There are some misunderstandings in the use and maintenance of cars, which have been formed in the years of low automobile manufacturing level, backward repair means and lack of testing means. These misunderstandings sometimes seem to be correct, but in fact, it is very harmless, which will cause the vehicle to be damaged and the personal safety is threatened, and the greater may be the hidden danger of the accident, or the decline of vehicle performance, the accelerated wear and tear, the shortened life span and so on. First, if the engine temperature device is dismantled blindly, if the temperature device is dismantled blindly because of the high temperature of the engine, the coolant can only carry on the large circulation, and can not adjust the cooling strength. It is difficult to ensure that the engine works at a better temperature. Instead, the engine often works at low temperature and causes the engine power to decrease and wear and wear. Fast, the fuel consumption is increasing. If the engine thermostat is troubleshooting or replaced, the engine temperature is still high, the other parts of the cooling system should be overhauled and the thermostat should not be removed. Two, engine temperature is not afraid of low, some people think that the engine temperature is not afraid of low. In fact, when the engine temperature is low, the danger is also great. The service life of the engine must be ensured according to the normal temperature required by the vehicle manual. Three, the tighter the pump fan belt is, the better the belt is. The tightness of the belt will not only lengthen or break the belt, shorten the life of the belt, but also cause the deformation and bending of the shaft of the generator and the shaft of the pump and the early damage of the bearing because of the excessive tension. The tightness of the automobile engine fan belt should meet the technical requirements. When the normal belt is assembled, the deflection is 10-15mm. Four. When the engine is heating up at idle speed with idle speed, because of low speed, the oil pump can not press the lubricating oil into all the lubricating surfaces quickly, and the oil pressure is low, so that the engine parts work under dry friction or semi dry friction, and the fuel is bad at low temperature and causes the unburned fuel (mixed gas) to move into the crankshaft. Washing the oil film on the cylinder wall will also accelerate the wear of the machine parts. So, after the engine starts a few seconds, the application is fast idling heating (the modern car is equipped with a fast idle speed device, after the temperature rises, it will automatically adjust to the idle state) to improve the engine lubrication conditions. Five. Bake the oil bottom in the oil bottom in winter with a spray lamp and bake the oil with a spray lamp in winter. It will not only make the additives in the oil change chemical changes, lose the original performance, but also make the oil cementing and the oil bottom deformation and cause the fire easily. The best way is to choose suitable oil according to the local minimum temperature in winter. Where conditions permit, vehicles should be parked in the garage with thermal insulation facilities. The more advanced methods are ultrasonic cleaning and spray cleaning, but the most simple and simple method is physical clearance and chemical cleaning. These two methods can also be used concurrently.