What is the general diagnostic sequence of squeak and noise in the chassis of a car

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Loose chassis generally occurs in older cars, when the car is driving in bad road conditions, the steering wheel will feel unstable, the bottom of the car will also come out of the abnormal sound, usually the old driver can feel the overall a little loose, when encountering such a situation, it means that the chassis may be loose, and the reasons for this situation are divided into several, only by understanding the reasons, can we better prevent this problem from happening.

The first reason is the aging of rubber parts, we all know that the elasticity of rubber is particularly good, which can buffer the friction between parts and reduce noise at the same time. However, this kind of thing has a lifespan, and it will age after a long time, and the elasticity is not as good as before, so the buffering capacity will decrease, resulting in abnormal noise in each part, so it is necessary to check these rubber parts regularly and replace them in time.

The second possibility is the reason for the shock absorber, the main role of this part is to inhibit **, when the car is driving in the dustpan section, it will have an impact with the road surface, and the shock absorber can well ensure the smoothness of the car, if the shock absorber is damaged, there will be a scoop phenomenon, so that the chassis is loose, so usually check the shock absorber, if there is a leakage to repair in time.

The third is the clearance of the parts, that is to say, the ball head may be loose, this part is like the joint of the human body, if the ball head is loose, there will be a large gap between the lever and other connected parts, if the gap is too large, when crossing some dustpan roads, the screws between the subframe and the suspension will be loose, then the chassis will become loose, so usually check these two parts. Thank you.

It can probably be judged from the following aspects:

1. Control whether the rubber sleeve of the arm is broken;

2. Whether the chassis bolts are loose and whether it is caused by serious bottom support;

3. Whether there is abnormal noise during bearing operation can be solved by lubrication;

4. Whether there is leakage in the suspension system;

5. Whether the bottom guard plate is bumped, resulting in the collision between the bottom guard plate and the machine, and the resonance emitted;

6. The front top reduction rubber is damaged or needs lubrication;

7. The rubber sleeve of the balance bar is damaged or needs lubrication.

4. Can the failure of the variable intake manifold system also lead to an increase in fuel consumption?

The variable intake manifold length consists of a transfer valve, a solenoid valve, etc., within the tube. When the engine speed is lower than 4000 rpm, the intake manifold maintains a long channel state, the cross-sectional area is reduced, and the intake inertia pressurization is used to increase the charging capacity and increase the torque. When the engine is higher than 4000 rpm, the valve is opened, the intake manifold maintains a short channel state, the cross-sectional area is reduced, the intake resistance is reduced, the intake volume is increased, and the high power is maintained.

However, the variable intake manifold system can fail (including any part of it) if it remains in a long channel state, resulting in increased fuel consumption and reduced power at high rpm. And sometimes there is no fault code display.

1. The abnormal noise emitted by the vehicle at the beginning is usually a suspension system failure, which may be caused by a loose or damaged engine stand;

2. The abnormal noise emitted by the vehicle when steering may be the fault of the steering system and the suspension system, because the vehicle tilts the vehicle during the steering process, deforms the suspension system, and also participates in the movement;

3. The abnormal noise emitted by the vehicle when driving in good road conditions may be the fault of the braking system components, or it may be caused by the loosening or wear of the braking system components, the brake drum is out of circle or the brake disc plane is uneven;

4. It may also be a problem with the bearing between the vehicle connection and static, if it is a bearing problem, the driver can distinguish it with a little brake, if the vehicle does a uniform motion with a brake sound, it is a problem with the bearing.

Various possible causes of abnormal noise in the chassis of a car.

1. Abnormal sound of disc brakes.

Features: When the vehicle is driving at a low speed on a flat road, it makes an intermittent and irregular "rattling" sound on the axle.

Reason: This is due to the damage, deformation and falling off of the brake shoe support plate, vibration damping spring plate or guide plate of the disc brake, which increases the gap between the brake shoe and the brake caliper support frame, and makes a sound when it hits each other. You can go to the repair station to repair the deformed parts and replace the parts that have fallen off.

Second, the front suspension ball head abnormal sound.

Features: When the vehicle is driving on the undulating road surface in a low-speed gear, the front axle part emits an uninterrupted "click" sound, the worse the road quality, the louder the sound, and the sound intensifies with the increase of speed.

Reason: The gap between the ball head and the ball head seat becomes larger, and the looseness is severe. Because the ball head seat is a sealed structure and cannot be removed, it can only be replaced at the repair station in this case.

Three. Abnormal noise of the front wheel shock absorber.

Features: On flat roads, you can hear the "cooing" of the front of the vehicle, which is intensified when turning sharp corners.

Cause: Vehicles are often driven on bad roads and are not properly maintained, resulting in oil leakage and damage to shock absorbers. Depending on the severity of the damage, it will need to be repaired or replaced.

Fourth, the transmission shaft universal joint abnormal sound.

Features: If the front drive constant velocity joint is faulty, in the vehicle in motion, especially when cornering or accelerating sharply.

Reason: The abnormal sound of the constant velocity gimbal is due to the excessive clearance of the gimbal or the issuance of cards. The main reason for the abnormal sound of the universal cross shaft is that there is no lubrication device or the maintenance is not timely. In this case, you should go to the workshop to apply grease or repair.

1. Distinguish between wheel or tire noise and rear axle noise, tire noise changes with the road surface, but rear axle noise is not. When the speed of the car is below 48kmh, the rear axle noise disappears, while the tire noise continues. The noise of the tires is the same when the car is driving and coasting, but the noise on the rear axle is different.

2. With the discrimination of abnormal noise of automobile wheel hub bearing and rear axle noise, when the car is driving and coasting, when the speed is greater than 48km h, unless the rear wheel axle is seriously damaged, the noise of the rear wheel bearing can rarely be heard under normal circumstances, when the car is coasting or neutral, the cracked rear wheel bearing will produce a "rumbling" sound, and the corroded rear wheel bearing will make a "rustling" sound.

3. The reducer bearing usually produces a harsh "rumble" or "rattle" sound, and the sound beat is stable and changes with the change of vehicle speed. The sound of the front bearing of the bevel driving gear of the reducer is louder when the car is coasting, and the noise of the rear bearing is louder when driving.

4. During the driving of the car, most of the reasons for the abnormal sound of the rear axle gear are caused by poor lubrication, which leads to the grinding of the reducer gear. At low speeds, there is a knocking sound on the rear axle, and when accelerating or decelerating, it makes a particularly dull abnormal sound.

The reasons for the abnormal noise of the general chassis are: 1. Loosening of parts: Causes:

Interaction between two parts as a result of violent impact or pretending to be other equipment; Solution: Repair or replace the relevant parts by shaping and repairing the parts so that the parts no longer interfere. 2. Loose bolts or nuts:

Causes: Bolts are loose due to long-term driving on roads with poor road conditions, or unreasonable disassembly or installation, resulting in bolt damage or insufficient torque; Solution: Tighten the bolts and replace the bolts if necessary.

3. Failure of the universal joint of the transmission shaft: Cause: the dust jacket is damaged and the oil leakage is not repaired in time, resulting in abnormal wear of the small bearing; Solution:

Replace with a new outer (inner) cage or gimbal. 4. Abnormal sound caused by the damage of the ball head suspension bracket: Causes:

Abnormal noise caused by the aging of the loose rubber sleeve of the ball head after long-term use; Solution: Replace with a new ball head or bracket. 5. Abnormal noise of braking system:

Causes: loose brake pads, loose calipers, brake pads, brake discs; Solution: Check whether the brake system is loose, whether the brake pads and brake disc are worn, and if necessary, they need to be replaced.

6. Abnormal sound of wheel bearing: at a certain speed, there will be a "buzzing" sound, but this sound increases with the increase of speed. Reason:

Caused by abnormal wear or ablation of bearings; Solution: Replace the wheel bearing with a new one. 7. Clutch abnormal noise:

When the clutch pedal is pressed, there will be an abnormal sound, and the abnormal sound will disappear when the pedal is released. Reason: Abnormal wear caused by lack of oil in the clutch release bearing; Solution:

Replace the clutch with a new one, and start talking about selling the clutch bearing. 8. Abnormal sound of gearbox: Reason:

Wear of the gears inside the gearbox or lack of transmission oil; Solution: First check whether the transmission oil is sufficient, if it is missing, then try again; If it is normal, the gearbox needs to be disassembled and inspected.

On the issue of abnormal noise of automobiles, it is difficult for ordinary car owners to distinguish which ones are abnormal noises and which ones are reasonable abnormal noises. Only nearly 20% of the vehicles that went to the repair shop to detect abnormal noises really had problems. Models equipped with turbocharged engines are wide and different; Models with engine guards may also make noises due to friction; After some car owners come into contact with different cars, it is likely that due to their lack of understanding of mechanical knowledge, they mistake reasonable abnormal noise as a vehicle failure.

Therefore, learn to distinguish the abnormal noise of the car and avoid wasting time and energy.

Second, the identification method of car noise:

In practice, due to the limitations of working conditions, it is difficult to measure the sound of the car with special instruments, and the sound of the car can only be described and compared with the judgment of the sound in daily life. For example, the "rattle" sound caused by the dry friction of the bearing, and the "click" sound similar to the small hammer hitting the cement floor caused by the excessive valve clearance.

1. Correctly distinguish between normal and abnormal sounds.

The vibration of each mechanism in the work of the car will emit a variety of sounds, but the sound does not mean that the car is faulty, in order to avoid unnecessary disassembly, we must first distinguish between normal sound and abnormal noise. The normal vibration sound of each system component (such as the noise on the surface of the engine), the impact sound of the gear when shifting, the air intake sound and exhaust sound of using gas as the working source, and the gear meshing noise are all normal sounds. Abnormal noise (abnormal noise) can be divided into slight noise, general noise and malignant noise according to the impact on the performance of the car.

Slight noise, such as the flashover sound of high-voltage electric leakage, the slight loose sound of rolling bearings, etc., the general volume is small, the degree of wear of the parts is not large, and there is no significant change for a long time, and this kind of fault can still maintain the normal operation of the car without repair.

3. When diagnosing the abnormal noise of the car, attention should be paid to creating good auscultation conditions and trying to eliminate the interference of other noises, so as not to affect the accuracy of judgment.

It is best to consciously amplify or reduce the sound, that is, use a screw or other metal rod as a stestological instrument to contact the sound part to amplify the sound, or use a single cylinder fire cut-off method to reduce the sound of the sound of the slippery sound, so as to meet the needs of diagnosis. The auscultation site should be kept quiet to minimize human interference.

1. Loosening of parts.

Cause: The two parts interact with each other due to violent impact or pretending to be other equipment.

2. Loose bolts or nuts:

Causes: Long-term driving on roads with poor road conditions, resulting in loose bolts; Unreasonable disassembly or installation causes bolt damage c Insufficient torque.

Solution: Tighten the bolts and replace the bolts if necessary.

3. The universal joint of the transmission shaft is faulty.

Reason: Bohuai dust jacket is damaged and leaked oil and is not repaired in time, resulting in abnormal wear and tear of small bearings.

Solution: Replace with a new outer (inner) cage or universal joint.

4. Abnormal noise caused by ball joint, suspension, bracket damage, ball head, suspension, bracket damage.

Reason: After a long period of use, the ball head is loose and the rubber sleeve is aging and the abnormal sound is caused.

Solution: Replace with a new ball head or bracket.

5. Abnormal noise of braking system:

Causes: a loose brake pads and loose calipers; b Brake pads and brake discs are faulty.

Solution: Check whether the brake system is loose, whether the brake pads and brake disc are worn, and if necessary, they need to be replaced.

6. Abnormal sound of wheel bearings.

At a certain speed, there is a "buzzing" sound, but this sound increases as the speed increases.

Cause: Caused by abnormal wear or ablation of the bearing.

Solution: Replace the wheel bearing with a new one.

7. The clutch of the silver bird is abnormal.

When the clutch pedal is pressed, there will be an abnormal sound, and the abnormal sound will disappear when the pedal is released.

Cause: Clutch release bearing lack of oil, abnormal wear and tear.

Solution: Replace the clutch release bearing with a new one.

Judgment method of abnormal noise in automobile chassis: 1. Distinguish between tire noise and rear axle noise, tire noise is the rear axle noise that changes with the road surface, but not. When the speed of the car is below 48kmh, the rear axle noise disappears, while the tire noise continues.

The noise of the tires is the same when the car is driving and coasting, but the noise on the rear axle is different. 2. With the discrimination of abnormal noise of automobile wheel hub bearing and rear axle noise, when the car is driving and coasting, when the speed is greater than 48km h, unless the rear wheel axle is seriously damaged, the noise of the rear wheel bearing can rarely be heard under normal circumstances, when the car is coasting or neutral, the cracked rear wheel bearing will produce a "rumbling" sound, and the corroded rear wheel bearing will make a "rustling" sound. 3. The reducer bearing usually produces a harsh "rumble" or "rattle" sound, and the sound beat is stable and changes with the change of vehicle speed. The sound of the front bearing of the bevel driving gear of the reducer is louder when the car is coasting, and the noise of the rear bearing is louder when driving.