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Piston rings: replacement and selection

When and why it is necessary to replace piston rings

Averagely, service life of these components is no less than 150 000 operational kilometers. But service life of the piston rings can be significantly reduced at violation of car operation conditions. New rings are installed prematurely in case of deformation of old ones as a result of elasticity loss (if details adhere the cylinder non-tightly). Moreover, broken rings are necessarily to be replaced. In addition, installation of new components can be presupposed at performing works on repair or tuning of the engine.

Premature details wear-out often becomes the result of low-quality fuel or oil use, as well as intensive engine exploitation. Moreover, the rings lose their elasticity because of heavy carbon deposit inside of piston head grooves. This happens, for example, if the car was not used for long which led to motor oil thickening.

The following signs point at elements breakdown: engine power decrease, increase of fuel or motor oil consumption, unusual colour of exhaust gases. Moreover, there is deposit or greasing material found on spark plugs threads during their inspection which is performed at every oil replacement. It also can be a sign of piston rings defect.

If you don’t have appropriate skills, then components installation should be entrusted to service station specialists. The case is that rings are replaced together with pistons. Moreover, boring and honing operations of cylinders are performed. Using the piston rings kit it is important to correctly define the type of each of them and take into account location in relation to each other. Incorrect installation of rings can lead to their damage.

How to select piston rings

These details are divided into compressional and oil control. Rings of the first type prevent break out of gases from the combustion chamber into the engine crankcase. And oil control piston rings are necessary for removing excesses of oil from cylinder walls.

The oil control ring unlike with the compressional one has U-shaped cross section and an expansion spring. While the compression rings differ by their thickness which helps to correctly define their installation order.

Cast iron or steel are used as a production material. Moreover, the parts can be covered with chrome or molybdenum. Molybdenum coating is usually used producing the upper compression ring undergoing the heaviest loads.

Components service life mostly depends on the manufacturing company. For example, qualitative and durable piston rings are presented in the assortment of MAHLE Original and Japanparts brands.

Buying details you should take into account the type, volume and power of the engine. Also, you should keep in mind the cylinder diameter and sizes of rings themselves.

When buying a piston rings kit pay attention that it can include details for all the pistons or only for one. In order to install components correctly consider markings, if it is present. Many manufacturers mark rings with numbers which point their installation order.