The main reasons for abnormal noises in cars: 1. Abnormal noise from the body 2. Abnormal noise from the suspension 3. Abnormal noise from the engine compartment;
Abnormal noise from the body:
This problem is usually caused by insufficient rigidity of the body, which causes the vehicle to to deform while driving. The door and frame Friction or shaking, or friction between steel plates caused by desoldering in some places, etc. Sticking strips on doors and windows or rubber padding on friction parts can reduce or eliminate abnormal noises, but treating the symptoms does. does not cure the root cause, and some cars abnormal noise may also occur if the vehicle body parts are not properly fixed. This can usually be fixed by tightening the screws.
NoiseAbnormal suspension t:
When encountering bumps, there will be a “dong dong” or “click” sound near the four wheels, which is probably due to the shock absorption. If it is caused by engine problems or loose suspension parts, please go to a regular repair shop for careful inspection, because suspension parts are not only related to driving comfort, but also to the driving safety, which should not be underestimated. .
Abnormal noises in the engine compartment:
There is a greater possibility of abnormal noises here. The belt howl is harsh, which is usually caused by. belt slippage, if there is a dry rubbing sound of metal parts on the outside when the engine is running, this is usually a sign that the bearings of the generator, water pump and steering pump assisted are enddamaged. air leak when the engine is running, it may be that the exhaust system is blocked, the suction pipe is leaking, or if it is broken, it is worth remembering that if it is a abnormal noise in the engine, the car owner will most likely You will not be able to solve it and it is better to send it to the factory for repair.
The lightest point of the tire:
I believe that most car owners do not know the lightest point of the tire. As a rubber product, the weight distribution of tires cannot be completely uniform. So manufacturers will mark the lightest point on the tire, and that lightest point usually corresponds to the valve on the rim. Since the valve is installed on the contour, the mass is greatest there and the lightest points of the two tires can play a balancing role in relation to the heaviest point on the contour.The lightest point of the tire is usually marked with a dot **. The lightest point of the tire may also correspond to the weight added during dynamic balancing to achieve a balancing effect.
What causes abnormal noise in car engines?
1. Abnormal noise in the gearbox If the car makes an abnormal noise while idling, the abnormal noise disappears. once the clutch is depressed, this indicates that the source of the abnormal noise is caused by a gearbox malfunction. Abnormal noise in the gearbox is usually caused by worn bearings or gears. When the car is refueling while driving, you may hear noises coming from the chassis. The gear makes a “click” sound. If the bearing fails, it will make a “rusting” sound. In severe cases, it will turn into a “popping” or “squeaking” sound. Solution: There are many partsn the gearbox and the causes of noise are also complex. Therefore, regardless of the abnormal noise, it should be repaired in time (change).The gearbox requires high maintenance, so it should be inspected frequently and the oil should be changed frequently). 2. Abnormal noises in the engine compartment. It is normal for the motor to vibrate and make noises, but there are also special situations, such as the screeching noise of the belt, which is usually caused by belt slippage. , the high-pitched sound of dry friction of metal parts is usually caused by belt slippage, which damages the bearings of the generator, water pump and power steering pump. Solution: If it is an air leaking sound when the engine is running, it may be the result of a blocked exhaust system, leaking or ruptured vacuum tube . If there are abnormal noises in theengine, this is generally a major fault. It is best if the car owner sends it to the factory for repair as soon as possible. 3. Abnormal noise coming from the steering wheel. If there is an abnormal noise when the steering wheel turns left and right, it can basically be concluded that it is caused by an abnormality in the steering gear. Among them, friction enters. The steering stem and ball joint rubber sleeve are common due to aging. In addition, abnormal noise may also be caused by oil leakage from the steering gear jacket, insufficient tightening of the power assist belt, or aging. Solution: Go to a regular repair shop or 4S point to replace the corresponding parts. 4. Abnormal suspension noise The suspension system maintains continuous operation while driving. The rubber bushings between the shock absorbers and each connecting rodwill inevitably wear out. When the bushings age or fall off, abnormal noise will be heard if the shock absorber is. broken, there will be a “dong dong” or “click” sound on the bumpy road. Solution: Go to a repair shop or 4S workshop to have the parts replaced by a specialized technician. If this occurs, it must be resolved as quickly as possible. It is best to strengthen inspections during daily maintenance to avoid the occurrence of abnormal noises. 5. Abnormal tire noise Abnormal noise caused by tires is generally tire noise. If a “popping” occurs, the tread may be mixed with small stones or nails. If it is a faint "pop" noise, it is likely due to tire tread deformation, bagging, heavy wear, or insufficient air pressure. If the tire buzzes and the car bodyshakes considerably or even moves in the same direction, this must be the case. be a burst tire. Solution: If you find that the tread is mixed with small stones, you can remove the small stones from the gaps yourself. If there are other problems, you can only replace the tires with new ones. 6. Abnormal brake noise If there is a "squealing" sound when applying the brakes, it is mainly due to excessive wear of the brake pads, resulting in excessive clearances. Of course, improper use or deformation of the brake disc material, as well as unqualified hardness, porosity, friction characteristics and compression characteristics of the brake pads may cause abnormal noise. Solution: Abnormal brake noise can usually be resolved by replacing the brake pads. If the brake disc is damaged, it must also be replaced. When replacingcement, pay attention to the model and other problems, otherwise abnormal noise will always occur if this occurs. does not match. 7. Abnormal noise from the body Abnormal noise from the body is common. Generally, this is due to the fact that the rigidity of the body is not sufficient. Long-term intense driving or prolonged walking on bumpy roads will wear out the steel chassis. of the car body is slightly deformed. The most direct impact is that the condition of the door and the car is inconsistent. Normal impact or friction, or abnormal friction in some welding or screw parts, can also cause abnormal noise. Some cars have more wind noise. To some extent this has to do with the shape of the car. Solution: These abnormal noises are not terrible and will not have a big impact on the overall performance of the vehicle,but it is difficult to manage and difficult to cure. The only way is to add rubber pads or sponges to abnormal friction or impact parts. 8. Abnormal noises in the car Abnormal noises in the car are common, and there are many places where abnormal noises occur, such as panel seams, door panel seams, armrest boxes, buckles seat belt, etc. This situation is usually caused by parts. are not installed securely or are loose. These are common abnormal noises. For safety reasons, it is recommended to go to the 4S store to check
1. Characteristic Analysis of Abnormal Engine Noise
Abnormal engine noise is often related to engine speed, load, temperature and duty cycle. By analyzing the characteristics of abnormal noise, its changing rules can be found.
(1) Lhe relationship between abnormal noise and engine speed
The existence of the most common abnormal noises in engines depends on the condition of the engine speed.
① Abnormal noise only exists at idle or low speed. The reasons for the noise include: too much clearance between the piston and the cylinder wall; too tight mounting of the piston pin or too tight mounting of the connecting rod bearing too much clearance between the pusher and its valve guide hole; cam profile; sometimes the starter latch is loose and the pulley is damaged (squealing visible when changing speeds).
②The sound is chaotic when maintaining a certain speed, and short-term sounds are emitted one after another during rapid deceleration. The reasons for the noise are: the camshaft timing gear is cracked or its fixing nut is loose; the crankshaft is broken; the axial play of the camshafts is too large or its ring is loose;
③ Abnormal noise occurs when the engine accelerates quickly, and the sound still exists when the engine runs at high speed. The reasons for the noise are: the connecting rod bearing is loose, the bushing is burned, or the size does not match and rotates; the crankshaft bearing is loose or the bushing is burned; broken.
(2) The relationship between abnormal noise and load
Many abnormal noises on the motor are obviously related to their load. When diagnosing, the method of unloading the cylinders one by one can be used. be used for testing. Generally use the single or double cylinder ignition method to relieve the load on one or two cylinders to identify the relationship between abnormal noise and load.
① The fire in a certain cylinder is cut off and the abnormal noise disappears or is reduced. The reasons for this noise are: piston knockingon the cylinder; loose connecting rod bearing; leaking broken piston pin;
② If the fire in a certain cylinder is cut off, the sound will increase or there will be no sound at that time. The reasons for the noise are: the copper sleeve of the piston pin is loose; the conicity of the piston skirt is too great; the connecting rod bearing cover mounting bolts are too loose; or the connecting rod bearing is too loose; the alloy melted; The steering wheel mounting bolts are too loose.
③The abnormal sound of two adjacent cylinders cutting the fire is reduced or disappears. The reasons for the noise are: a loose crankshaft bearing.
(3) The relationship between abnormal sound and temperature
① The sound is emitted at low temperature. As the temperature increases, the sound decreases or even disappears. The reasons for the noise are: the gap between the piston and the cylinder wall is too large; the piston is notas aligned due to the depth and width of the main bearing oil groove; engine oil pressure is low and lubrication is poor; .
② There is a sound when the temperature increases, and the sound decreases or disappears when the temperature drops. The reasons for this noise include: premature ignition caused by overheating of the piston skirt ellipse;The long and short axes of the circle are in opposite directions; the ovality of the piston is small and the gap between the piston and the cylinder wall is too small; the piston is deformed and the gaps between the piston rings are too small; .
(4) The relationship between abnormal noise and motor duty cycle
Abnormal motor noise faults are often obviously related to motor duty cycle, especially to the crank rod mechanism and valve system. the abnormal noise of the mechanism is linked to the cycle of twork. For a four-stroke engine, any noise caused by the crank rod mechanism is emitted twice once when the engine is operating; all sounds caused by the valve mechanism are emitted once when the engine is running;
① The causes of abnormal noise caused by the crank-connecting rod mechanism include: the piston knocks against the cylinder wall; knocking noise from the piston pin and cylinder head; is too loose; the piston ring leaks gas.
② The causes of abnormal noise caused by the valve mechanism include: excessive valve clearance; excessive clearance between the lifter and its guide hole; excessive clearance between the valve stem and its guide; valve spring; The camshaft timing gear is broken radially; the valve seat ring is loose; the valve is stuck and cannot be closed.
③If the abnormal sound has nothing to do withc the work cycle, you must pay attention to the area where it emits the sound. Usually, the noise caused by the gap which has nothing to do with the duty cycle is mainly a fault in the engine accessories; If there is a continuous metallic friction noise coming from the machine parts that has nothing to do with the work cycle, this may indicate that some rotating parts are defective.
(5) The relationship between abnormal noise and engine parts
When abnormal noise occurs in the engine, it will inevitably produce a certain degree of vibration depending on the characteristics and location thereof. vibration, this can help diagnose the occurrence of an abnormal noise reason.