine, it should be in the engine after cooling, and then such a re-tightening operation.

    8, the choice of inappropriate fuel

    Due to the different types of diesel engines, the cetane number of diesel has different requirements. If the fuel used is not meet the requirements, not only will cause economic and dynamic decline, but also cause a lot of diesel engine coke or abnormal combustion, resulting in the local temperature is too high, resulting in cylinder pad and body ablation, So that the sealing performance of the cylinder head. Therefore, the choice of diesel engine cetane number must meet the requirements of the use of the requirements.

    9, improper use of diesel engine

    There are some machine hand for fear of engine flameout, so when the engine starts, always continuous throttle throttle, or when the engine starts to let the engine high-speed operation, in order to maintain the engine working state; in the course of running, often off Stall off the taxi, and then pull the file to start the engine. The engine operating in this case not only increases the wear of the engine, but also causes a sharp increase in the pressure inside the cylinder, which easily breaks the cylinder pad, resulting in a decrease in sealing performance. In addition, the engine often work overload (or ignition too early), long bursting combustion, resulting in the cylinder of local pressure and temperature is too high, this time also damage the cylinder pad, so that the sealing performance.

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