What are the common car malfunctions? About
1. Black smoke from the exhaust pipe: Fault determination: True fault. Cause analysis: Indicates that the mixture is too thick and the combustion is incomplete. The main reasons are that the car engine is overloaded, the cylinder pressure is insufficient, the engine temperature is too low, the carburetor is improperly adjusted, the air filter element is blocked, individual cylinders do not work and ignition is too late, etc. When eliminating, check whether the choke door is fully opened in time, and repair it if necessary; Look at the main nozzle from the carburetor port after turning off the flame. If there is oil injection or dripping, the oil level of the float chamber is too high, and the main measuring hole should be adjusted to the specified range, tightened or replaced; the air filter is blocked, and it should be cleaned. Unclogged or replaced.
2. The exhaust pipe of the vehicle emits blue smoke: Fault determination: True fault. Reason analysis: It is caused by a large amount of oil entering the cylinder, but it cannot be completely burned. Remove the spark plug to find serious carbon deposits. It is necessary to check whether the oil level of the oil dipstick is too high; whether the gap between the cylinder and the piston is too large; whether the piston ring is installed upside down; whether the intake valve duct is worn or the sealing ring is damaged; whether the cylinder gasket is ablated, etc. If necessary, it should be repaired.
3. White smoke is emitted from the exhaust pipe of the vehicle. It is serious when the car is cold. After the car is hot, white smoke is not emitted: Fault determination: False fault. Reason analysis: This is because the gasoline contains moisture, and the engine is too cold. At this time, the fuel entering the cylinder is not completely burned, resulting in fog points or water vapor to form white smoke. In winter or rainy season, when the car is first started, white smoke can often be seen. It doesn't matter, once the engine temperature rises, the white smoke will disappear. This condition does not need to be overhauled.
4. The engine noise is large. When the vehicle steps on the accelerator pedal in place, there is an abnormal sound of "long. Long", and there is a sense of vibration in the engine compartment. Fault determination: Use type failure. Cause analysis: Lifting the vehicle, you can see that the bottom guard of the engine has bumping marks. If there is an obstacle on the road and it is forced to pass, the engine bottom guard will be bumped. After the bottom guard is deformed, the distance between the bottom guard and the engine oil pan becomes closer. If the distance is too close, when the oil pan and the bottom guard collide during acceleration, it will emit abnormal noise and cause the body to vibrate. Therefore, you must carefully observe the road surface during driving to avoid the phenomenon of dragging the bottom. Treatment method: Remove the bottom guard and flatten it for correction.
5. The steering wheel of the vehicle is always incorrect, sometimes to the left, sometimes to the right, erratic: fault determination: true fault. Reason analysis: This is due to the complete damage of the rubber limit block fixed in the groove of the steering machine. After the new limit block is installed, the fault completely disappears.
6. Every time the air conditioner is turned on, its trend has a very unpleasant smell, which is more serious when the weather is humid: Fault determination: Maintenance type failure. Cause analysis: The refrigeration principle of the air conditioner is to quickly evaporate and absorb heat through the refrigerant, so that the temperature of the air flowing through it drops rapidly. Due to the low temperature of the evaporator and the high temperature of the air, the water molecules in the air will condense into water droplets on the evaporator, and the dust in the air or clothes. Small fluff and other substances on the seat are easy to adhere to the surface of the condenser, resulting in mildew and bacteria will multiply. Such air is inhaled by the human body for a long time, which will affect the health of the driver and the passenger. Therefore, the air conditioning system should regularly replace the air conditioner filter element and clean the air duct.
7. Windshield glass is not clean when it rains lightly: Fault determination: Maintenance failure. Reason analysis: It feels good to use the wiper when it doesn't rain a lot, but when the wiper is started in the next light rain, you will find that the wiper will leave traces of uneven wiping on the glass surface; sometimes it will get stuck on the glass and cause poor line of sight. This situation indicates that the wiper sheet has hardened. The wiper is converted into a one-to-one motion by the connecting rod with the rotational energy of the motor, and this force is transmitted to the wiper arm. When the rubber part of the wiper is not hardened, the wiper will not fit tightly with the glass surface, or the wiper sheet will be damaged, which will cause uneven wiping and form residual dirt. The replacement of the wiper or wiper film surface is very simple. But when replacing, it should be noted that the installation method and length of the wiper are different in different models and years. Some wiper film replacement is very simple. But when replacing, it should be noted that in different models and years, the installation method and length of the wiper are different. Some wipers only need to replace the rubber sheet, while others need to be replaced as a whole.
8. Vehicle noise: fault determination: false fault. Reason analysis: Whether it is a high-end car, a low-end car, an imported car, a domestic car, a new car, or an old car, there are different degrees of noise problems. The noise in the car mainly comes from five aspects: engine noise, wind noise, body resonance, suspension noise, and tire sound. When the vehicle is running, the engine is running at high speed, and the noise is transmitted into the car through the firewall, bottom wall, etc.; the body resonance generated by the car on a bumpy road surface, or the failure of the open windows when driving at high speed, will become noise. Due to the narrow space in the car, the noise cannot be effectively absorbed, and collisions with each other sometimes resonate in the car. During driving, the noise generated by the suspension system of the car and the noise generated by the tires will be transmitted into the car through the chassis. Suspension methods are different. The brands of tires are different. The tire patterns are different. The noise generated by different tire pressures is also different. Different body shapes and different driving speeds also generate different wind noise. Under normal circumstances, the higher the driving speed, the greater the wind noise.
9. The engine temperature is suddenly too high during operation: Fault determination: True fault. Cause analysis: If the car is running, the coolant temperature gauge indicates that it will soon reach the position of 100 ° C, or when the cold car is started, the engine coolant temperature rises rapidly to boiling, and turns to normal after replenishing the coolant, but the engine power drops significantly, indicating that the engine mechanical system is faulty. Most of the causes of such failures are: serious water leakage in the cooling system; the cylinder pad that isolates the water jacket and the cylinder is damaged; the main valve of the thermostat falls off; the fan drive belt is loose or broken; the water pump shaft and the impeller are loose; the fan clutch is not working well.
10. When the car accelerates, the oil pressure indicator light will light up: Fault determination: true. False faults coexist. Reason analysis: There are two situations when the oil light is lit. The so-called real is that the oil pressure is indeed low, so low that the indicator light issues a warning, indicating that the lubrication system is indeed faulty and must be eliminated. The so-called virtual, as suspected, there is no fault in the oil lubrication system, but the oil pressure indicator system has failed, and the indicator light is lit in the wrong place. This kind of fault will not affect the normal operation of the engine, but it should also be found in time to eliminate the root cause. Usually, the possibility of real disease is relatively large, and it should be used as the main idea to judge the fault.
11. The whole vehicle shaking phenomenon occurs when the vehicle is driving at high speed: Fault determination: true fault. Reason analysis: When the vehicle is driving normally to about 96km/h, the whole vehicle shaking phenomenon occurs, and the speed is reduced, and the phenomenon disappears. If it accelerates to about 90km/h, the shaking occurs again, indicating that the car chassis is faulty. The reasons for the failure are: tire dynamic balance misalignment; front and rear suspension. Steering. Transmission and other mechanisms are loose; front wheel alignment. Wheelbase misalignment; half-axle clearance is too large. First, the tire balance misalignment will make the wheel even with the rolling edge jump, which is the main reason for the whole vehicle shaking. Secondly, the suspension mechanism. Steering mechanism. Transmission mechanism is loose. Loose, resulting in the front beam value. The misalignment of the wheelbase of the car and the softness of the leaf spring cause the vehicle to resonate during driving, which induces the whole car to shake. Thirdly, the half-axle clearance is too large, which makes the latter move irregularly during driving, and the wear and tear intensifies, causing the unbalanced rotation mass and causing the whole car to shake. If the above faults are not eliminated in time, it will lead to a vicious circle and cause other faults.
12. When the car turns, the big turn that the steering wheel clearly turns turns turns into a small turn, and the steering wheel clearly turns a small turn but turns into a big turn: Fault determination: true fault. Cause analysis: The former is called understeer, and the latter is called oversteer, indicating that there is a problem with the steering system. When the driver accelerates while the car is steering, the feeling is that the car with understeer performance will travel to the outside side, and the car with oversteer performance will travel to the inside. When the driving radius increases, it is called understeer. When the driving radius decreases, it is called oversteer. There is also a steering phenomenon, which is initially understeer, and then becomes oversteer in the middle, and steers sharply to the inside. This is the most dangerous reversal phenomenon and is prone to accidents. This situation only occurs in individual rear-engine cars.
13. It is difficult to start the engine cold car. After starting, the engine vibrates, and then stabilizes. The engine starts to shake at medium and low speeds, and improves at high speeds. Fault determination: true fault. Cause analysis: It may be a spark plug failure or a premature ignition time. If it is not a spark plug failure, it can be judged that the ignition time is premature. If the ignition time is too early, at the moment when the spark flashes, the piston is far from the top dead center, and the pressure and temperature of the mixture in the cylinder are not high, causing the flame to form slowly, and the propagation speed after the flame is formed is also low. In this process, part of the mixture in the combustion chamber that is far away from the spark plug cannot wait for the spark plug to ignite, and it automatically burns due to the temperature radiation and expansion of the burned mixture, causing deflagration, which causes the engine to shake seriously at medium and low speeds. In the event of the above failure, you should promptly go to the repair shop for repair.
14. The engine is not running smoothly, often accompanied by a "sudden. Sudden" sound. When accelerating, the engine power is insufficient, and from time to time it emits a "Peng. Peng" gunshot sound, and the exhaust pipe emits black smoke. Fault determination: True fault. Cause analysis: It may be that the carburetor and platinum fail or the ignition time is too late. If the ignition time is too late, when the engine piston is very close to the top dead center, the spark plug starts to ignite. The combustion of the mixture is delayed and the combustion is incomplete. When the piston goes down and even when the exhaust valve is opened, the mixture is still burning. The expansion of the combustion chamber volume and the hysteresis expansion of the gas cause the cylinder pressure to be low and the engine power to drop. Partial combustion expansion of the mixture may also return to the carburetor through the intake valve, resulting in a tempering phenomenon and a violent "Peng. Peng "sound, the incomplete combustion mixture emits black smoke from the exhaust pipe. In the event of the above failure, you should go to the repair shop for repair in time.
15. When the car is parked for a long time in winter, it is more difficult to start the engine: Fault determination: false fault. Reason analysis: Due to the low temperature, the gasification rate of the fuel decreases, and the mixture becomes thinner and less combustible, causing difficulty in starting. At the same time, due to the low temperature, the viscosity of the oil increases, and the engine running resistance increases, causing difficulty in starting. In addition, the chemical reaction of the battery electrolyte is slow, resulting in insufficient power output during starting. Insufficient starter power and insufficient ignition voltage make it difficult to start the engine. Therefore, the car should preheat the engine before starting in the cold season. Hot water or steam can be poured into the radiator and water jacket, and the temperature in the water jacket can be conducted to the cylinder wall, so that the fuel entering the cylinder during starting is easy to vaporize, and the temperature of the combustible mixture can be increased to facilitate combustion. The battery can also be preheated as needed to enhance the battery's power, increase the starting current and ignition voltage.
16. The steering wheel swings when the car is empty and heavy, and the swings are more serious when driving on a flat road. Fault determination: true fault. Cause analysis: Generally, it is due to the front beam not meeting the technical standards and the ball head of the horizontal tie rod. The internal matching clearance of the steering machine is worn too much or the steering machine fixing bolts are loose. The steering knuckle pin and bushing are worn too much. The combined torque formed by the looseness caused by the above reasons will push the steering wheel to swing left and right.
17. When the car encounters a fault while driving, it causes the steering wheel to swing, and the swing is more serious when the car is heavy: Fault determination: true fault. Reason analysis: Generally, it is due to uneven wear of the front tires, uneven use of newly replenished tires or pads, and deformation of the steel rim. Because when the wheel rotates faster, the torque that drives the steering wheel to rotate mainly comes from the yaw of the tire or rim. When the swing difference of the tire or rim exceeds 3mm, the yaw torque can drive the steering wheel to swing left and right. You should go to the repair shop to check and replace the tire or rim as appropriate.
18. Driving at high speed on a good road surface, the steering wheel swings when the car is heavy and empty, and the swing is serious when the car is heavy, and the faster the speed, the more serious the swing: Fault determination: true fault. Reason analysis: Generally, the thickness of the brake drum varies due to the loosening of the connecting bolts between the brake drum and the wheel hub, the loosening of the bearing hole of the wheel hub, and the off-center boring of the brake drum, resulting in an unbalanced amount. Because, in the case of high-speed driving, the wheel speed is very fast, and the torque driving the steering wheel swing mainly comes from the rotation uniformity of the brake drum and the wheel hub and its balance amount. Under the action of the unbalanced amount, both the inertia and the forward inclination angle generate the torque driving the steering wheel swing.
19. There is some shaking when loosening the clutch: Fault determination: True fault. Reason analysis: Explain that the clutch fork, release bearing, pressure plate and friction plate are seriously worn, the transfer device has no oil, the front telescopic sleeve of the rear drive shaft and its bearing are seriously worn. Ground black, and the oil seal of the back cover of the transfer device has been burned. There can only be two reasons for the above situation. One is that there is a problem with the positioning of the transmission shafts, resulting in non-parallel shafts; the other is that the gap between the shafts is too large.
20. Unscrew the radiator cover and find that there are always some oil stains floating on the water surface, and find that there is moisture when changing the oil. Fault determination: true fault. Cause analysis: The engine has two major circulation systems, one is the coolant circulation system and the other is the lubricating oil circulation system. The two systems are not connected to each other. If there is oil in the water or water in the oil, it means that there is a problem in one of the two circulation systems. "Oil enters water" and "water enters oil" are two different types of faults. Once the engine is running, the oil pressure is always higher than the cooling water pressure, so the oil can easily enter the cooling water from the cracks in the cylinder block. On the contrary, the cooling water is not easy to enter the oil, so the oil entering the water is an internal leakage phenomenon: a crack occurs in a certain position of the oil channel of the cylinder block, and the oil is "squeezed" into the cooling water channel through the crack gap. Since the oil is lighter than water, you can find the oil slick by unscrewing the radiator cover. The water content of the oil is another problem of another nature. It is due to the rupture of the cylinder liner or other external reasons that the cooling water enters the oil pan and mixes into the oil. Therefore, the "oil enters the water" is due to the fault of the engine body itself, while the "water enters the oil" is mostly caused by the engine parts, and the fault nature is different.
21. The newly bought vehicle engine shakes seriously, and sometimes the fault indicator light flashes occasionally: Fault determination: False fault. Cause analysis: Some new cars have this situation, the vehicle engine shakes seriously, and sometimes the fault indicator light flashes occasionally. Many people suspect that the vehicle has quality problems. In fact, the real reason is that unclean fuel causes pollution or blockage of the fuel supply system. At present, some advanced vehicles are equipped with exhaust emission monitoring systems. Since this control system can detect vehicle exhaust emissions and fuel cleanliness very sensitively, the use of unclean fuel can cause fuel supply, ignition, and emission system pollution, which in turn leads to engine failure indicators lighting and different degrees of engine shake. Therefore, an effective solution is to thoroughly clean the contaminated system, continuously add gasoline with stable performance and add a quantitative oil cleaner to improve the situation.
22. The lifting speed of electric windows is different for each door: Fault determination: false fault. Reason analysis: Generally, some sand and dust enter the glass lifting track, which increases the friction resistance between the glass and the groove, and then produces this result. This is not a big problem, as long as the corresponding cleaning can solve the problem. It is recommended to go to a professional maintenance station for operation. If you want to do it yourself, you should choose a professional rubber cleaner. Because there are many rubber seals around the electric window, if the cleaning agent is not used properly, it will corrode the rubber products and deteriorate the sealing strip. Dry and crack, and then lose the effect, and the sealing performance of the window will decrease.
23. When the automatic transmission car is hung in the D position, the car has slight vibration: Fault determination: False fault. Cause analysis: When the vehicle is ready to start, when the automatic transmission is hung in the D position, under the action of the hydraulic torque converter, the first gear friction plate is engaged to generate a forward driving force. At this time, the brake pedal is pressed to prevent this forward force, causing slight vibration of the car. If the vibration is too large, it may be that the friction plate of the forward gear of the transmission is worn and the transmission needs to be overhauled. It may also be that the engine support or the automatic transmission support pad is damaged, resulting in resonance. The engine is caused by a lack of fire. Therefore, pay attention to the usual vehicle state so that abnormalities can be detected in time.
24. The oil of the engine turns black not long after it has been replaced: Fault judgment: false fault. Cause analysis: There are two main reasons for the blackening. The first is due to the role of the cleaning dispersant, and the second is due to the oxidation of the oil in use. If an oil does not turn black during use, it means that the oil does not play its normal cleaning role at all. The current oil generally contains a cleaning dispersant, which absorbs the carbon deposits generated by combustion and the oxides of the oil, so that it can be replaced when changing the oil, so as to ensure the internal cleanliness of the engine. Therefore, the blackening of the oil just replaced is not necessarily caused by the dirty inside of the engine, as long as the oil is changed according to the specified time. Note: Be sure to change the oil and oil filter (or filter element) on schedule. After using the oil for a period of time, the viscosity of the oil thickens and acidic products are produced. If it is not replaced regularly, it will damage the engine components and affect the normal operation of the engine.
25. The engine oil pressure indicator shows abnormal display: fault determination: true fault. Reason analysis: When the pointer of the gauge shows that the oil pressure is abnormal, it indicates that the engine components are faulty. If the oil gauge pointer shows low pressure or the instrument pointer shows large fluctuations, it may be due to the wear of the oil pump. The filter is blocked by dirt. The oil suction filter is exposed to the oil surface. The oil level is low. The air mixed in the oil circuit and the pressure gauge are faulty. In addition, the viscosity of the lubricating oil is low. The oil circuit seal and lubrication are poor. The lubricating oil undercooling viscosity is too large. Too much lubricating oil sludge deposition can also cause the oil pressure indicator to display abnormally.
26. Excessive engine oil consumption: Fault determination: True failure. Reason analysis: Careful friends will find that lubricating oil also consumes normally when the car is in good condition, but when some cars are in poor condition, the exhaust gas of the car emits blue smoke, which actually means that the consumption of lubricating oil is too large. Generally speaking, the consumption of lubricating oil is nothing more than two situations, entering the combustion chamber to participate in combustion, or oil leakage. The reason why the oil can enter the combustion chamber is mainly because the parts are seriously worn, the fit clearance is too large, or the oil pressure is too high, causing the oil to jump into the combustion chamber. The leakage of oil is mainly due to the hardening and aging of the sealing gasket. The valve is stuck. If it is an old vehicle, there are generally cases where the sealing gasket is not tightly sealed due to aging. When encountering the above situation, it is best for you to go through a professional maintenance center, be determined by a maintenance engineer, and implement effective solutions.
27. After a period of time, part of the engine oil is consumed: Fault determination: false fault. Reason analysis: National standards stipulate that the normal loss of oil for vehicles traveling 10,000 kilometers should be within 1L. Generally, the oil capacity of a car is about 4L. When the oil level reaches the oil gauge line MIN, the oil is missing but 0.5-1 L. If the oil loss of the car within 10,000 kilometers is within 1L, it cannot be considered a fault.
28. The ventilation hole on the crankcase is blocked: fault determination: true fault. Reason analysis: When the engine is working, there will always be a part of combustible gas and exhaust gas entering the crankcase through the gap between the piston ring and the cylinder wall. After the fuel vapor entering the crankcase condenses, the oil will be diluted, and the acidic substances and water vapor in the exhaust gas will erode the parts, causing the oil performance to change, so that the oil gradually loses its efficacy. In addition, the gas entering the crankcase causes the temperature and pressure in the crankcase to rise, causing oil to seep from the oil seal, gasket, etc. Due to the reciprocating motion of the piston, the gas pressure in the crankcase fluctuates, affecting the normal operation of the engine. In severe cases, the oil in the crankcase will run up to the combustion chamber and cylinder head cover, and oil will leak from the filler port or the gap of the oil dipstick. In order to avoid the above conditions, the engine is equipped with a ventilation device to balance the inner and outer air pressure of the crankcase. If the oil burns during use, the oil leaks along the joint surface, the oil deteriorates prematurely and the engine idling is not smooth, etc., the crankcase ventilation device should be checked for effectiveness, and the ventilation holes should be guaranteed to be unblocked. And the negative pressure valve plate cannot be deformed. Adhesion or installation is wrong, the breathing tube cannot be bent or blocked, and the one-way valve cannot be installed upside down.
29. The throttle body and idle motor of the engine are dirty: fault determination: true fault. Reason analysis: At present, the idle speed of the engine of the car is controlled by the idle step motor installed in the throttle body. When the engine is running, due to the air quality and gasoline quality, there will be a lot of dirt on the throttle valve and idle valve of the engine throttle body. When the dirt is serious, the engine will have too low idle speed. Poor stability or no idle speed, and the throttle will be issued when refueling. Therefore, it is recommended to clean the throttle body every time the car travels about 20000km. After cleaning, the engine should be set through the diagnostic instrument to achieve normal working condition.
30. When the vehicle accelerates rapidly, the speed cannot be lifted. Fault determination: true fault. Reason analysis: When the car is running, the car accelerates normally when it accelerates slowly, but the speed cannot be increased immediately when it accelerates sharply, and it is impossible to overtake. The possible reasons are the failure of the fuel supply system of the engine. The oil pressure, fuel injection volume, and ignition time do not meet the specifications, and the spark plug and high-voltage line fail. Actual case: There is a car with the above phenomenon. The engine was idling and rushing, and no abnormality was found. Check the fuel supply system of the engine, and the oil pressure, fuel injection volume, etc. are normal. The reading data stream shows that the fault is in the ignition system. Check that the ignition timing meets the specifications. After changing the spark plug, the fault remains the same. The final inspection confirms that the high-pressure spark is not strong enough at high speed. Measure the resistance value of each cylinder high voltage line with a multimeter high resistance gear, all at 25Ω. Due to the high speed and high load, the engine requires strong ignition energy, and the resistance value of the central high voltage line is too large, resulting in ignition energy attenuation, weak high pressure fire, resulting in weak engine acceleration. After replacing a new set of high voltage lines, troubleshoot.
31. Carburetor car engine hot car is not easy to start: fault determination: true fault. Reason analysis: If the engine hot car state is not easy to start, this is the automatic choke system failure, resulting in choke can not automatically open or not fully open. When the vehicle is running, due to the large opening of the throttle, under the large intake pressure, the air flow impacts the choke off the central axis, so that the choke can be fully open at this time, but at low speed or idle speed of the engine, the throttle opening is very small, so the intake pressure is not large. At this time, the choke can only be half open or the opening is very small. Under the action of the choke valve, the mixture entering the cylinder is thicker. If the engine stops running at this time, the choke valve will close. When the engine is started again, the overly rich mixture will enter the cylinder to wet the spark plug, making it difficult to start the engine. In this case, you can take all the accelerator pedals, fully open the choke valve and throttle valve, turn the starter, and dilute the overly rich mixture by inhaling fresh air to start the engine. When the spark plug is severely flooded, it can be removed to dry, but it is important to go to the repair shop to find out why the choke valve cannot be fully opened.
32. Black smoke coming from the exhaust pipe of the vehicle when driving at high speed: Fault determination: True fault. Cause analysis: Under normal circumstances, black smoke coming from the vehicle at medium and high speed is not noticeable when driving by yourself. However, it can be determined by calculating the fuel consumption. Carburetor engines are mainly caused by the following four reasons: the oil level is too high, causing the mixture to be too rich; the vacuum economizer fails, causing inappropriate enriched mixture; the main air volume pore foam pipe is blocked; the air filter is blocked. The air filter filter filter element should be checked first. If it is blocked, black smoke will be discharged at high speed, and the power and economy will deteriorate. At this time, the air filter element should be replaced. Then check the carburetor. The above operation requires professional personnel to carry out. There is also an overall inspection of the ignition system and engine.
33. In winter, the sunroof of the vehicle cannot be opened: fault determination: false fault. Reason analysis: In winter, vehicles parked outdoors will melt the ice and snow falling around the sunroof due to the high temperature in the car the night before, and after overnight, the overall temperature of the vehicle decreases, and the melted snow water condenses into ice. Therefore, it is easy to freeze the sunroof glass and sealant frame. If the sunroof is forcibly opened, it is easy to damage the sunroof motor and rubber seal strip, so it is necessary to wait for the temperature inside the car to rise to confirm thawing before opening the sunroof. Similarly, when washing the car in winter, even if the hot water car is not completely wiped, the residual moisture on the edge of the sunroof will freeze, so the sunroof should be opened after washing the car to dry the surrounding moisture. In addition, the surface of the sunroof sealing strip has been painted or flocked. In order to avoid freezing, it is best to dry the painted strip with a soft cloth and then apply some talc powder. The flocking treatment strip can be dried, do not stick to oil stains.
34. Heavy and laborious steering: Fault determination: True fault. Reason analysis: The reasons are that the rolling bearings and sliding bearings in various parts of the steering system are too tight, and the bearing lubrication is poor; the ball pins of the steering longitudinal tie rod and the horizontal tie rod are adjusted too tightly or lack oil; the steering shaft and casing are bent, resulting in stagnation; improper adjustment of the front wheel front bundle; bending and deformation of the front axle car or frame. In addition, the steering wheel tire is flat. Inaccurate four-wheel positioning data can also cause heavy steering.
35. The steering wheel of the vehicle is difficult to operate when driving: Fault determination: True fault. Reason analysis: It may be that the front wheel specifications or air pressure on both sides are inconsistent; the rear inclination angle of the front wheel kingpin or the outside inclination angle of the wheel on both sides is not equal; the front wheel hub bearing clearance on both sides is inconsistent; the camber or elasticity of the leaf springs on both sides is inconsistent; the wheelbase difference between the left and right sides is too large; the wheel brake clearance is too small or the brake drum is disrounded, causing one side of the brake to issue a card, causing the brake to drag; the vehicle is loaded unevenly, etc.
36. Vehicle steering "fluttering" when driving: Fault determination: True fault. Reason analysis: Often caused by the front wheel "swinging" while driving, the reasons are: the total successful balance of the front wheel is destroyed due to tire padding or vehicle repair; some parts of the transmission shaft assembly are loose; the dynamic balance of the transmission shaft assembly is destroyed; the shock absorber fails; the stiffness of the leaf spring is inconsistent; the steering system parts are worn and loose; the front wheel is improperly calibrated.
37. It can usually drive normally, but sometimes when stopping slowly, there is a feeling of emergency braking, and there is a sense of dragging when starting; at high speed, the fuel consumption is large, and the speed is limited: Fault determination: true fault. Cause analysis: The fault may be on the brake master pump. Actual case: There is a car that reproduces the above phenomenon, supports the car, disassembles and inspects the brakes, brake sub-pump, caliper guide rail and hand brake pull wire, etc., and no abnormality is found. No abnormality was found in the road test. After a period of time, the above failure reappeared, and it could not be pushed without braking. Touch the two wheel hubs with your hand, and it is obviously overheating. After the connecting bolts of the master pump and the vacuum booster are loosened, the brake is released, and the car can be pushed. Remove the main pump, measure the length of the ejector rod of the booster and the depth of the piston of the main pump with a tool, and find that there is no gap between the two. This makes the oil return of the main pump incomplete, resulting in brake lag. After padding and adjusting the gap between the main pump and the booster, install a re-test car to troubleshoot.
38. There is a deflagration sound in the engine during driving, especially when accelerating: Fault determination: True fault. Reason analysis: The deflagration sound is similar to the loud sound of the valve rod, that is, the "click" sound. Since most of the new engines use hydraulic tappers, there will be no excessive noise of the valve rod gap, which is actually a kind of deflagration sound. This noise is mostly caused by the use of low-grade fuel. To eliminate this fault, high-grade fuel that meets the requirements must be more accurate. This abnormal noise is most obvious on the Cherokee car. If you can't buy fuel that meets the regulations for a while, the ignition timing should be adjusted appropriately.
39. Engine hydraulic tappet sound: fault determination: true fault. Reason analysis: An engine equipped with hydraulic tappet does not need to adjust the valve clearance, but due to the decline of hydraulic tappet function or other factors, sometimes abnormal noise occurs. When the engine is idling, in the middle of the engine. A "click" sound will be heard on the side of the valve hydraulic tappet. The sound rule is not obvious. After increasing the engine speed, the sound is weakened or chaotic, and disappears at high speed. Cold cars are more obvious, and hot cars gradually weaken. If the fire is cut off, the sound still exists. This sound is easy to misjudge, that is, it is mistaken for a metal knocking sound in other parts, so it attracts the attention of readers. The reason for the abnormal sound of the hydraulic tappet is that the plunger is worn and the valve leaks oil. The oil pressure of the supply tappet is insufficient. The plunger and tappet body are blocked by oil pollution. When troubleshooting, parts with serious wear and oil leakage should be replaced. Components with less wear can continue to be used through repair.
40. Vacuum hose has air leakage sound: fault determination: true fault. Reason analysis: In use, due to the aging and loosening of the vacuum hose, falling off and deformation, during idle operation, the upper part of the engine will hear a "hissing" air leakage sound. As the speed increases, the sound gradually disappears, and the sound of the cold engine and the heat engine does not change. At the same time, when the engine is running at idle speed, it is also accompanied by a "chug" sound. Some accessories do not work due to insufficient vacuum. Although the sound is small, there are hidden dangers. The above failure is due to the loosening of the vacuum hose. After falling off, a vacuum is generated due to the operation of the engine, and there is a large suction at the vacuum hose joint, resulting in the sound of airflow. The way to eliminate this fault is relatively simple, check each vacuum hose. Is there any aging deformation, cracking or falling off at the pipe joint? If there is any damage, a new part should be replaced.
