There are two types of piston rings for engine overhaul: standard size and enlarged size. We have to choose the piston ring according to the previous cylinder processing size. If a piston ring of the wrong size is selected, it may not fit, or the gap between the parts is very large. But nowadays most of them are of standard size, few of them are enlarged.

Inspection of the elasticity of the piston ring: The elasticity of the piston ring is one of the important conditions to ensure the tightness of the cylinder. If the elasticity is too large or too small, it is not good. It must meet the technical requirements. The piston ring elasticity tester is generally used for detection. In practice, we generally use a hand to judge roughly, as long as it is not too loose, it can be used.

Inspection of light leakage of piston ring and cylinder wall: In order to ensure the sealing effect of the piston ring, the outer surface of the piston ring is required to be in contact with the cylinder wall everywhere. If the light leakage is too large, the local contact area of the piston ring is small, which may easily lead to excessive blow-by gas and excessive oil consumption. There is special equipment to detect the light leakage of the piston ring. The general requirements are: no light leakage is allowed within 30 ° of the open end of the piston ring, and no more than two light leakages are allowed on the same piston ring. The corresponding center angle must not exceed 25 °, the total center angle corresponding to the light leakage arc length on the same piston ring must not exceed 45 °, and the gap at the light leakage must not exceed 0.03mm. If the above requirements are not met, you need to re-select the piston ring or repair the cylinder.

It is important to note that before the piston ring is installed, it is necessary to determine whether the cylinder liner is also chrome-plated.If the surface of piston ring and cylinder liner have been chrome-plated, it is easy to produce the phenomenon of Cylinder score.