There are some misunderstandings in automobile maintenance. These erroneous zones are gradually formed in the age of low automobile manufacture, backward vehicle repair technology and lack of testing means. In recent years, with the rapid development of science and technology, with the wide use of new materials, new technologies and new technologies, the design and manufacturing level of automobile has been greatly improved. The technology of auto failure detection and diagnosis is becoming more mature, and automobile maintenance technology is constantly updated. However, people's understanding is lagging behind the development of science and technology, and the remaining misunderstandings in automobile maintenance have a great influence. There are 10 main manifestations as follows: 1. the axle bush of the sliding bearing must be scraped. It is considered that the crankshaft bearing of the engine, the shaft bearing must be scraped when the connecting rod bearing is new, and the non chipping bearing can not guarantee a good contact surface, and even the scraping axle is regarded as the top technology in the automobile repair. And modern cars, especially small engines, are thin and wear resistant alloy coatings on the crankshaft bearing and connecting rod bearing bearing bushes. They are not allowed to be scraped and can only be selected according to the corresponding size. If there is no suitable size of the crankshaft bearing, it is necessary to use the method of base hole grinding to obtain the proper fit clearance when necessary. 2. engine water temperature is afraid of high and low. The water temperature is high, and every possible means to find the cause, and the low water temperature is considered normal. In fact, the low temperature of the modern automobile engine is very low, which will make the combustion of mixed gas insufficient, the power is reduced, the fuel consumption is increased, and the lubrication is bad, and it will also cause the excessive emission. The gap between the 3. valves is stronger than the smaller point. In fact, the valve clearance is large, and the valve lift is not enough, which makes the intake volume insufficient or the exhaust is not smooth, which reduces the power of the engine. 4. oil is getting better. It is considered that the engine and oil should not be much less and less easily to burn. In fact, too much oil will do harm to the engine, especially the tilting engine and V engine. It increases the rotational resistance of the crankshaft and connecting rod, and increases the oil splashing to the cylinder wall, resulting in the increase of coke in the combustion chamber. So too much oil will reduce engine power, increase wear and tear, and also cause excessive emissions. The 5. air hub is not lubricated. It is considered that the wheel hub is filled with grease, which can ensure the lubrication of the hub bearing. The empty hub with grease coated on the bearing is not lubricated, and the gap between the center of the hub must be filled with grease. In fact, this not only wastes grease, but also affects the heat dissipation of bearings, which is harmful to the bearing lubrication. The 6. brake is good or bad to see that the wheel has been locked, and the modern car requires the wheels to be unlocked, so the anti lock device is specially installed. In fact, the maximum braking force of the wheel is in the condition of edge rolling before the wheel is locked. Once the wheel is locked, the steering of the car is out of order, the wheel is slippage, and it is easy to fail, so it is not the longer the longer the better. The contact gap between the 7. broken electrical appliances is better than the smaller point. In fact, the contact gap is too large and the contact closure time is short, which reduces the primary side current of the ignition coil and causes the high voltage spark to be weak, thus causing the engine to be difficult to start. 8. the ignition advance angle or injection advance angle is larger than the ignition angle. The deflagration of the engine will cause great damage to the piston, seriously affect its service life and increase the starting resistance of the engine. 9. fastening bolts are rather tight and not loose. As a matter of fact, the bolts of each part of the automobile have corresponding value according to their diameters, pitch and usage. The bolts that can not reach the specified value will be loose, but it is not good, but the blind increase of tightening torque will make the fastened parts deformed, and cause the elongation of the screw, the deformation and even fracture of the thread. 10. car maintenance dismantled and checked. With the improvement of the manufacturing level, the life of modern auto parts has been greatly extended, and the random dismantling is bound to destroy the fit state and shorten the service life of the parts greatly. In today's automobile failure detection technology is becoming more and more perfect today, if there is no obvious failure of components or assemblies, do not generally remove the inspection.