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Engine and transmission mounts: replacement and selection

When and why it is necessary to replace engine and transmission mounts

The components are rather durable details and correctly work for more than 100 000 operational kilometers. It is recommended to perform their replacement as the malfunctions occur.

As a rule, necessity to install new engine or transmission mounts appears in case if old ones got depressurized, became stiff, cracked or delaminated, the aluminium carrier bracket or mounting holes got damaged. Often these defects are connected with driving in off-road conditions, aggressive driving style, especially sharp starts and brakings, hitting obstacles, oil, antifreeze or braking fluid getting onto the parts surface, temperature drops, low quality of engine assembling.

Engine mount defects are easily noticeable by vibrations which are felt in the cabin at car acceleration, by unusual sounds and pushes at engine start or gear shifting. Wear of the mounts is also characterized by knocking and extraneous noise which often appears at unevenness over-running.

In order to avoid other defects, the engine and transmission mounts are better to replace by kit.

How to choose engine and transmission mounts

Depending on construction there are rubber-metal and hydraulic mounts. The rubber-metal ones are a rubber damper which is put between two metal plates. They are the most common. They can have demountable and non-demountable housing. Their main advantages are construction simplicity, reliability and low price. On some cars such as sports cars more stiff components are installed. Their construction includes polyurethane instead of rubber.

The hydraulic mounts are more modern. They consist of two chambers filled with special fluid and divided by the membrane, function of which is to absorb vibrations at idle. At accelerating when the engine works at increased rpm, damping is performed due to flowing of working fluid from one chamber to another. Stiffness of such mounts, as well as stiffness of the rubber-metal ones, is specified at manufacturing and is adjusted for the specific car model and is constant.

The hydraulic mounts can be equipped with the electronic control system. They absorb vibrations better at all the engine operation modes but are generally used on the expensive cars due to their high price. Such mounts are called active. Their stiffness changes smoothly according to the loads applied. Stiffness can be adjusted in several ways.

In order to have the engine mount function properly, you should prefer production of well-known manufacturers. The best of them are Febi Bilstein, Metzger, Mapco, Lemförder and others.

Moreover, when choosing a part, you should take into account the mounting side and location of components. Parts of different types may be installed at the top and bottom fastening points of engine and transmission. Choosing the damper for the two-piece mounts, pay attention to its length, outer and inner diameter, because correctness of component installation depends on these characteristics.