Reasons why the engine cylinder head is not tightly sealed (below)

Dec. 02, 2019

5. Uneven cooling of the cylinder surface

Non-uniform cooling of the cylinder surface will form local hot spots. Local hot spots can cause excessive expansion of the metal in the cylinder head or a small area on the cylinder block, which can squeeze and damage the cylinder head gasket. Leakage and corrosion caused by the damage of the cylinder pads, and eventually burned through.

If the cylinder head is replaced before the cause of the local hot spot is found, it will not help, because the replaced cylinder head will eventually burn out. Local hot spots also cause additional internal stress on the cylinder head itself, which results in cracks in the cylinder head. If the operating temperature exceeds the normal temperature, local hot spots will also have serious negative effects. Any overheating condition will cause permanent distortion of the cast iron parts of the cylinder block.

6. Problems related to additives in coolant

When the coolant is added to the coolant, bubbles may be generated. Air bubbles in the cooling system can cause cylinder head gaskets to fail. When there are air bubbles in the cooling system, the coolant cannot be circulated normally in the system, so the engine cannot be cooled uniformly, local hot spots will occur, and the cylinder gasket will be damaged, resulting in poor sealing. Therefore, in order to achieve uniform cooling of the engine, air must be discharged from the engine when the coolant is added.

Cylinder Head

Cylinder Head

7. Poor quality of diesel engine maintenance and assembly

The poor quality of engine maintenance and assembly is the main cause of the seal quality of the cylinder head of the engine, and also the main factor that causes the cylinder gasket to burn out. For this reason, when repairing the engine, we must strictly follow the relevant requirements and properly disassemble and assemble the cylinder head.

When disassembling and disassembling the cylinder head, it should be performed in a cold state, and it is strictly forbidden to disassemble in a hot state to prevent the cylinder head from warping and deforming. When disassembling, it should be loosened gradually from the two sides to the middle symmetrically.

When assembling the casting cylinder head, first remove the oil, carbon particles, rust and other impurities in the joint surface of the cylinder head and the cylinder, and in the bolt holes of the cylinder block, and blow it off with high pressure gas. In order to avoid insufficient pressure on the cylinder head by bolts. When tightening the cylinder head bolts, it should be tightened symmetrically from the middle to the sides 3 to 4 times. The last time to achieve the specified torque.

8.Use inappropriate fuel

Due to the different types of diesel engines, the cetane number of diesel has different requirements. If the selected fuel is not satisfactory, it will not only cause economic and power decline, but also cause a large amount of carbon deposition or abnormal combustion of the diesel engine, which will cause the local body temperature to be too high, causing the cylinder pads and the body to ablate Reduce the sealing performance of the aluminum cylinder head. Therefore, the choice of diesel cetane number of diesel engines must meet the requirements of use regulations.

9. Improper use of diesel engines

Some operators are afraid of the engine stalling, so they always bang the throttle continuously when starting the engine, or keep the engine running at high speed as soon as the engine is started to maintain the working state of the engine; Gear stalls and coasts, and then the gear is forced to start the engine. Engines operating under such conditions not only increase engine wear, but also cause the pressure in the cylinder to rise sharply, which can easily damage the cylinder gasket and cause a reduction in sealing performance. In addition, the engine is often overloaded and knocked for a long time, causing local pressure and temperature in the cylinder to be too high. At this time, the cylinder gasket is also damaged and its sealing performance is reduced.