The main signs of wear and diagnostics of pillows (supports) of the engine
In addition, unlike a static sleeping person, a moving car experiences multi-vector loads (especially on rough roads) that affect its components and mechanisms. The engine assembly with the gearbox is a very heavy unit, its vibrations will quickly lead to the destruction of the fasteners if it is rigid and not elastic. To prevent this, the pillow (it is also a support) of the engine is called upon - an elastic element that fixes the power unit, does not allow it to move and dampens vibrations associated with the operation of the engine.
STRUCTURE AND CLASSIFICATION OF ENGINE SUPPORTS
Engine support. Vehicle engine mounting system on supports. — Dictionary of auto mechanic
In modern cars, depending on the design, from 3 to 5 pillows (supports) of the engine, or rather, the power unit, are used, because the elastic mounting system is combined, without fail, with the gearbox. Most often, pillows are located in the engine compartment as follows:
front support - on the motor beam;
the upper support is attached to the body side member (sometimes to the shock absorber cup). More often located on the right;
the rear support, if any, is fixed to the bottom or to the front subframe;
under the gearbox, closer to the rear of the engine, a common cushion is fixed.
According to the type of structure, the engine mounts are divided into two main groups:
Rubber-metal. In shape, they are in many ways reminiscent of other suspension elements (for example, silent blocks of levers). This is either a metal cylinder (steel or aluminum) with
rubber insert, or a bracket with a rubber spacer, or an elastic element placed between two metal washers or plates. Additionally, it can be equipped with buffers (impact bumpers) to soften shocks and / or a spring to increase the rigidity of the support. For the same purpose, and also to increase wear resistance, polyurethane can be used instead of rubber. Rubber-metal supports can be both collapsible and non-collapsible.
Hydraulic. This type of engine mounts is the most modern and progressive. The principle of operation of a hydromount is similar to a classic shock absorber: vibrations are damped by moving fluid between the chambers. They are separated from each other by a rubber membrane in which the throttle is located. The difference is that inside the hydraulic support, as a working fluid, there is not oil, but propylene glycol (used, among other things, in the production of antifreeze).
The main advantage of hydraulic bearings is that the fluid is more dynamic and responds faster to vibrations. Hydraulic cushions are often installed as leading ones (usually in pairs) together with classic rubber-metal cushions, structurally redistributing loads. This leads not only to damping optimization, but also contributes to an increase in the life of conventional pillows.
Hydraulic supports are divided according to the type of control:
mechanical, controlled according to the principle described above (at small amplitudes of oscillations, the membrane works, at large amplitudes, a channel-overflow (throttle) is connected);
electrovacuum, where, in addition to the hydraulic one, there is also an air chamber, to which either atmospheric air or vacuum from the intake manifold is supplied using an electromagnetic valve. Such supports are controlled by an electronic engine control unit (ECU) based on the readings of the crankshaft position sensor (DPKV);
electromagnetic, where the hydraulic chamber is divided by a movable diaphragm, to which an electromagnetic coil is attached, enclosed in a magnet along the edges. When voltage is applied and turned off, the coil moves with the diaphragm. Just as in the previous case, control is carried out by means of the ECU, but according to not only the readings of the DPKV, but also the accelerometer, which fixes engine vibrations transmitted to the body;
magnetorheological (dynamic), whose principle of operation is approximately similar to the shock absorbers of some adaptive suspensions: the property of a magnetorheological (i.e. ferromagnetic - saturated with nanoparticles of materials containing iron) liquid is used to change density under the influence of magnetic fields. They are also controlled by the ECU, but already based on the input signals of a whole range of electronic sensors.
However, despite such a high-tech design, the hydraulic component of the support does not perform the main, but an auxiliary function in damping vibrations. As in the case of rubber-metal bearings, rubber holds the mass of the engine. In the event of a fluid leak, the performance of the hydraulic support is not completely lost, and even not always immediately noticeable. Nevertheless, continued operation of a car with faulty engine mounts is highly undesirable: vibration amplitudes increase, which can lead to damage to the engine, attachments, pipes, hoses, etc., and to accelerated wear of other still serviceable supports.
REASONS FOR FAILURE OF ENGINE PILLOWS (SUPPORTS)
How to diagnose engine mounts? - Online magazine for motorists
Pillows of most modern cars
it is a very reliable and durable part, the resource of which is often 150-200 thousand km, but only if it is properly used in relatively benign conditions. Factors that accelerate wear include:
constant driving on rough roads and rough terrain;
frequent engine starts at extremely low temperatures;
body rolls and distortions (associated with overload or malfunction of suspension elements);
engine overheating;
contact with the rubber part of the support of technological liquids (gasoline, diesel fuel, oil, antifreeze), engine contamination;
sharp jerks from a place, sharp braking, turns;
mechanical damage (running into obstacles, broken brackets);
interference with the factory suspension parameters: changing (tuning) the stiffness of shock absorbers, springs, using discs and tires of non-standard diameter.
Let us explain: that the rigidity of the engine mounts is specially calculated according to the characteristics of a particular car model, and any change in them can adversely affect the durability of the parts. The rubber used to make the rubber-metal cushions or the shell of the hydraulic bearings is not resistant to oil and fuel, and the ingress of both the liquids themselves and the dirt saturated with them on it leads to the destruction of the bearings, just like a violation of the temperature regime.
SIGNS OF A FAULTY ENGINE PAD
The fact that one or more pillows have completely or partially lost their working capacity can be guessed from the changed behavior of the car. Although the situation may differ depending on the type of part, as well as the make / model of the car, it is recommended to pay attention to the following symptoms:
vibration transmitted to the body and most of all felt at idle - especially if the engine is running smoothly;
knocks, clicks, small bumps under the hood when starting or braking;
extraneous sounds when driving through bumps, transmitted to the manual transmission lever;
steering wheel vibration at high engine speeds;
difficult inclusion of manual transmission gears, and in some cases their knocking out.
In addition, it is possible to change the geometry of the engine location relative to other elements of the engine compartment, reduce the gaps between equipment, contact pipes, wire harnesses and other elements that were previously at a distance from each other.
In some cases, problems may not be caused by the condition of the engine mounts, but by their loose fastening. In any case, when the above symptoms appear, it is necessary to diagnose the car.
DIAGNOSIS OF ENGINE MOUNTS
How to check the engine mounts yourself? simple tips - Repair the Car!
The initial check of the integrity of the engine mounts can be carried out independently.
The first stage is a visual inspection of the supports in the field of view. Cracks, tears, delamination of rubber layers, its delamination from metal parts will indicate wear. At hydraulic supports, in addition, smudges of the working fluid testify to the failure.
Next, you can try to move the engine in the area of \u200b\u200bone of the supports using a crowbar (mount). Increased play will indicate a decrease in the elasticity of the pillow or loose fasteners. It is better to work with an assistant so that one person has the opportunity to carry out a visual inspection without distraction.
Having seated the assistant behind the wheel, ask him to start the engine and move slightly (a few centimeters) - first forward, then back. An increased amplitude of engine oscillations, “pecking”, vibration, knocks will also indicate a malfunction of the pillows. It should be borne in mind that, unlike conventional rubber-metal engine pillows, it is almost impossible to check the performance of hydraulic bearings - a faulty support will almost as elastically respond to the applied force as and working, without experience or comparison with the same obviously serviceable car, it is unlikely that it will be possible to determine the difference. Indirectly, malfunctions of the hydraulic bearings can be obtained through Check engine errors, which will be issued by the control unit when increased engine vibrations are detected.
There are some other verification methods that are specific to certain types of cars. For example, on diesel models equipped with electric vacuum supports, you can alternately disconnect the vacuum hoses from the pillows on the engine idling and plug them with your finger. A change in the sound coming from under the valve cover will indicate a malfunction of this particular support.
There are a lot of diagnostic nuances, therefore, in order to correctly check, and even more so, replace the engine mounts, seek help from professionals. Best of all - at the service station of the Wilgood smart car service network. And then the work of your engine will always be smooth - like a dream of a healthy person.