Engine mount malfunction: causes, symptoms, replacement

03.07.2019

(Votes: 5, Rating: 4.2)

Issues discussed in the material:

What is an engine mount or mount?
For what reason can an engine mount break?
How to understand that the engine mount has become unusable
How to change an engine mount

An engine mount is a support structure that maximally softens vibrations of the engine in the engine compartment of the car. An ideally functioning cushion should completely dampen any engine vibrations, preventing vibration from spreading throughout the body.

What are engine mounts

A car engine weighs quite a lot, and due to the vibrations it creates during operation, the engine must be securely fastened. When rigidly attached to load-bearing body elements, the fasteners will be subject to significant variable loads while driving over uneven surfaces. In this case, they will fail very quickly.

The vibration will also be transmitted to the entire body. On the one hand, this will create discomfort for the driver and passengers, on the other hand, it will negatively affect the durability of all components of the car.

Special supports called pillows are designed to cope with this problem. They dampen the vibrations created by the engine and at the same time reliably fix it from displacement.

The motor can rest on 3-5 supports, depending on the specific car model. Mounts located front and rear control idle vibration when the engine reaches peak loads.

On Soviet cars, these cushions were ordinary rubber inserts of sufficient strength with fastening points. Modern products can have different appearances. Among them, rubber-metal and hydraulic supports stand out. On front-wheel drive cars, engines and gearboxes rest on 4-5 supports, two of which are located under the gearbox.

The rubber-metal product, in turn, can also be made in different ways. Often this is a steel or aluminum cylinder with a rubber silent block inside. Sometimes cars are equipped with a “lamp” made of aluminum alloys with a rubber insert.

As standard, the supports are arranged as follows:

The right airbag is located on top and attached to the body side member.
The front support is usually located on the engine beam and is visible from below.
The rear support is fixed to the underbody or front body subframe. Some engine modifications do not have this support.
Under the gearbox, closer to the rear of the engine, there is a common cushion.

The modern design of an electrical hydraulic cushion looks like this:

Pillows of this type are able to adapt to any engine operating mode, maximally damping the resulting vibrations and making driving the car more comfortable.

The greatest loads on the supports occur at the moments of starting, moving and stopping the vehicle. A malfunction of the support leads to an increase in the load on the motor and transmission units and, as a result, to an increased risk of their breakdown.

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Causes of engine mount malfunction

The failure of airbags is not caused by any specific reasons. And yet, experts pay attention to certain indirect factors that ultimately lead to the malfunction of these elements.

Insufficient suspension performance
To improve handling and improve the appearance of their foreign cars, owners often install low-profile wheels and high-stiffness shock absorbers. Indeed, a positive effect is achieved, but only until the moment when the car drives a wheel into a hole. As a result, vibrations are not completely damped and are transmitted to other suspension components: ball joints, levers, and including engine mounts. The car body also experiences stress. Therefore, when changing the suspension parameters, you need to be extremely careful on uneven surfaces.
V-shaped engine
A motor with such a cylinder arrangement, as a rule, begins to vibrate earlier at idle compared to an in-line engine. Four-cylinder in-line units have the lowest risk of malfunction because they have optimal balance and better weight distribution. The operation of the crank mechanism of such an engine creates a minimum of vibrations and almost does not load the support.
Driving style
The driver's driving directly affects the condition of many automotive components, including engine mounts. For example, the supports experience significant loads during sudden acceleration and braking. The loads are explained by the ordinary laws of physics due to a shift in the center of gravity. Accordingly, the service life of the airbags decreases in direct proportion to acceleration during braking and acceleration.
Condition of the roadway
Even the most careful driving style cannot eliminate the occurrence of faults in the airbags if the road surface leaves much to be desired. And in this case, the entire suspension suffers. If possible, it is better to avoid sections of bad road - this is the only way to protect the engine mounts and suspension as much as possible.
Natural wear
Rubber-metal support is a fairly wear-resistant element, and the first signs of its malfunction may appear only after reaching 200 thousand km under normal operation. For particularly careful car owners, engine mounts last for decades without replacement. However, in addition to mechanical wear, supports are subject to negative thermal effects. As a result of repeated temperature changes, the rubber cushion loses its elasticity over time. It is this malfunction that occurs most often, which is why the product usually fails and must be replaced. In this case, cracking and delamination of the material occurs, and the support ceases to effectively dampen vibrations and extraneous noise.

There is also another, less illuminated, but nevertheless influencing the durability of the product factor. It turns out that regular engine washing can extend the life of the pillow. It's all about the oil layer, which gradually covers during operation all the external surfaces of the engine components, including its supports.

The negative impact of oil on rubber is obvious. Oil that gets on the rubber surface of the supports reduces the elasticity of the cushions and, accordingly, reduces their service life.

Antifreeze, gasoline fuel and brake fluid affect rubber in a similar way. It is recommended to avoid contact of these liquids with the surface of the supports. And regular engine washing will not only extend the life of the airbags, but will also help to promptly identify their malfunction, as well as problems in other attached parts.

Wear of the bearings manifests itself in the form of a distinct engine vibration felt from the passenger compartment. In addition, when you press the accelerator pedal, you can feel a single blow, repeated after releasing the pedal.

You will see a faulty engine mount when you open the hood. If, when you press the gas pedal all the way, the engine seems to rise a little, this may indicate wear on the support under the gearbox. Critical wear of one of the remaining pillows warps the engine in the corresponding direction.

At the initial stage, such a malfunction as natural wear and tear of engine mounts does not pose a serious danger. In the future, any vibration gradually destroys every mechanism on which it acts. Also, an advanced case of wear on the cushions can lead to the engine breaking off its mounts, and this is already a dangerous consequence.

If you stop monitoring the integrity of the engine mounts, at one point these cushions will come off, and the engine itself will break off its mounts. But for this to happen, you need to endure a noticeable knock from the engine for a long time while driving and not pay any attention to this knock.

Moreover, even after only one support is torn off, there is no guarantee that the car will move on without problems. There are known cases of support separation, in which the engine tilted and the lower pulley clung to the beam, resulting in damage to the timing belt.

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Features of the procedure for replacing motor mounts

It is necessary to ensure easy access to the cushions, so in addition to wrenches, you will also need a good jack. Let's look at the list of measures to replace a defective cushion using the example of a rubber-metal product:

Loosen the nut securing the airbag to the body.
Jack up the engine and remove the bolt.
Unscrew and remove the faulty support.
We install a new one and tighten it.
Jack up the engine and insert the mounting bolt.
Tighten the bolt and lower the motor.

Note! If the vibration, on the contrary, increased after installing new cushions when the car was warmed up and running, then the supports need to be centered. To do this, you need to loosen all the bolts securing the pillows and tighten them evenly until the vibration disappears.

Self-replacement

If a visual inspection reveals problems in the pillow, it should be replaced as quickly as possible. Start by purchasing a new part. It should be noted that it is better not to buy this spare part for disassembly, even if it is in good condition. In this case, saving money may cause more harm than good. Ideally, it would be to buy an original part.

Remove the terminals from the battery. Raise the car to a height that will allow access to the engine from below. In this case, you can use a jack and wooden blocks as support.
Raise the engine with a jack to release the load on the required part.
Remove the bolts that secure the cushion to the engine and body.
Place the new part in place, guiding it properly into place. Tighten the mounting bolts well. It's best to tighten them while the engine is running to avoid excessive vibration in the future.
Once you have finished installing the cushion, put all the dismantled parts back in place.

In each individual case, it may be that there is no convenient access to replace the part. In this case, try to remove those components that prevent you from making a replacement.

Sometimes this operation may require another person to help guide the motor while you push the part into place. If we are talking about the top cushion, then, as a rule, it will not be difficult to inspect it and, if necessary, replace it. It will be possible to do without a hole.

Periodically check the condition of the engine mounts on your car. As you can see, this is not at all difficult, but it can help avoid many problems in the future and provide you with a comfortable ride in any conditions. Remember that a car feels when it is being looked at and then thanks its owner for a long and good service.

What are the types of engine mount malfunctions?

The reasons for failure of engine mounts can be different. The most common of all support malfunctions is the separation of their rubber part. Despite the declared long service life of the product, the increased load on the support tears its rubber part. For fans of high-speed driving who accelerate sharply at the start, the airbags under the engine quickly fail.

Under certain conditions, rubber tends to dry out and lose elasticity. Sometimes hitting an obstacle causes the aluminum bracket to come off. Drops of oil falling from the engine or gearbox onto the rubber surface inevitably corrode it, and the service life of the support is sharply reduced. In short, a malfunction of the engine mounts, the symptoms of which are listed below, at a minimum causes discomfort when driving, and in some cases can lead to dangerous situations.

The main signs of broken supports are:

The engine runs quite smoothly, but strong vibration is felt throughout the body.
Pulling away and braking is accompanied by dull knocks and clicks under the hood.
When driving over uneven surfaces, impacts occur in the front of the car, which are transmitted to the gearshift lever. Changing gears in a car with a manual transmission during impacts becomes difficult.

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"Mazda Demio"

Signs of a malfunction of the left engine mount of the Mazda Demio are knocking and vibrations. The supports bear a heavy load. It is worth carefully monitoring the condition of the airbags; a faulty part can damage the engine. This car has three airbags: left, right and bottom. The second is located near the engine oil filler neck. The left support is located under the battery. The lower one is located directly opposite the junction of the engine and automatic transmission. The methods for diagnosing a malfunction in this case are the same as for any other cars - this is a visual inspection and checking for play.

How to identify a faulty engine mount

An initial check of the supports can be carried out independently, without contacting service center specialists. It is usually not difficult for even a driver who is not very experienced in repairs to identify a malfunction.

The simplest diagnostic method is to manually rock the engine under the hood, pay attention to the knocking noises that arise and use their source to find the damaged cushion.

Another method requires an assistant. The driver sits behind the wheel of a car with the hood open and fixed, starts the engine, shifts the lever to first gear and begins to move forward in small jerks. Then it moves backwards in a similar manner when reverse gear is engaged. At this time, the assistant visually evaluates engine vibrations.

For a more precise diagnosis, you must first accurately determine the location of the engine mounts. If possible, the supports are first inspected for any noticeable damage or defects. For the most complete inspection, it is recommended to have an inspection pit, overpass or suitable lift.

If nothing is found during a visual inspection, you need to move on to the next stage, where you will need the help of a partner. Armed with a pry bar, one person moves one of the pillows under study. At this time, another person carefully observes the appearance of cracks or tears on the rubber element when the support moves. Sometimes it is when rocking or moving that damage to the pillow appears that is not visible when it is stationary.

A pillow with a detected malfunction must be completely replaced. Replacing just one rubber part pressed out of the cylinder in order to save on spare parts most often does not give the required result.

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Why is it needed?

The engine of any car is attached to the body through special elastic cushions. They are needed to smooth out vibrations, taking them upon themselves. Thanks to them, vibration is practically not transmitted to the body and is not noticeable inside the cabin. The car's engine simultaneously receives protection from adverse consequences, such as impacts when the wheels fall into a hole or pothole in the roadway.

A hydraulic cushion is a device that can provide the most suitable conditions for stable engine operation. Because it itself adapts to the intensity of vibration.

At low vibrations the cushion is soft, but as it increases it becomes harder to better dampen the vibrations of the machine.

Replacing the engine mount if a malfunction is detected

If you need to replace the engine mounts, the signs of malfunction described above will usually allow you to get to the nearest car service center or your own garage on your own. But you should drive carefully, if possible at a speed no higher than 60 km/h. The rear or left cushion is usually subject to wear. A detected malfunction of one support will most likely entail the replacement of the second pillow. At the end of the inspection, you need to purchase the necessary spare parts in advance - you won’t be able to go get them by car while replacing the airbags.

Preparing to replace the engine mount It is recommended to carry out work on replacing supports in a warm place, since the rubber used at low temperatures hardens and loses elasticity. This will significantly complicate the process.
It is also advisable to drive the car into an inspection hole and carry out the replacement from there, having first disconnected the battery terminals. They often begin to inspect the left front side of the engine, where the airbag malfunction appears in most cases and access to which is most convenient.
A torn mount can be repaired, since the price of a new mount for a foreign car engine is about 2,000 rubles (and for an SUV it is twice as high). If the rubber element is damaged, the support will have to be changed in any case.
Engine mount replacement process
First of all, protective elements are removed from the motor to facilitate access to the necessary parts. A jack is then placed under the engine to provide support while the mounts are removed. If the process takes place in a viewing hole, you can lay a wide, fairly strong board across it and install a jack on it.
Next, the unit is raised with a jack until it is possible to freely unscrew the support being replaced. After unscrewing the mounting screws and removing the old support, a new one is installed in its place, and the operation is repeated in the reverse order.
Replacing a rear airbag is usually associated with certain difficulties. This support experiences the greatest loads during engine operation. As a result, all fasteners are deformed, including bolts. The shape of the fastener differs from other supports.
Here a jack will no longer be enough. To free the support, it is best to hang the motor from the upper beam. If this is not possible, you can build a crossbar on two glasses, lifting the engine with a jack in advance. In some car models, external components may interfere with troubleshooting and will have to be removed. It is more efficient to cut off a severely deformed pillow fastening bolt with a cutting wheel. Sometimes they try to align and unscrew such a bolt, but after a while it will still have to be replaced.
The old support often sticks to the frame and forms rust due to the accumulation of dirt. Oil or a product like WD-40 can help remove it. It is important to install the new rear support correctly. The arrow on the support should point forward, in the direction of travel of the machine. The rest of the assembly is carried out in reverse order.
After replacing the rear support, you can proceed to the right one. Here, too, there is a possibility of encountering deformed bolts, but a more serious problem lies in the generator or car air conditioning compressor located here. It is known that removing the compressor can lead to depressurization of the circuit and leakage of refrigerant.
If the repair takes place at a service station, it is better to subsequently check the air conditioner for possible malfunctions. Short-sighted car service employees sometimes remove the compressor themselves to save time, without warning the car owner about it.
In foreign cars, in most cases, the right engine mount is located closer to the front. Therefore, to access this cushion, the right headlight and radiator grille are often removed.
Some of the deformed bolts cannot be cut off even with a grinder, since access to them is limited by other neighboring elements or simply cannot be reached. In this case, it is better to use a regular hacksaw, cutting off the damaged bolt by hand.
This procedure will take much longer, but at least this way you will not damage adjacent parts and components. The new support is placed in place of the old one as usual, in reverse order. When installing the radiator grille, you need to be careful - the radiator honeycombs are sharp enough to cut yourself.
Safety during operation
The most important thing is to fix the motor securely and safely. A second assistant is desirable for assistance and backup.

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"Ford"

Vibrations on the car body at idle and while driving indicate that the engine mounts are out of order or damaged. Signs of malfunction (Ford Focus 2 as well) may be different. Ford Focus cars use two supports. The right one is hydraulic, the left one is the gearbox support. In case of damage, it is recommended to replace both elements.

Naturally, you can replace only the damaged one and the vibrations will go away, but the new support will be subjected to significantly greater loads and will fail much earlier than its intended life. As a replacement, it is worth purchasing original parts. Inexpensive analogues last less than 20 thousand kilometers.

Useful tips

Motorists recommend replacing the support in warm weather. In winter, the pillow becomes very dull, and can only be removed after preheating (using a hairdryer or blowtorch). If the support does not come out, it is recommended to use VD-40 type lubricant or its equivalent from. Regular lubricant will not work for this.

Often dust and moisture enter the cavity of the old cushion, resulting in corrosion processes occurring on the cylinder. It is not possible to remove the pillow. If you are replacing the rear support, pay attention to the direction indicated by the arrow on the part. It must be installed in the direction of travel of the vehicle. Otherwise, there is a risk that the element will not withstand the load and will break.

Diagnostic methods

Signs of wear on engine mounts

Engine vibration at idle.
Extraneous knocks while driving, felt in the engine compartment or under the gearbox.
Jerks during dynamic acceleration of the car.
Knocks in the engine compartment when starting or stopping the engine.
Difficulty shifting gears.

On cars with hydraulic supports, in addition, acceleration dynamics may deteriorate. Visually, faulty airbags can be identified by delamination and ruptures of rubber dampers or breakage of aluminum brackets. An experienced specialist can also visually identify a sagging pillow by how severely its damper is deformed.

Types of pillows

Despite the variety of design options, the general purpose of the cushions is to act as an engine mount, i.e. dampen vibrations and vibrations of the power unit. The role of an engine damper is usually played by rubber (sometimes in interaction with the hydraulic properties of the oil), absorbing shocks and vibration, while preventing displacement of the power unit.

As an example, we can take the motor mount on the Niva. It is a rubber cylinder with plates with threaded rods welded to it. The left and right engine mounts are absolutely identical, the third, which supports the gearbox, has a slightly different appearance and is mounted on a crossbar mounted on the bottom of the car.

The dimensions of the supports and their attachment points are designed in such a way as to prevent displacement of the power unit, while the weight of the engine compresses the cushion, and is distributed in such a way that rupture of the rubber due to its shear deformation is practically eliminated. In a similar way, the engine, also located longitudinally to the axis of the car, was installed on " Volgakh".

But with a transverse engine arrangement, it is somewhat more difficult to balance it, due to the design of the power unit as a whole. Therefore, the supports most often take the form of suspension arms, which have silent blocks as an engine damper, as on the additional supports of the VAZ 2112: This design of supports is also sometimes caused by the need to support the points of the engines most distant from the body, which after modernization have acquired a large mass.

The use of additional supports allows you to install heavier engines without significant changes to the design of the car. The most typical method for relatively small power units is the method of “hanging” them, as on 2108 -09. The engine assembly with gearbox has three mounting points:

left engine mount;
rear (lower) engine mount.

How do engine mounts work?

The cushions work similarly to the silent blocks of the suspension arms, that is, they twist the rubber. Therefore, on cars driven primarily on bad roads, because... such supports turn out to be unreliable - the rubber delaminates. More compact cars, which are relatively heavy (in relation to the total weight of the car), are suspended somewhat differently - the rubber damper in them works in compression-tension, which increases its service life.

Hydraulic (or hydromechanical) engine mounts differ from conventional ones in that they have variable stiffness. This is achieved by taking vacuum from the engine. When a certain number of revolutions is reached, the valve separating the support chambers closes.

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As a result, the liquid (antifreeze), which previously flowed from chamber to chamber, begins to play the role of an elastic element. Externally, such supports differ mainly in the presence of a fitting for connecting a vacuum hose and cable. Such cushions are intended to dampen vibrations from the motor, the bulk of which “lies” on other supports.

So, the owner believes that the engine mount has failed. The symptoms of the malfunction were confirmed. Next, you need to check the condition of the supports. In order to ensure the integrity of these parts, you will need a jack and any supports - wood stumps, pallets, tires.

Anything will do. It is also advisable to prepare a crowbar or a thick stick. Let's look at how to determine if an engine mount is faulty. To do this, it is recommended to place the car on the most flat surface possible. Then the car needs to be lifted using a jack, then a prepared support should be installed under the engine. It could be a log or something else. It's better to remove the jack.