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Crankshaft oil seal: replacement and selection

When and why it is necessary to replace crankshaft oil seal

On the average, operational lifetime of the front and rear crankshaft oil seals is 100,000 – 150,000 kilometers of mileage. Premature replacement of these parts can be required due to elasticity loss, mechanical defects or deformation, thermal damages, free play in the place of contact between the oil seal and the crankshaft. Also the component is replaced in case of its displacement.

Loss of car part elasticity is often the result of its drying-out due to long-time (more than half a year) non-use of the car. Moreover, the oil seal can freeze if the car was left in freezing temperature. As a rule, defects and deformation of the component are the result of crankshaft vibrations. Also the oil seal can be damaged because of improper installation. Melting of the part is caused by engine overheating, its displacement from the mounting seat – by increased crankcase gases pressure.

The main sign of crankshaft oil seal defect is leakage of oil. During this, oil level is reducing, which is noticeable at checking with the help of the dipstick. If the rear oil seal got damaged, clutch slipping can take place. During scheduled replacement of the timing belt you can find oil stains on it, which also point out defectiveness of the crankshaft oil seals.

It is recommended to perform replacement of the oil seal at a service station: the procedure presupposes usage of a lifting device. Moreover, replacement of the rear oil seal involves removal of the gearbox and the clutch assembly; and for demounting of the front one, a special remover tool is necessary.

How to select crankshaft oil seal

These components are made of various materials: fluororubber (FPM, FKM), polyacrylic rubber (ACM), Teflon (PTFE), butadiene-nitrile rubber (NBR), silicon rubber (MVG, VMQ). The most widespread oil seals are made of fluororubber. This material is resistant to high temperature and influence of motor oil.

Also the crankshaft seals are divided into double-edge (with the dust boot) and single-edge (without the dust boot) ones. The advantage of the parts with the dust boot lies in the fact that they not only prevent oil leakage, but also protect the unit from ingress of dust and moisture.

The crankshaft oil seals can be of various types according to the cross-section type. So, there are parts with metal coating, with smooth surface, with grooved surface, with hydrodynamic effect. The grooved components improve the mounting tightness, while the hydrodynamic ones are considered more durable.

In order to make the crankshaft oil seals serve faultlessly during the whole operation lifetime, give preference to products of reliable manufacturers. High-quality components are presented in the assortment of Ajusa, Corteco, Elring, Glaser, Payen, Victor Reinz and other brands.

During purchasing these car parts you need to consider their mounting location: in the front or in the rear. No less important selection parameter is the type of oil seal, its height, outer and inner diameters. Moreover, you need to take into account the direction of oil grooves rotation.