When operating a car with front- or all-wheel drive, the driver may hear a crunching sound when turning the steering wheel to the right or left. Often in this case the CV joint (constant velocity joint or just a grenade) crunches. The sound is characteristic and resembles a booming crack.
It is important to accurately determine:
- which CV joint crunches;
- the severity of the failure;
- Is it possible to get to the service station on your own?
The fact is that on each side there is an internal CV joint, as well as an external CV joint. For diagnosis, it is necessary to separately take into account some features and nuances. Read more in our article.
CV joint: what is it and how does it work
CV joint (constant velocity joint) is a part that transmits torque between axle shafts, while the angle between the axle shafts is constantly changing. CV joints are actively used in cars with front-wheel drive and all-wheel drive.
On the front axle the following are used:
- internal CV joint (internal CV joint);
- outer CV joint (outer grenade);
The inner CV joint is responsible for transmitting rotation from the gearbox to the shaft, while the outer joint transmits rotation from the inner one to the wheel. The use of these elements allows you to transmit torque and turn the drive wheels of the car.
Causes of crunching noise when turning the steering wheel
For example, if the steering wheel crunches when turning, the source of the crunch may be the loosening of the clamp screw connecting the steering shaft to the steering rack.
Thus, in extreme positions, the steering shaft splines disengaged (slipped) with the rack teeth, thereby causing a knocking sound.
Why does the grenade crunch?
In general, the constant velocity joint is a fairly reliable part. Natural wear and tear occurs over long runs (about 150-200 thousand km or more). However, in some cases, a part may fail earlier for certain reasons.
In this case, the main sign of problems with the joint is a characteristic cracking sound (often the CV joint crunches when turning). The crunch of a grenade can also be heard when accelerating a car (especially pronounced with the wheels turned out).
The main causes of CV joint crunching:
- operating a vehicle in difficult conditions (off-road, falling into potholes at high speeds, towing heavy trailers, transporting goods, etc.).
- aggressive driving, sudden acceleration and emergency braking (especially with the wheels turned out), taking sharp turns at high speed, etc.
- rupture of the CV boot, moisture, dirt and dust entering the mechanism (CV joint lubricant accumulates particles and begins to work like an abrasive, destroying the part). By the way, the vast majority of problems with CV joints are associated with damage to the boot;
To understand which CV joint makes a crunching sound when you turn the steering wheel, you need to carry out diagnostics. At the same time, it is not particularly difficult to quickly determine which CV joint is crunching. As part of the inspection, you should pay attention to some features.
- Crunching and squeaking noises are usually produced by the external grenade. You can check the CV joint by turning the wheels and starting active acceleration. As a rule, a not particularly strong crunch when turning will become louder. You should also pay attention to the steering wheel. If vibrations and slight jolts are felt on the steering wheel, this will also indicate problems with the outer joints.
- The inner CV joint usually does not crunch, but slightly taps when driving with the wheels evenly aligned in a straight line. In addition to driving on a flat road, when you hit potholes, the knocking intensifies. The fact is that the load on the inner CV joint is stronger depending on the depth of the hole under the wheels.
Grinding, as well as squeaking (the steering wheel turns both when driving and when standing still)
A grinding/creaking sound that is felt when the steering wheel is turned in different directions. This noise occurs due to wear on the suspension joints or steering joints. Similar to the previous point, here you will need to diagnose the suspension components or steering system, replacing worn parts, if necessary.
However, the most common reason for such a sound is the lack of lubrication in the steering tips (as well as their severe wear).
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Sometimes such a squeak can even be accompanied by a crunching sound, regardless of whether the car is moving or standing still. In this case, the culprits are the lower ball joints (sometimes the shock strut bearings). The first option is also accompanied by play in the steering wheel when the car is suspended.
When is a car's CV joint checked?
If the CV joint crunches, many drivers are interested in how long they can drive the car before repairing such a breakdown. In other words, how long can you drive if the CV joint crunches? There are several reasons why repairs are delayed:
- Constant velocity joints on some cars can be quite expensive.
- the crunching and knocking may not be strong, etc.;
First of all, the ability to operate the car depends on the severity of the breakdown. The more worn out the CV joint is, the sooner it needs to be replaced. In this case, knocking and crunching are indicators indicating the need for replacement.
For example, if the crunch is strong, it is better to change the joint immediately. The fact is that if the unit is completely broken (jamming, cracking of the body or balls falling out, etc.), you can get serious problems with other units, units and elements.
In turn, you can try to eliminate the symptoms of a malfunction at the initial stage using a maintenance method (lubricating the CV joint and replacing the boots). If there is no result, then you should prepare for the fact that with increased noise, knocking and crunching, the part will need to be changed. This can happen after 500-1000 km. after the first symptoms appear, or later.
At the same time, experts still do not recommend operating the car and subjecting the car to loads in the presence of such faults. This means that you can drive with a partially faulty CV joint for some time, however, the part should be replaced at the first opportunity and not delay the repair. If the signs of failure are serious (extreme noise and crunching), you should stop using it and replace the hinges.
How to check the outer CV joint
Having identified characteristic signs of a malfunction, an additional check of the CV joint is necessary. If you need to check the outer CV joint, there are some things to consider. The part is attached to the internal hinge through the axle shaft on one side, and attached to the hub on the other.
Considering that the hinge is a separator with balls, if the ball mechanism is damaged, a crunching sound appears. The case is also protected on top by a dust cover. If the boot is torn, moisture, dirt and dust get inside the CV joint and damage it.
In order to check the outer CV joint, you need to drive on a flat road, turning the wheels in one direction and the other until they stop. In the extreme positions of the steering wheel, you must press the gas. If the crunching intensifies, then the external grenade is faulty. In this case, a crunching sound when turning left will indicate that the CV joint on the right “passenger” side is faulty. If the sound appears in a right turn, in this case the left CV joint (on the driver’s side) crunches.
Checking the internal hinge
As for the inner CV joint, this element is structurally similar to a glass (there is an outer housing with bearings that move in three planes). The shaft is inserted into the gearbox, while the tripod with bearings is fixed to the axle shaft.
The design of the inner CV joint is extremely simple; the joint fails much less often than the outer one. However, the lack of lubrication in the inner CV joint and a torn boot can damage even such a reliable mechanism.
We also recommend reading the article on how to replace ball joints with your own hands. From this article you will learn about the features of replacing ball joints, as well as how to change ball joints correctly and what needs to be taken into account if such a replacement is performed.
To check internal grenades, you need to select a section of the road where there are holes and uneven spots. The main symptom of a faulty internal joint is a knocking sound when the wheel hits a hole. Please note that before checking, it is advisable to perform chassis diagnostics to rule out other possible causes of knocking.
There is another method of checking - you can load the rear axle of the car to such an extent that the “nose” of the car rises higher, and the axis of the inner CV joint deflects. If a knock occurs under such conditions, this means that the internal CV joint has failed.
Other verification methods
As part of diagnosing constant velocity joints, you also need to know another way to determine which CV joint is crunching. However, this method is only suitable for cars with a manual transmission. The tool you will need for checking is a jack.
- First, the car is placed on a level surface;
- The wheels are set straight and hung out;
- By tightening the handbrake, the engine starts in neutral gear;
- Then, after squeezing the clutch, first speed is engaged;
- Then, in the cabin, the gas pedal is pressed and the brake pedal is carefully pressed (a load is created on the CV joint).
We also recommend reading the article about what signs indicate problems with anti-roll bar bushings. From this article you will learn what stabilizer bushings are intended for, as well as when and why they need to be changed, and how to replace stabilizer bushings with your own hands.
If the inner CV joint breaks, knocking noises will be heard when you press the brake. If the internal CV joints are working properly, the engine will stall and there will be no extraneous knocking noises. Next, turn the steering wheel all the way to the left or right and press the brake. If a crunching sound is added to the knocking sound, the external grenade is also faulty. Using this method, you can check the CV joints on the axle shafts on both sides.
Rumble (steering wheel turns, car stops)
Typically, this sound is produced by the hydraulic booster, which is installed on many cars. And there is nothing scary about this noise. When you get into the car, you may feel this sound - now you know that it will appear regularly. It is extremely rare that such a sound is detected when the steering wheel is turned in only one direction.
It seems that you have become accustomed to this sound, the car has been used for a long time, but the hum becomes louder and more distinct - now it can be heard not only when turning the steering wheel in the absence of movement, but also while driving. Here, be sure to try diagnosing the power steering. The most common cause of such noise is a lack of special power steering fluid, so the problem is often solved when such fluid is added to the power steering reservoir located under the hood (it is marked with MIN and MAX marks, they mean the maximum and minimum amount of fluid). Obviously, at the MIN level, fluid is most likely leaking from the system, so after topping up, you will need to check this level for some time (at least once a week).
The noise may also be caused by a breakdown of the power steering pump, weak tension of the power steering belt, as well as air flow that has penetrated into the power steering circuit. Alas, in all these cases you should definitely contact a car repair shop.
As a rule, problems with power steering are almost always accompanied by the need to apply more force than usual to turn the steering wheel.
Recommendations
As a rule, the main problem with CV joints is damage to the joint boots. For this reason, their condition must be constantly monitored at every maintenance. Even the slightest damage (cracks, tears, holes and other defects) is not allowed. If such defects are found, the CV joint boot must be replaced immediately. Please note that ignoring this rule leads to breakdown of this unit.
Moreover, if the CV joint crunches, this indicates critical wear. In practice, the problem can be “preserved” by updating the joint lubrication. However, this does not allow us to talk about the reliability and durability of the unit after such maintenance.
We also add that the maximum load on the CV joint is created if the driver accelerates heavily with the wheels turned out. If there is such an opportunity and you need to overcome an obstacle (for example, driving onto a curb or accelerating sharply when turning), it is better to put the wheels as straight as possible in order to reduce the load on the CV joint.
Shock absorbers (struts)
If you take a classic VAZ 2101 - 2107 car, then either the shock absorber itself (strut) or its mounting location may knock, provided that the bracket is released.
The lower silent block of the shock absorber may also knock.
If the strut is unscrewed at the top or the upper bushings are worn out, this can also lead to knocking noises on bumps.
Pay attention to the spring; if it is broken, knocking noises will be heard due to the coils playing with each other; this is also typical for other car models. As for shock absorbers VAZ 2108/09/10 and above, a slightly different picture emerges here
As for shock absorbers VAZ 2108/09/10 and higher, a slightly different picture emerges here.
If the supports and ball bearings are intact, and the sound comes from the strut area, then it is possible that the shock absorber nut is knocking, especially on bumps.
Those. A small gap may form between the nut, strut and shock absorber, which will lead to knocking.
To solve this problem you need to tighten the nut. To do this, jack up the car and insert a wooden stop between the disc and the side member to prevent the wheel from spinning.
Lift the corrugation and lubricate the threads of the rack with oil (can be worked off).
Take a number 3 gas wrench and use it to tighten the nut. Use a pipe for leverage.
Well, check the rack for leaks; if it is broken, it can also knock.
If two front struts are broken, then during sharp braking the car will nod off, and when accelerating, the front end will lift up.
Preventing knocking noises
All of the above problems can arise not only with domestic cars, but also with expensive foreign cars. And the difference between these cars comes down only to the time after which the malfunction appears.
Naturally, a foreign car will pass more without a malfunction than the same Priora. But repairing a foreign car, if, for example, its CV joint has failed, will cost much more.
In most cases, knocking noises are caused by inadequate road surfaces. Moving over bumps and holes leads to the fact that all fasteners begin to weaken, hence the appearance of backlash.
Knocking in a car engine, causes, diagnostic methods
To prevent knocking noises when turning the steering wheel, periodic inspection of all elements is required. Moreover, this will require very little, and you can do everything yourself.
The car is placed on an inspection hole or overpass, after which, while under it, you should carefully inspect all the elements, check the tightness of all fasteners with wrenches, tighten the nuts and bolts if necessary, swing the levers with a pry bar, checking for play.
If you do all this periodically, you can avoid the occurrence of knocking noises, or at least increase the life of the car before they occur.
Also, when traveling, you need to adhere to the speed limit, and go through difficult sections at low speed in order to slightly reduce the load on the elements of the suspension steering mechanism.
And if in front of you unexpectedly there are depressions in the road surface, then slow down the car (the car will seem to nose down), and immediately before the problem section of the road, release the brake pedal.
The front of the car will rise, thereby unloading the front suspension, and the car will coast over uneven roads without much damage to the chassis.
