1. Grease the cylinder head gasket

Some mechanics install cylinder pads, like to apply a layer of grease on the cylinder pad, think it can increase the engine's sealing. As everyone knows, this is not only useless, but harmful. It is well-known that the cylinder head gasket is an important sealing material between the engine cylinder block and the cylinder head. It not only requires strict sealing of the high-temperature and high-pressure gas generated in the cylinder, but also must be sealed with a certain pressure and flow rate Cooling water and oil, thus requiring the disassembly cylinder gasket, pay special attention to its sealing quality.

If grease is applied to the cylinder head gasket, part of the grease will be squeezed into the cylinder water channel and oil passage when the cylinder head bolts are tightened. The grease remaining in the cylinder head gasket will flow partly due to the high temperature when working in the cylinder head Cylinder combustion, the other part will be burning coke stored in the cylinder and the cylinder cover the combination of the surface, under the action of high pressure and high temperature, the cylinder pad can easily breakdown or burn through, resulting in engine leakage. Therefore, do not apply grease when installing the cylinder head gasket.

2. Diesel car using gasoline engine oil

Oil has a gasoline engine oil and diesel engine oil points. Gasoline engines and diesel engines, although working under the conditions of high temperature, high pressure, high speed and high load, still have a big difference between the two. Diesel compression ratio is more than 2 times the gasoline engine, the main parts are subject to high temperature and pressure impact than the gasoline engine is much larger, so some parts of the production of different materials. For example, gasoline engine main bearing and connecting rod bearing bushings can be made of soft and corrosion-resistant babbitt, while diesel bearing bushings must be made of high-performance materials such as lead bronze or lead alloy. However, the corrosion resistance of these materials Poor performance.

To this end in the diesel engine oil refining process, to add more anti-corrosion agent, so that the use can be generated in the bearing surface layer of protective film to reduce the corrosion of bearings and improve its wear resistance. Since gasoline engine oil does not have such an antiseptic, if it is added to a diesel engine, the bearing pad is prone to spots, hemp pits or even peeling flakes during use, and the oil will quickly become dirty and cause the burning paddle to hold the shaft Accident happened. In addition, the sulfur content of diesel fuel than gasoline, this harmful substances in the combustion process will form sulfuric acid or sulfurous acid, together with the high temperature and high pressure exhaust gas fleeing into the oil pan, accelerate the oxidation and deterioration of oil, so the diesel engine oil refining Need to add some anti-oxidation additives in the process of making the oil alkaline. If the sour gas fleeing, can play a role in neutralization, will not cause excessive oxidation of oil deterioration. The gasoline engine oil is not add this additive, because it was neutral, if it is used in diesel engines, due to the acid gas corrosion soon deteriorate failure. So do not use diesel engine oil filling diesel engine.

3. Domestic car blind use of imported oil

Some owners think that imported oil must be better than domestic oil, so imported oil is used on domestic cars, especially on new cars. As everyone knows, this is often outweigh the benefits, there will be many drawbacks. For example, the majority of imported oil viscosity is low, can not meet the domestic car oil viscosity requirements. Coupled with a variety of domestic engine parts with thermal expansion coefficient and the gap with the imported car, Suzhou, and most of the domestic car engine lubricating oil device is not installed, if the blind use of imported oil, due to the engine at normal operating temperature Excessive oil so that the oil pressure is too low, or even less than the provisions of the working pressure, can not meet the needs of normal lubrication, the engine wear and tear worse.

4. Assembly pump without filling oil

In the repair of the oil pump mounted on the car, if not to the pump gear room filled with oil, will make the oil pump does not pump oil, causing the accident such as burning tiles. Because, gear oil pump is relying on the gear and the housing wall with a smaller clearance, and the gear between the correct fit gap to generate suction. If the oil pump assembly or cleaning the pump after the gear chamber is not filled with oil, the oil pump can not produce enough suction. For a certain wear gear pump, the above phenomenon is more obvious. Therefore, do not forget to fill the gearbox with oil when installing the pump.

Black oil is oil deterioration

Engine oil is working under harsh high temperature conditions, easily oxidative deterioration, produce acidic substances and stacked into polymer deposits, resulting in damage to lubrication. In addition, the combustion exhaust emissions into the crankcase will also promote oil oxidation deterioration. Therefore, the use of a certain period of time, the oil will usually blackening deterioration, loss of its proper lubrication. However, with the continuous improvement of the quality of lubricating oil, especially the popularization and use of thickening oil, black oil does not necessarily mean deterioration of oil. This is because the decontamination dispersant in the thickening oil disperses the sediment on the work piece in the oil, making the oil color black. Whether deterioration, the indicators should be tested, the implementation of regular oil by mass, reducing unnecessary waste. Such as adding YYl02 engine protection agent oil, use a certain time, the same will be black. Therefore, oil black is not equal to the deterioration of oil.

6. blindly choose the oil

Lubricating oil plays the role of lubrication, cooling, cleaning and sealing. The quality of lubricants is directly related to the length of the engine life, so do not blindly choose the engine oil. New car on the very strict requirements of lubricants, choose what lubricating oil, when to replace, how to replace, etc. should be in accordance with the provisions of the manufacturers.

Engine oil selection, it is necessary to pay attention to quality levels, but also pay attention to the viscosity grade. First, you should press the compression ratio, displacement and other performance level of choice; and then according to temperature, load viscosity level selection. In the selection of oil quality should not be high rather low. Good quality oil can ensure good engine lubrication, reduce wear and tear, extend engine life, extend the oil change intervals, reduce the frequency and difficulty of maintenance and repair. In the choice of oil viscosity, in addition to temperature conditions, should ensure that the engine lubrication and sealing conditions, try to use low viscosity oil, in order to save fuel.

7. Use multi-viscosity lubricant is good

Multi-viscosity lubricants (also known as multi-grade lubricants) have the properties of light oils at low temperatures and heavy oils at high temperatures. Where multistage oils are recommended, a multi-grade oil can be substituted A variety of single-stage oil. Although multi-grade oils are available for very cold and warm seasons and heavy-duty engine oils, especially those for diesel engines that are not difficult to start up in cold weather, single-viscosity lubricants are generally recommended for lubricating and prolonging the engine The service life of the engine. Therefore, do not think that using a multi-viscosity lubricant is good.

8. Mix engine oil

All kinds of lubricants, the base oil in addition to the viscosity of the same level of the rest are the same, the only difference is that the variety and quantity of its ingredients. Therefore, according to the general composition of the ingredients and the number of varieties to divide the lubricant varieties and quality levels. Lubricants of different types of additives can not be mixed, otherwise it may make the additives in the oil chemical reaction, damage the lubricating oil should have the effect. With the continuous improvement of additives and their formulations, some universal oils have been developed and manufactured. Such as gasoline engines and diesel engines with QE / CC, QF / CD and other lubricants. They are common across the indicated levels. Therefore, the lubricant can be mixed, according to the requirements of the manual, the name of the control oil, grades, grades, a reasonable choice of use level and the appropriate grade, can not blindly with the risk of use, but can not be mixed.

9. Lubricant is added only do not change

Many owners only pay attention to check the amount of oil lubrication, and according to the standard to add, and not pay attention to check the quality of oil, ignoring the change has been deterioration of oil, resulting in some of the engine's moving parts are always poor Lubrication environment in operation, thus accelerating the lubrication of the wear parts. Therefore, in general, when the car is driving 3500 ~ 5000km, you should change the engine's lubricating oil.

10. Do not add more lubricant

The dangers of too little engine oil are well known to all. Therefore, some car owners fear scarcity of oil, think more lubricants are better than less good, therefore, often do not follow the provisions of the oil, so that more than oil standards. In fact, there are many hazards lubricating oil:

⑴ car crankshaft agitation, so that oil foam deterioration, increasing the crankshaft rotation resistance, it will not only increase the engine fuel consumption, but also reduce the engine power.

⑵ due to oil from the cylinder wall to the combustion chamber increased combustion, so that oil consumption increased.

Accelerate the formation of combustion chamber coke, the engine easy to produce deflagration.

Therefore, the engine oil rather than more mistakenly, the general oil level should be maintained slightly lower than the dipstick on the appropriate scale, the oil level will be counterproductive.

11. The higher the viscosity of the lubricant the better

To prevent wear on the contact surfaces between moving parts, the lubricant must have sufficient viscosity to form an oil film between moving parts at all operating temperatures. However, the viscosity of lubricating oil shall not be higher than the extent that affects engine start-up, and the friction generated under continuous operation is required to be small. The use of excessive viscosity of the lubricant will increase the wear parts, because:

⑴ engine oil viscosity is too large, slow flow, slow flow, high oil pressure, but the oil through the small, can not be added to the friction surface.

⑵ due to the viscosity of lubricating oil, the friction between the parts friction surface increases, to overcome the increased friction, to consume more fuel, but also reduces the engine's output power.

⑶ lubricating oil viscosity, oil circulation rate will be slow, the cooling and cooling effect is poor, easy to overheat the engine.

⑷ due to slow lubricating oil circulation, the number of times through the oil filter is small, it is difficult to timely wear down the metal debris, carbon particles, dust from the friction surface cleaning out.

Therefore, do not use too much viscosity of the engine oil, but can not think of the bigger the better viscosity. Under the conditions of ensuring lubrication, according to the temperature range of use, as far as possible the choice of low viscosity lubricant. However, the wear has been more serious, the gap has been relatively large engine, may be appropriate to use a slightly larger viscosity lubricant.

12. Universal joint cross-axis filling grease

In the general vehicle maintenance manual are clearly stipulated: the transmission shaft telescopic sets of key teeth and the middle bearing using calcium-based grease, the needle bearings of the cross shaft and the middle axle of the axle drive axle drive shaft gear oil. However, in actual work, some repairers mistakenly lubricated the cross-shaft needle bearings with calcium-based grease because of no filling equipment, causing a large number of cross bearings to be prematurely damaged. As the universal joint cross-shaft gear oil filling mouth is a very common butter mouth, often giving rise to a misunderstanding, in fact, grease is less than the filling needle roller bearings. Because the butter viscosity, when the grease gun through the nozzle to the cross shaft lumen grease, the grease into the narrow tank sump oil resistance, this time the grease pressure will open the nozzle opposite the pressure relief valve and Spill, which makes the mechanic mistakenly believe that the bearing has been filled with oil, in fact, not only can not enter the needle roller, that is, to reach the cross-neck end face is more difficult. Therefore, it should be changed with grease instead of gear oil to lubricate the universal joint cross the wrong way, but should gear oil pressure gun filled gear oil.

13. Hub bearing grease as possible

Some owners of wheel hub bearings in the maintenance and the cavity filled with grease, and that the more the better, but it is not. Filling the hub cavity with grease will cause most of the grease to be thrown into the hub cavity, not only to the bearings, but to the brake shoes in the brake drum, causing the brake to malfunction, Rolling resistance increases, causing hubs to overheat and causing unnecessary waste. Therefore, simply coat the hub cavity with a thin layer of grease. Not only ensure the lubrication of key parts, but also easy to cool the wheels cooling, while saving a lot of grease.

14. Grease the grease by adding lubricant

Some mechanics use grease in winter, like to add the original grease grease to dilute. This is wrong. Because the structure of the grease is a colloidal structure composed of thickener and base oil, thickener to form a structure network, the base oil (usually ordinary lubricants) adsorbed in the network to form a stable structural system, will thicken The agent and base oil will not separate. If the fat after adding lubricating oil, although after mixing, but not evenly dispersed in the network, the use of very easy to separate out the loss, is not conducive to lubrication. Such as the need to use a small winter grease consistency, you can use a small number of No. 1 or No. 2 calcium-based grease.

15. Old and new grease mixed use

New greases and old greases can not be mixed even with the same type. Because, the old grease contains a lot of organic acids and impurities, if mixed with new grease will accelerate its oxidative deterioration. Therefore, when changing the grease, be sure to clean the old grease on the parts before re-adding new grease.

16. Fill the leaf spring with grease

Some repair personnel in the maintenance, when fitted with leaf springs, in order to prevent the wear of the steel, the assembly when the filling of grease. In fact, this is not the wrong way to meet the technical requirements. As the grease is easily squeezed out from the steel plate, and easy adhesion of dust, the leaf spring will quickly rust and demolition, reducing life expectancy 40%.

Care or combination of leaf springs should be coated with graphite calcium-based grease, graphite calcium-based grease is calcium-based grease by adding 10% flake graphite made. Graphite itself is a good lubricant, its pressure resistance is good, driving in the car, especially in rough roads, the steel has a strong vibration and friction, the use of calcium-based graphite grease, due to its resistance Pressure is good, not easy to squeeze out from the steel plate, can play a long-term lubrication and protection, extend the life of leaf springs.

17. Grease the tire nuts and bolts

In order to easily tighten the nut and prevent corrosion, many owners and mechanics oiled the tire nuts and bolts. In fact it is a mistake. Because, according to the mechanical principle of knowledge, tighten the nut after the thread, between the threads have a self-locking feature. This is because the thread helix angle is less than the equivalent friction angle between the threads. In a given bolted connection, the helix angle is a constant value, while the equivalent friction angle varies with the friction between the threads. Obviously, the equivalent friction angle between the threads decreases after the oil is applied, and the self-locking performance of the bolt connection becomes worse. Therefore, do not apply grease or oil on the tires' bolts and nuts. In doing so, the nut would be loosened and the tire ran away, causing serious accidents.

18. Start bearing grease

Starter bearings are generally self-lubricating bearings or porous oil bearing alloy, is the use of metal powder (iron or copper powder) by mixing, pressing, sintering molding, immersed in a certain temperature lubricant made of friction-reducing alloy material. It is mainly used for refueling difficulties, light-load high-speed or low-speed load and the need for frequent commutation occasion, according to the composition of the material into iron and graphite graphite and bronze - two categories. Starter maintenance, do not use gasoline cleaning bearings, so as not to dilute the oil, it should be used to clean the cloth or cotton, but should not add grease, because the bearing with the gap is relatively small, grease in the bearings could not survive, throw out After falling on the brush and commutator will cause the starter weakness, serious will lead to commutator ablation. However, a few drops of GL-3 85/90 gear oil can be applied to the bearings. After driving 50000 km, the application of gasoline cleaning bearings, and then placed in about 120 ℃ GL-3 gear oil immersion 1h, the use of better.

19. Burnout lubricator clutch separation