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Common Causes of Oil Seal Failure

Modify: Sep. 29, 2022

The oil seal, also known as the crankshaft retainer, is a small device, but one that is vital to ensure the proper operation of the engine. It plays a key role in all the moving parts of the engine, acting as a physical barrier. This mechanical seal has the dual purpose of sealing the rotating shaft to maintain the necessary lubrication (to avoid leakage) and to prevent other foreign bodies from contaminating the shaft and bearings in the rotating shaft unit.


It is usually used at the joint of two lubricated parts so that they are sealed on both sides. It thus ensures proper engine operation and helps to keep the vehicle's distribution system in better condition.


Oil seal characteristics

Several variables must be considered when choosing an oil seal. Physical dimensions and materials will vary depending on the environment in which they are used. In addition, oil seals must remain lightweight, compact and have high self-lubricating properties.

Oil Seal

Oil Seal

Most oil seals consist of a number of basic elements that make up their structure, such as sealing elements, metal housings and springs.


Dust lip: prevents particles from reaching the sealing lip.

Sealing lip: ensures dynamic and static sealing.

Metal case: the metal case supports the rotary shaft seal and ensures structural stability.

Springs: spiral shape, ensuring constant pressure and maintaining optimum force on the shaft.

Aspects to consider when selecting an oil seal


Operating conditions such as engine temperature, position, size, pressure and shaft speed determine to a large extent which oil seal assembly is best suited to each individual application.


Some aspects to consider when selecting this assembly are

Temperature: The temperature within the oil seal environment is a major factor in determining the oil seal composition. There is usually a set temperature range that is optimal for this material. If the operating environment is too cold, the seal may become brittle and at high temperatures the seal material may exhibit increased elasticity and become leaky.

Auto Oil Seal

Auto Oil Seal

Pressure: As pressure increases, the radial load and the friction of the seal lip in contact with the shaft increases. As with temperature, there is a recommended pressure for each oil seal to achieve optimum performance. Excessive pressure will cause the seal to wear faster, thus reducing service life.


Shaft speed: The speed at which an oil seal can operate effectively depends on the conditions outlined earlier and the design of the seal itself. Some designs allow a range of maximum circumferential speeds and are therefore more suitable for larger shaft diameters. Speeds below and above the recommended range can cause friction, which can affect the seal material.


Common causes of oil seal failure

Like any component of an engine, oil seals can wear out. Over time, they can cause lubricating fluid to leak.


The most common causes of oil seal failure include


Inaccurate installation, such as placing the seal in the wrong position in its housing or improper handling.

Improper use of sealant.

Defects on the shaft (burrs, corrosion, etc.) that will directly affect the life of the oil seal.

Premature deterioration of the oil seal material due to extreme temperatures causing cracking or expansion of the component.

Other maintenance factors, such as insufficient lubrication within the engine.

Oil leaks: the most common failure of oil seals


Finding oil spots under a parked vehicle can be a worrying and stressful experience for any owner. If the seal is leaking a small amount, oil may start to accumulate at the bottom of the engine. However, as the leaks become larger, oil leaks will become visible on the front side of the engine.


Wear and oil loss are still the two most common signs of engine seal failure and, if left unattended, can lead to vehicle system failure. Regular maintenance and routine oil changes will minimise oil seal related problems and potential oil loss.


Wherever you need to prevent leakage, exclude contaminants, contain pressure, or reduce friction, the mission of the oil seal manufacturers is to help you to find the right sealing solution for your particular application requirements and commercial needs. Therefore, KDIK offers an extensive range of seals for general automobile, truck, bus, motor coach, trailer, automobile parts. Just contact us!

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