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Crankshaft: replacement and selection

When and why it is necessary to replace crankshaft

Manufacturers do not specify crankshaft service life. Replacement is performed in case of detail deformation and at cracks appearance on it. Also, the component is replaced in case of main and crankpin journals wearing, insert bearings melting, side surface wearing under thrust washers. Damage of keyways and mounting seats under pins, sleeves and seals, wear of the thread in fixation holes are also the causes for crankshaft replacement.

Appearance of cracks on the car part is often explained by a low oil level or insufficient pressure in the lubrication system. Usage of low-quality oil also influences negatively crankshaft condition. Moreover, component damage can be caused by breakdown of the piston and connecting rod as a result of hydraulic shock in the cylinder.

Wear of the thread, keyways and mounting seats for pins and sleeves is, as a rule, the result of incorrect mounting of fixation bolts. Moreover, appearance of metal dust in motor oil negatively affects crankshaft condition.

The characteristic sign of component main and crankpin journals wear, as well as that of their sleeves, is thumping sound from the crankshaft which increases at acceleration. Clanking sound at start of the cold engine and blue exhaust gases can point at wear-out of the cylinder-piston component group.

Also, component defects can be detected by increased motor oil consumption (you can learn about it checking the working fluid level with the help of the oil dipstick) and noticeable lowering of engine power. Cracks and deformation of the crankshaft can be found at its demounting, for example, during maintenance or engine repair.

Replacement of the spare part should be entrusted to service station specialists because this procedure presupposes demounting of the engine and some other components which trouble access to the crankshaft. During replacement of the crankshaft you should inspect and replace, if necessary, caps of crankshaft main bearings and their fasteners, connecting rod bearings and thrust washers.

How to select crankshaft

According to manufacturing technology there are cast and forged crankshafts. The components also differ from one another by production material. The cast car parts are produced of high-resistance steel, the forged – of cast iron.

The crankshafts are divided into types according to throws quantity. It coincides with engine cylinders quantity. Moreover, there are crankshafts with one counterweight, with two counterweights and without any. The car parts with one counterweight are usually installed on low-powered engines, on more powerful ones – with two counterweights.

Components longevity mostly depends on their manufacturers. Qualitative crankshafts are presented in the assortment of DT, Japanparts, Bugiad, Febi Bilstein and other brands.

The car part should be bought according to the brand, model, car production year, type and power of the engine. Important parameters during component selection are quantity of engine cylinders, diameters of main bearings and crankpin journals.