See if the logo is complete. The packaging quality of authentic products is good, the handwriting on the packaging box is clear, and the overprint color is bright. Packaging boxes and bags should be marked with product names, specifications, models, quantities, registered trademarks, factory names, factory addresses and telephone numbers, etc. Some manufacturers also make their own markings on accessories. Some important components, such as generators, distributors, fuel injection pumps, are also equipped with instructions, certificates and inspector's stamps to guide users to use and maintain correctly. Careful recognition should be made when selecting stamping parts for automobiles in order to prevent the purchase of counterfeit and inferior products.

See if the geometric dimensions are deformed. Some parts are easily deformed due to improper manufacture, transportation and storage. When inspecting, the axle parts can be rolled around the glass plate to see if there is light leakage between the parts and the glass plate to judge whether they are bent or not; when choosing the clutch driven disc steel sheet or friction sheet, the steel sheet and friction sheet can be raised in front of the eyes to observe whether they are warping; when choosing the oil seal, the oil seal end surface with the skeleton should be round, which can be bonded with the flat glass without bending; and the outer edge of the skeleton oil seal should be corresponding to the non-skeleton oil seal. Straighten up, deform it with hand grip, and restore it to its original state after loosening hands. When choosing and purchasing all kinds of liners, attention should also be paid to checking the geometric size and shape.

See if the joint is smooth. In the process of handling and storage, parts often produce burrs, indentations, damages or cracks in the joint due to vibration and knocking, which affect the use of parts. When choosing and purchasing, attention should be paid to inspection. See if there is rust on the surface of automobile parts. The surface of qualified spare parts has both a certain accuracy and bright brightness. The more important the spare parts are, the higher the accuracy, the stricter the anti-rust and anti-corrosion of packaging. When choosing and purchasing, attention should be paid to inspection. If rust spots, mildew spots or cracks of rubber parts, loss of elasticity, or obvious turning tool lines on the journal surface are found, they should be replaced.

See if the protective surface is in good condition. Most parts are coated with protective coating when they leave the factory. For example, the piston pins and bearing bushes are protected by paraffin; the surface of piston rings and cylinder liners are coated with anti-rust oil and wrapped with wrapping paper; and the valves and pistons are sealed with plastic bags after being immersed in anti-rust oil. If the seal sleeve is damaged, packing paper is lost, rust-proof oil or paraffin is lost, it should be replaced.

See if the glued parts are loose. Parts consisting of two or more parts are assembled by pressing, gluing or welding, and loosening is not allowed between them, such as oil pump plunger and adjusting arm are assembled by pressing; clutch driven wheel and steel sheet are riveted together, friction sheet and steel sheet are riveted or glued; paper filter core framework and filter paper are glued together; electrical equipment; The threads are welded. If looseness is found in the purchase, it should be replaced.

See if the rotating parts are flexible. When choosing the assembly of rotating parts such as oil pump, the pump shaft should be rotated by hand, so as to be flexible and without sticking; when choosing rolling bearing, one hand supports the inner ring of the bearing, the other hand rotates the outer ring, and the outer ring should rotate freely and quickly, and then stop gradually. If the rotating parts do not rotate properly, it means that the interior is rusted or deformed. Don't buy it. See if the assembly parts are missing. Normal assembly parts must be complete and intact in order to ensure smooth assembly and normal operation. If the individual small parts on some assembly parts are missing, the assembly parts will not work or even be scrapped.