Key points of piston assembly when overhauling the engine

Engine overhaul is a common repair project in repair shops. It is to replace engine components such as pistons, piston rings, valve seals, and bearing bushings to eliminate engine oil burning and insufficient power failures, and restore the normal working performance of the engine.
During the engine overhaul operation, the assembly quality of each component directly affects the engine performance after maintenance, and the assembly of the piston group is the top priority. If the assembly is improper, it may cause serious consequences such as damage to the components. The following will explain the key points of the piston set assembly.

Assembly operation: Apply oil to the piston pin, piston pin seat hole, and connecting rod small head bushing, put the connecting rod small head into the piston and align the pin hole with the piston pin, pass the piston pin through and install it in place, and install limit springs at both ends of the piston pin seat hole.
Key points of assembly: There are direction marks on the connecting rod and piston, usually protruding or arrows. These marks should usually be in the direction of the timing system, that is, the marks on the connecting rod and the top of the piston should be kept on the same side. Be careful not to install them incorrectly during assembly.

Assembly operation: There are generally 3 piston rings, from top to bottom, there are 2 gas rings and 1 oil ring. Each ring has a direction mark, such as the letter "TOP", with the side with the direction mark facing towards the top of the piston.

Assembly points: The wrong position of the piston ring is a key factor in determining the sealing effect of the piston ring. The opening of the first air ring should face the cylinder wall with less pressure on the side, which can slow down wear. If it is an integral oil ring, the openings of the three piston rings should be staggered by 120º; if the oil ring is composed of two oil scrapers, the two gas rings are staggered by 180º, the two oil scrapers of the combined oil ring are staggered by 180º, and the second gas ring and the upper oil scraper of the combined oil ring are staggered by 90º.