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 technology and new technology, the design and manufacturing level of automobile has been greatly improved, the detection and diagnosis technology of automobile failure is becoming mature, and the 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. The main performance of the misunderstanding is as follows: 1. 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 2. valve clearance is larger than the smaller one. 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. 3. 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 4. 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. 5. the contact gap of the breaker is larger than that of the small point. In fact, the contact gap is too large and the closing time of the contact 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. 6. 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. 7. when the car is maintained, it will be relieved if it is opened 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 it is not found that the components or assembly has obvious faults, generally do not disassemble.