When the engine is working, the oil in the oil pan is stirred by the crank to realize splash lubrication, and the oil is extracted by the oil pump to realize spray lubrication. When the piston is in the working stroke, the pressure in the cylinder can easily reach more than ten bar. These exhaust gases will flow into the crankcase through the piston ring, and also into the valve through the valve, causing the pressure rise in the valve and crankcase. When the flash point of the oil itself reaches about 235 degrees, it will deflagration and produce gas. The blow by gas in the cylinder and the gas produced by the engine oil will cause the pressure in the crankcase and the valve chamber to rise, which is a great loss for the engine, so the pressure must be relieved, and the PCV valve of the positive crankcase ventilation system is used for pressure relief. In addition, the crankcase also has a function of separating the oil in the steam, also known as the oil-gas separator.
The maximum vacuum pressure of 38mbar can be called out by the pressure regulating valve, so it can be seen that the pressure inside the crankcase is negative pressure. This negative pressure is not regulated by the oil pump, but by the PCV valve. Since it is negative pressure in most cases, why does crankshaft oil seal leak? The oil seal should be firmly absorbed on the crankshaft, and the sealing performance should be good.
There are three reasons for burning engine oil: piston ring, PCV valve and valve oil seal. Any problem will cause the pressure inside the crankcase to rise, leading to the increase of blowby. The increase of blowby can not be caught. The pressure relief of crankcase is still in accordance with the previous way, which is obviously not enough to meet the increasing pressure. When the pressure is high enough, some weak places will be pushed open by high pressure blowby, such as crankshaft oil seal, valve cover, etc. In these places, oil will leak first, so the main cause of the failure of the leaking gasket is high pressure.
So as long as the engine of the vehicle has oil leakage, there must be large or small oil burning. But some cars don't burn oil, and there will be oil leakage. This kind of car is very likely a German car. From the last century to today, the working temperature of the German car engine has risen by about 35 degrees. High temperature means that the flame burns fast and can output more power! So in order to achieve more engine power, we have to sacrifice some faults. The pressure inside the combustion chamber of the engine rises in a straight line, and the natural gas flow increases. At the same time, the high temperature will also aggravate the aging of the rubber material.
How much suction can the oil pump produce?
The oil pump sucks oil, not air. When the oil pump starts to draw air, there is no oil in the oil pan. Normally, this will not happen. If there is no oil in the oil pan, the engine will suddenly lock up, let alone give the oil pump a chance to absorb the sealant on the oil seal. It only takes a few minutes for the engine to stop completely.
Oil seal coating
Gluing is not the manufacturer's maintenance process. The engines of the main engine factory are all cold installed, the oil seal is relatively easy to install, and there is basically no possibility of damage. The purpose of gluing is to ensure the smooth installation of the oil seal. The requirement of oil seal installation position is very high. If the rubber oil seal is installed slightly, it will cause loose seal and damage the oil seal. The sealant is mainly used for lubrication. Although it is assisted by special tools, the damage probability is still very high. So we can only use some soil methods to slightly reduce the damage rate.